Avoidance: From threat encounter to action execution

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Arnaudova, I.

Publication date

2015

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Arnaudova, I. (2015). Avoidance: From threat encounter to action execution. Boxpress.

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Inna Arnaudova

Avoidance:

From threat encounter

to action execution

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Avoidance:

From threat encounter

to action execution

Inna Arnaudova

Department of Clinical Psychology

Faculty of Social and Behavioral Sciences

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• Inna Arnaudova

ISBN: 978-94-6295-388-8 Cover illustration: Toni Ortega

Cover design: Toni Ortega & Inna Arnaudova Lay-out by: Inna Arnaudova

Printed by: Proefschriftmaken.nl/Uitgeverij BOXPress Published by: Uitgeverij BOXPress, ’s-Hertogenbosch

This work was supported by an Innovation Scheme (Vidi) Grant (452-09-001), awarded to Tom Beckers by the Netherlands Organization for Scientific Research (NWO).

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Avoidance:

From threat encounter

to action execution

ACADEMISCH PROEFSCHRIFT ter verkrijging van de graad van doctor

aan de Universiteit van Amsterdam op gezag van de Rector Magnificus

prof. dr. D.C. van den Boom

ten overstaan van een door het College voor Promoties ingestelde commissie, in het openbaar te verdedigen in de Agnietenkapel

op dinsdag 8 december 2015, te 14:00 uur

door

Inna Borislavova Arnaudova geboren te Varna, Bulgarije

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Promotors: Prof. Dr. T. Beckers Universiteit van Amsterdam KU Leuven

Prof. Dr. M. Kindt Universiteit van Amsterdam

Overige leden: Prof. Dr. A. Moors KU Leuven

Prof. Dr. A. Fischer Universiteit van Amsterdam

Prof. Dr. A. Arntz Universiteit van Amsterdam

Prof. Dr. M. Craske University of California -Los Angeles

Dr. S. de Wit Universiteit van Amsterdam

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Chapter 1 Introduction

On an average day people might face a variety of threats to their survival or well-being: a raccoon with rabies in the forest, a car running a red light, or a yelling commuter on the train. Navigating the scene might seem challenging, but most individuals manage it without too much concern about their safety. They keep their distance from dangerous objects or people, engage in multiple other avoidance strategies and ultimately survive the day unharmed without consid-erably limiting their activities. For individuals suffering from clinically severe anxiety, however, this avoidant mode of responding becomes all-absorbing. It severely impairs their functioning (American Psychiatric Association, 2013) by preventing them from participating in activities that most people would deem non-threatening. An individual with dog phobia, for example, might avoid not only petting dogs, but also entering parks where others might walk their dogs or watching movies such as K-9 (Daniel, 1989) or 101 Dalmatians (Herek, 1996). In-depth understanding of both adaptive and maladaptive avoidance can ultimately lead to the development of more successful prevention and treatment strategies for clinically severe anxiety and pathological avoidance. This doctoral disserta-tion presents a novel theoretical framework for adaptive avoidance of threat and its proliferation in anxiety pathology. The dissertation then reports empirical investigations of key ideas of the framework.

In this introduction, we first briefly review the theoretical model presented in more detail in Chapter 2. Then, we introduce the laboratory paradigm used for testing the ideas of the model in the experiments reported in the subsequent chapters (Chapters 3 to 6). Lastly, we give the outline of the dissertation and the empirical investigations reported in it.

1.1 Threat avoidance response selection and

execution

While the acquisition of avoidance was a hot topic for research by learning ex-perts up to the 1970s (Krypotos, Effting, Kindt, & Beckers, 2015), inspiring more than one influential theory (e.g., two-factor theory, Mowrer, 1939; and

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species-specific defense reactions theory, Bolles, 1970), the selection and execution of avoidance responses in the presence of threat have been studied far less, par-ticularly in humans. Response selection refers to the process through which a particular avoidance response is chosen from the available behavioral alternatives (e.g., withdrawal or endurance), eventually leading to action. In Chapter 2, we present a novel theoretical framework for human threat avoidance response selection and execution (TeARS model).

In the TeARS model, we define avoidance as “any covert or overt action that

functions to physically (spatially or temporally) or psychologically distance the agent from perceived or actual threat,” so that the framework can incorporate the

large variety of avoidance behaviors performed by humans, especially those with anxiety pathology: from running away from a house on fire to planning a doctor’s appointment on the day of prom, so as to avoid being laughed at because of lack of a date for the prom.

Following a long tradition of dual-process models (Strack & Deutsch, 2004), we propose that avoidance actions result from the interaction of fast, automatic, reflex-like avoidance tendencies and a slow and controlled reflective evaluation of behavioral alternatives. Automatic avoidance tendencies refer to the preference of an individual to react to a threat encounter with avoidance rather than with another response (e.g., approach). These tendencies might or might not result in observable behavioral output (avoidance action). Thus, the final behavioral output is assumed to be resulting from the interaction of both a reflexive and a

reflective behavioral system.

Avoidance tendencies are assumed to be present whenever a threat is encoun-tered, even when the individual is not consciously aware of a threat’s presence. Threat stimuli that are unavailable to consciousness have been shown to pro-duce a number of defensive responses (e.g., sweating; ¨Ohman & Soares, 1993) and we maintain, like others ( ¨Ohman, 2013), that avoidance tendencies are sim-ilarly primed. We view avoidance tendencies as an integral part of the defensive motivational network, which is assumed to be activated in response to threat signals and guide all defensive responses (e.g., Lang, 1995). We further propose that individual differences modulate the strength of these automatic avoidance tendencies.

According to the TeARS model, the appraisal of threat imminence serves as a gatekeeper for the optimization of the response selection process. Threat immi-nence refers to the physical (spatial and temporal) and psychological (e.g., direc-tion of the threat movement) distance of the threat from the organism (Fanselow & Lester, 1988). The role of threat imminence in response selection has been extensively studied in non-human animals (rats; Fanselow & Lester, 1988). How-ever, even though the threat imminence account has often been incorporated in theoretical formulations on human fear and defensively motivated behavior (e.g., Craske, 1999, 2003; Lang, Bradley, & Cuthbert, 1997), until recently, it lacked empirical validation. Mobbs et al. (2009, 2007) were the first to show that the same neural mechanisms that operate when processing threat at different immi-nence levels in rats are active in humans. Thus, threat immiimmi-nence has a central role in the TeARS model. We propose that when threat imminence is high, re-sponse selection is optimized by deactivating the slow and cumbersome reflective system, resulting in a reflexive withdrawal or flight. However, when threat

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im-minence is lower, an evaluation of various behavioral alternatives takes place. Under such conditions, the final behavioral decision of which action to undertake is assumed to be postponed until multiple factors (e.g., behavioral repertoire and affordances) are considered, provided that no changes in threat imminence occur. Consequently, changes in threat imminence need to be attended to and threat imminence appraisal has to be constantly updated in order to choose the most appropriate action.

Once an avoidance response is performed, situational feedback either termi-nates the process or restarts it. According to TeARS, if a competing activation of the appetitive motivational network is present (e.g., craving for food), the conflict would be resolved in an avoidant way, since the defensive motivational network would take control precedence (e.g., Frijda, 1996) and the output of the appetitive motivational network would be obstructed.

The TeARS model also covers situations of imbalance, where one of these sys-tems (reflexive or reflective) dominates over the other and unduly guides behavior, as in pathological anxiety. It proposes five pathways to how adaptive avoidance can go awry. First, anxious individuals are proposed to have excessively potent avoidance tendencies. Second, conditions of extreme anxiety are suggested to be associated with overestimation of current threat imminence. Third, the reflective system of individuals suffering from anxiety pathology is proposed to be incapable of modulating responding. Fourth, according to the TeARS model, regulatory re-sources might as a whole be depleted in these individuals as a result of over-usage of the reflective system. Last, but not least, avoidance is assumed to become habitual with repetitive performance.

The TeARS model integrates isolated findings from a wide range of disci-plines: human and non-human animal laboratory research, emotion theory, social psychology, human ethology and clinical psychology. Importantly, it presents a comprehensive view on avoidance and its transition from adaptive to maladaptive avoidance in clinically severe anxiety.

Lastly, the model allows making novel testable predictions about human be-havior under conditions of threat and suggests avenues for future research. This doctoral dissertation contains empirical investigations of some of these ideas. All studies presented here use a similar laboratory paradigm for testing the tenets of TeARS: classical conditioning. We continue with describing the classical con-ditioning paradigm used in these experiments and explaining the advantages of using this paradigm.

1.2 Classical conditioning

Classical or Pavlovian conditioning (after the pioneer in the field, Pavlov, 1927), is among the most widely used paradigms in the study of fear/threat learning (Beckers, Krypotos, Boddez, Effting, & Kindt, 2013) and reward learning. In its aversive form, a naturally aversive stimulus such as an electric stimulation (shock) is used as an unconditioned stimulus (US) to provoke a defensive unconditioned response (e.g., fear-potentiated eye blink startle; UR) across individuals (Figure 1.1A). In its appetitive form, a naturally appetitive stimulus, such as chocolate, is used to produce an appetitive UR (e.g., salivation). Next, a neutral stimulus (e.g., a geometric shape; conditioned stimulus, CS+) is paired with this US until

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an association between the two stimuli is learned (Figure 1.1B). Later, upon the presentation of the unaccompanied CS+, a conditioned response (e.g., sweating or salivation; CR) is observed (Figure 1.1C). Some theories propose that the elicitation of CR is due to the CS evoking an expectation of the US (Lovibond, 2006; Lovibond & Shanks, 2002; Reiss, 1991).

In the lab, a differential cue-conditioning paradigm is mostly used, in which responding to the CS+ is compared to responding to a neutral stimulus never paired with the US (CS-). Thus, in aversive differential classical conditioning, the CS- acts as a safety stimulus, signaling the absence of the aversive US. Our choice to use a differential cue-conditioning paradigm in the empirical studies reported in this dissertation is motivated by several factors.

Figure 1.1: An aversive classical conditioning procedure with a neutral geometric

shape as CS and an electric stimulation as US

DANGER! DANGER!

A

B

C

US

UR

CR

CS+

First, this paradigm allows for the simultaneous measurement of multiple con-ditioned responses to the CS+. Regardless of whether an aversive or an appetitive conditioning procedure is used, CRs can be divided into three distinct categories: verbal, physiological and behavioral (Figure 1.2, Lang, 1995; Lang & Davis, 2006). During aversive conditioning (Figure 1.2A), individuals can verbally report their current distress or threat expectancy (see Figure 1.2B for responses in appetitive conditioning). Physiological activation can be examined through the measure-ment of eye-blink startle potentiation or skin conductance responses (SCR) to

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aversively conditioned CSs. Most importantly, both, automatic action tendencies (e.g., Krypotos, Effting, Arnaudova, Kindt, & Beckers, 2014) and overt behav-ior (e.g., Lommen, Engelhard, & van den Hout, 2010) can be measured. Thus, the aversive classical conditioning paradigm allows to test the ideas proposed by TeARS about avoidance tendencies and actions and to examine whether these ideas are also valid for other well-established defensive reactions.

Figure 1.2: Categories of conditioned responses following aversive (A) and

ap-petitive (B) conditioning

Aversive'Responses'

Appe,,ve'Responses'

Approach tendencies, Overt approach Avoidance tendencies Overt avoidance Craving, Reward Expectancy Distress, Threat Expectancy Startle, Skin conductance Salivation

Behavioral

_Behavioral

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Second, the classical conditioning paradigm allows for testing conditioned re-sponses in a highly controlled environment. Variables such as the perceptual and temporal characteristics of both the CSs and the US can be controlled. Also, by using initially neutral stimuli as CSs and holding constant the number of CS pre-sentations being reinforced with a US, we can maintain the same level of threat imminence across individuals. In a differential cue-conditioning paradigm, where the CS+ is always reinforced and the CS- is never reinforced, the difference be-tween the two CSs is apparent and very similar responses are observed across individuals (Beckers et al., 2013; Lissek, Pine, & Grillon, 2006). This control of the threat imminence level across individuals is important for the examination of many ideas proposed in TeARS. For example, we can test the effects of threat imminence changes (e.g., approaching versus withdrawing threats), without con-sidering confounding variables such as discrepant personal experiences with the CSs among individuals or perceptual differences between the CSs.

In the TeARS model, we also propose that individual differences might play an important role in modulating avoidant responding. In order to examine such modulation by trait characteristics, weaker or more ambiguous situations are re-quired than the standard aversive differential cue-conditioning paradigm (Beckers et al., 2013; Lissek et al., 2006). Fortunately, other variants of the classical con-ditioning paradigm offer the opportunity for testing responding to such more or less ambiguous threat situations. For example, in blocking procedures, a novel

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stimulus (CSB) is paired with an already established CS (CSA, previously

fol-lowed by an aversive US). The compound CSACSB stimulus is then followed by

the same outcome (US) that followed CSA when presented alone. As a result

CSB becomes ambiguous, because the to-be-expected outcome for CSB remains

unclear. Individual differences in threat expectancies have been readily observed in such paradigms (Boddez et al., 2012). Another ambiguous paradigm is the generalization paradigm (Lissek et al., 2008; Lommen et al., 2010), where follow-ing the aversive differential cue-conditionfollow-ing of two stimuli at the opposite ends of a continuum (e.g., a small circle as CS- and a large circle as CS+, Lissek et al., 2008), a number of intermediate stimuli (e.g., circles of different sizes) are presented. Those generalization stimuli (GSs) also elicit a degree of defensive responding, with the strength of responding depending on the perceptual simi-larity between a given intermediate stimulus and the CS+. Responding reduces incrementally as perceptual similarity to the CS+ reduces (Lissek et al., 2008). Individual differences in conditioned fear responding have been observed in such perceptual generalization paradigms (e.g., Lissek et al., 2010) and it has been shown that avoidance behaviors generalize to the ambiguous intermediate stimuli as well, with some modulation based on individual characteristics (van Meurs, Wiggert, Wicker, & Lissek, 2014). Thus, the third reason for using variants of the classical conditioning paradigm for testing the ideas of the TeARS model is that we can examine whether personality dispositions affect avoidance responding as proposed by TeARS.

Finally, aversive classical conditioning allows for testing responses to threats that are subliminally rather than consciously processed. Subliminal or pre-attent-ive processing occurs when the brief presentation (between 14 ms and 33 ms) of a CS is immediately followed by the presentation of a novel neutral stimulus ( Öhman & Soares, 1993) and the individual remains unaware of the CS presentation. As a result of pre-attentive processing of the CS, a myriad of defensive responses can be elicited in the individual (e.g. SCR, Esteves, Dimberg, & Öhman, 1994) and it has been proposed that such subliminal processing can also result in avoidance tendencies ( Öhman, 2013). The TeARS model similarly maintains that conscious awareness of threat might not be necessary for the activation of reflex-like avoid-ance tendencies.

In conclusion, the classical conditioning paradigm is a useful tool for the exam-ination of both defensive and appetitive responding and its aversive variants are particularly suited for critically testing hypotheses that follow from the TeARS model.

1.3 Outline of the doctoral dissertation

This doctoral dissertation firstly presents the novel iterative model for threat avoidance response selection and execution, referred to as the TeARS model, in

Chapter 2. Subsequent chapters are devoted to testing some of the model’s key

ideas.

In Chapter 3, we examine whether pre-attentive processing of conditioned threat results in the activation of conditioned avoidance tendencies and whether supraliminal changes in threat imminence can, in turn, tune attentional process-ing. We evaluate the results in light of the adaptive advantage of attentionally

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and pre-attentively prioritizing threat processing.

In Chapter 4, we evaluate individual differences in fear generalization across response systems to clarify which fear responses, if any, are affected by a known vulnerability factor for anxiety, neuroticism (e.g., D. Watson, Gamez, & Simms, 2005).

In Chapter 5, we examine other individual factors pertinent to the experience of anxiety and how they relate to discriminatory fear learning and avoidance in ambiguous situations.

In Chapter 6, we investigate a different kind of threat than one that is classi-cally conditioned. Some theories propose that negative mood can serve as an in-ternal negative cue and directly influence behavior (e.g., Baker, Piper, McCarthy, Majeskie, & Fiore, 2004). If negative mood can serve as an internal threat, it should reduce appetitive behavior according to the TeARS model. In two ex-periments, we examine the effects of negative mood on appetitive learning and examine whether negative mood impairs the formation of positive associations and the acquisition of possibly adaptive behaviors for coping with negative mood. In Chapter 7, we re-examine the TeARS model in light of the findings from the empirical studies, discuss the implications of the research and theory presented in this doctoral dissertation and give suggestions for future research. We also examine treatment protocols for clinically severe anxiety from the perspective of the TeARS model and suggest potential improvements to clinical interventions.

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Chapter 2 Threat avoidance response

selection and execution (TeARS):

A comprehensive model of

avoidance

A version of this chapter is in preparation as:

Arnaudova, I., Craske, M., Fanselow, M., Kindt, M., & Beckers, T. (2015).

Threat avoidance response selection and execution (TeARS): A comprehensive model of avoidance.

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Abstract

Dysfunctional avoidance lies at the core of anxiety pathology. Here, we pro-pose a model for threat avoidance response selection and execution (the TeARS model), which describes the processes involved in avoidance from threat encounter to final behavioral output. In our model, which incorporates empirical research and theories from animal, social, clinical and experimental psychology research, avoidance is an umbrella term encompassing a large variety of defense behaviors observed in human threat responding. Our framework centers on the importance of threat imminence appraisal and automatic avoidance tendencies and the no-tion of two behavioral control systems, one that is reflective and another that is reflexive. Further, we propose five pathways through which adaptive avoidance can become dysfunctional in clinically severe anxiety.

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“Never confuse movement with action“

Ernest Hemingway (quoted in Hotchner, 1966) Since Confucius (475 BC) and Aristotle (350 BC), philosophers and scientists have been fascinated by the behaviors of individuals, the motivational forces be-hind them, their purpose and (ir)rationality. However, action or lack thereof in emotional situations remains poorly understood despite being one of the primary contributors to functional impairment in individuals suffering from a number of psychiatric disorders. In particular, behavioral avoidance can lead to substan-tial limitations in daily life for people with clinically severe anxiety (Rachman, Craske, Tallman, & Solyom, 1986). The link between threat and avoidance behav-ior has been addressed in a number of theories (e.g., Bolles, 1970; Lovibond, 2006; Mowrer, 1939), but empirical assessment of the relationship is limited (Grillon, Baas, Cornwell, & Johnson, 2006). A recent spur of research on the topic has highlighted the need to enhance dialogue among researchers from various disci-plines, who often define avoidance in fundamentally different ways (Eder, Elliot, & Harmon-Jones, 2013; Lovibond, 2006). A common conceptual framework for understanding avoidance in the context of threat is needed. The purpose of this review is to evaluate existing theoretical assumptions and empirical data on the relationship between threat and avoidance and to propose an evidence-based inte-grative model for threat-avoidance responding. Our Threat Avoidance Response Selection and Execution (TeARS) model addresses the selection and execution of avoidance responses based on threat imminence appraisal. We also consider the ways in which avoidance response selection and execution is dysregulated in the context of clinically severe anxiety. We believe that the TeARS model will gener-ate ideas for basic and applied research into the mechanisms underlying avoidance responding and will eventually help to improve interventions for emotional disor-ders.

Our paper begins with an operationalization of avoidance responding based on human and non-human animal research and theorizing to date. Next, we examine animal models of behavior, which elucidate the guiding forces behind response selection in the context of threat. We review evidence for a threat imminence model of response selection and the findings from human studies that support a role of threat imminence in human avoidance response selection. We then turn to empirical data from human laboratory studies regarding automatic action tenden-cies, including avoidance tendentenden-cies, as well as overt avoidance behavior, spanning from withdrawal and flight to threat endurance with or without the aid of safety behaviors. We introduce dual process models of behavior, where action control is governed by the interaction between two systems, a reflexive (automatic) and a reflective (controlled) one. Within the TeARS model, we incorporate elements of threat imminence appraisal, automatic action tendencies (as part of a reflexive mode of responding) and reflective control of overt behavior under conditions of less imminent threat. Finally, we examine the effects of clinically severe anxiety on avoidance response selection and execution and suggest five pathways through which avoidance might become pathological. Throughout the paper, we provide indications about further research and highlight the gaps in our current

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under-standing of avoidance.

2.1 Definition of avoidance

The wide-ranging usage of the term avoidance among social psychologists, clin-icians, learning theorists and laymen impedes scientific progress and conceptual advancement. Therefore, before embarking upon a detailed analysis of threat avoidance response selection and execution, a clear definition of avoidance is war-ranted (Lang & Bradley, 2013; Lovibond, 2006). In this section, we evaluate common elements of definitions of avoidance from different theoretical perspec-tives. We then derive a new definition of avoidance behavior in response to threat that applies to healthy as well as anxious individuals.

Dictionary definitions state that to avoid is “to prevent something bad from

happening” and that to avoid is “to stay away from someone or something, or not use something” (“Avoid”, 2014). In psychology, the notion of avoidance plays a

central role in theories of fear learning. There, avoidance is defined as a response that serves to prevent an unpleasant event (i.e., an unconditioned aversive stimu-lus, US, such as an electric shock) from occurring in the future (Lovibond, 2006). The overlap with the first meaning of the dictionary definition is clear. Early theorists proposed that the avoidance response was reinforced by termination of a warning signal (i.e., conditioned stimulus, CS, such as a neutral tone) that preceded the aversive event in an aversive Pavlovian conditioning situation (e.g., Mowrer, 1939). The term escape referred to any response that resulted in the ter-mination of the US following its onset (Lovibond, 2006; Mowrer, 1939). However, subsequent research by Bolles (1970) showed that termination contingencies play a minimal role in motivating any defensive behavior in animals, including avoidance, thus undermining the idea that instrumental learning (acquiring the knowledge that a specific action has a particular outcome) is crucial for the acquisition of avoidance responding.

Instead, Bolles (1970) suggested that animals have a range of pre-wired species-specific defense responses, including freezing, fleeing, and fighting1_{, which are} activated in the presence of threat, because they have a phylogenetic association with survival. These behaviors were judged to have persevered from generation to generation due to their functionality, but the specific behaviors selected for expression were influenced by the characteristics (or affordances) and demands of a given situation (Bolles & Fanselow, 1980). In subsequent elaborations, physical or psychological distance from threat (termed predatory/threat imminence) was regarded as the most important guiding factor for the selection of the appropriate form of defensive behavior, with the affordances of a given situation or termination of an aversive stimulus playing a minimal role in response selection (Fanselow & Lester, 1988)(see section 2.2.1). This reconceptualization brought the use of the term avoidance in the psychological literature closer to the second dictionary meaning of the term to avoid.

Clinical or diagnostic definitions of avoidance, such as the one provided in

1_{New responses could be learned through instrumental contingencies, sometimes with}

diffi-culty, if the pre-wired behaviors do not fulfill their function (Bolles, 1970). Opposite responses (e.g., moving away when moving towards is the natural response) seem, however, almost impos-sible to acquire (Hershberger, 1986).

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the Diagnostic and Statistical Manual of Mental Disorders - 5thedition (DSM-5;

American Psychiatric Association, 2013), similarly emphasize the distance from threat signals: “the act of keeping away from stress-related circumstances: a

ten-dency to circumvent cues, activities and situations that remind the individual of a stressful event experienced.” It is important to note that in contrast to

ear-lier conceptualizations in psychology, this definition of avoidance has no response contingency component. The diagnostic criterion of avoidance for most anxiety disorders further clarifies that if a threatening or stressful stimulus is not actively avoided, it is endured with significant distress (American Psychiatric Associa-tion, 2013). Endurance of threat is usually accompanied by an array of actions that serve the function of safety seeking (Thwaites & Freeston, 2005), such as remaining in proximity to a trusted companion, superstitious objects, or certain medications. These behaviors are often coined safety behaviors, because they increase the subjective perception of safety.

Social psychology researchers utilize a much broader concept of avoidance

mo-tivation, which can be elicited by any negative stimulus rather than threat stimuli

in particular (e.g., Chen & Bargh, 1999). Nonetheless, distance from the nega-tive stimulus is again viewed as underlying automatic avoidance tendencies, as described in more detail below (Krieglmeyer, De Houwer, & Deutsch, 2013). Sim-ilarly, emotion theorists have suggested that behaviors are primarily modes of distance regulation (Frijda, Kuipers, & ter Schure, 1989) and that any behavior that increases the distance from a negative stimulus can be seen as avoidance.

What these definitions and conceptualizations all share is the idea that avoid-ance increases the distavoid-ance of the agent from negative stimuli more broadly or threatening stimuli more specifically. Given our goal of developing a model that explains avoidance response selection and execution in the presence of threat, we propose the following definition of avoidance: “any covert or overt action that

functions to physically (spatially or temporally) or psychologically distance the agent from perceived or actual threat.” We focus on avoidance as having a

spe-cific function of distancing from threat, which may include actions that increase psychological distance without affecting physical distance. The concept of

psy-chological distance in animal models of response selection pertains to two main

variables: the type of predator (e.g., big or small) and the direction of its move-ments (e.g., towards or away; Fanselow, 1997). We later elaborate on the factors appraised during threat imminence estimations in humans (see section 2.6). An example of a human action that serves to increase psychological distance without changing the physical properties of threat is the ascertainment of the presence of a friend when one is under the threat of having to walk the street at night, for example. In the same scenario, an avoidance response that changes the physical distance from threat is to stay off the streets at night altogether. Thus, our def-inition encompasses safety behaviors, which function to psychologically distance oneself from threat and increase feelings of safety, as well as withdrawal and flight behaviors, which function to increase physical distance and might result in the cancelation of threat.

In contrast to the early models of avoidance learning proposed by Mowrer (1939) and Miller (1941), our definition does not make reference to reinforcement of the current avoidance response. Feedback about whether the current avoidance action has fulfilled its function does not occur before the response is executed,

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and thus cannot affect its selection. We do not differentiate between avoidance and escape at the point of response selection. A cognitive representation of the anticipated consequences of a particular behavioral response (Lovibond, 2006), however, might play a role in the decision making process for avoidance response selection (as described in more detail in section 2.6). The perceived consequence in some circumstances may be based on the success of prior responses undertaken under similar circumstances (Bouton, Winterbauer, & Todd, 2012). Overall, the instrumentality of the behavior is not of primary concern within our definition, because not all avoidance behaviors are instrumentally motivated (for further clarification and examples of actions for which instrumental learning might (not) play a role, see later sections).

Finally, we maintain that the specific form of the avoidance behavior can be shaped by the specific threat. Thus, using our definition, avoidance can occur in response to a CS (as a warning signal of future threat) or a US (as a present threat). The concept of threat in our model is operationalized as any object, person or event (internal or external) that might endanger one’s physical health (e.g., a weapon that can inflict wounds) or psychological well-being (e.g., an event that can lead to financial losses and disappointment). We acknowledge that other behaviors, such as fighting or bonding with other individuals (S. E. Taylor, 2006), can also play a role in dealing with threat (Fanselow & Lester, 1988), but possibly under very specific circumstances. Here, we focus on the phenomenon of threat

avoidance, because of its clinical significance; we address in subsequent sections

how the occurrence of other behaviors can be explained through the TeARS model as well.

2.2 Response selection to threat

In this section, we address the issue of response selection in animals and hu-mans, and use findings from research on response selection as a foundation for the TeARS model. The learning of avoidance responses has been the focus of multi-ple associative and instrumental process theories (e.g., Lovibond, 2006; Mowrer, 1939). Avoidance learning research focuses on specific factors that influence the expression of a particular response towards a particular stimulus. An in-depth discussion of avoidance learning is beyond the scope of this review (see Bolles, 1972 and Krypotos, Effting, et al., 2015). Instead, we address the processes that take place from the moment of stimulus encounter to avoidance expression and the determination of the form of the avoidance response.

2.2.1 Evidence from animal research

Defensive responding and avoidance has been examined in-depth in a number of species (e.g., horses, Keiper & Berger, 1982; birds, Schaller & Emlen, 1962; dogs, Solomon & Wynne, 1953). Research in rats, in particular, has resulted in well-specified threat response-selection theories (Fanselow & Lester, 1988). Thus, we turn first to results from animal studies for clues about important factors in threat avoidance selection.

An immediate action is mandated in the presence of threat in order to preserve chances for survival (Bolles & Fanselow, 1980; Fanselow, 1997; Ozono, Watabe, &

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Yoshikawa, 2012). Initially, laboratory animal research studied avoidance in rela-tion to threat intensity and reinforcement schedules (Miller, 1941; Mowrer, 1939). However, theoretical propositions about the role of reinforcement contingencies of defensive behavior (avoidance, escape and fear reduction) did not account fully for the variance observed in natural animal behavior. This led Bolles (1970) to propose his influential species-specific defense response (SSDR) theory. Ac-cording to the SSDR framework, an animal’s behavioral repertoire following a threat encounter is limited due to the activation of a defensive motivational

net-work. The available defense reactions include fleeing, freezing and fighting even

before any behavioral learning has taken place. Other, incompatible behaviors are suppressed due to the dominance of the defensive motivational network. For example, pain-motivated recuperative behaviors (such as resting and healing) are inhibited through analgesia, because these behaviors are incompatible with defen-sive responses (Bolles & Fanselow, 1980). The SSDR model further posits that defensive behavior in reaction to a threat encounter is primarily guided by extrin-sic feedback from the environment regarding whether the situation has changed as a result of response execution, rather than by the actual termination of threat (Bolles, 1970). The SSDR theory thus represented a major shift from earlier mod-els of avoidance as an action that prevents the occurrence of a negative event to avoidance as the execution of any of a range of evolutionary pre-wired behaviors. In an expansion of the SSDR framework, Bolles and Fanselow (1980) included the behavior of animals following their return to safety. When preservation has been achieved but defense has not been optimal and the animal has been injured, the animal enters a recuperative stage where injury is of primary concern. Once recuperation is complete, the animal returns to its preferred activity pattern until another (potential) threat is detected.

The combination of the perception-defense-recuperation loop (PDR; Bolles & Fanselow, 1980), the SSDR framework, and laboratory animal research with varied threat intensities and reinforcement schedules, led to the conclusion that

predatory imminence is the primary determinant for threat response selection

(Fanselow, 1997; Fanselow & Lester, 1988). Predatory imminence is determined by the temporal and geographic position of the predator relative to the prey and by the prey’s perception of the predator’s psychological distance, based on the type of predator and the direction of its movements. Behavior is thus oriented towards mitigating threat imminence by maintaining distance from the predator and allowing the animal to return to its preferred pattern of activity in the absence of predatory potential (Fanselow & Lester, 1988).

In the predatory imminence model, activation of the defensive motivational network at different levels of the threat imminence continuum constrains the be-havioral repertoire of the animal and determines the form of the behavior being executed (see Figure 2.1). As long as no threat has been encountered, the animal organizes its behavior so that the risk of encountering a predator is controlled. For example, animals will reduce the number of meals, while increasing meal size, in order to maintain a balanced energy intake, when food procurement is associated with an increased probability of predatory encounter (Fanselow, Lester, & Helm-stetter, 1988). Behavior changes dramatically once threat has been detected. For the rat, the predominant behavior at this stage is full-body freezing. Later, upon close contact with the threat, circa-strike behaviors characterized by an activity

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burst and loud vocalizations occur. Once the animal has returned to safety, if injury has been sustained the animal engages in recuperative behaviors aimed at promoting healing. This theory retains ideas from the SSDR framework in which behaviors that are inappropriate for the degree of threat imminence are inhibited in order to give way to appropriate behaviors (Fanselow, 1997). In addition, the theory offers a specific and testable framework regarding the factors that guide threat-related behaviors in rats and has received extensive empirical support over the years (for summaries, see Fanselow, 1994; Fanselow & Lester, 1988).

The most extensively investigated of those animal defensive behaviors is freez-ing, which consists of muscle tension and inhibition of all voluntary movement2 (Fanselow, 1984). This response occurs when a threat signal (CS) is encountered (i.e., threat detection), and has been studied from an associative learning per-spective. That is, Pavlovian conditioning procedures, where the animal is trained to associate a CS with an aversive US, are widely used in both animal and hu-man research because they elucidate processes that underlie the learning of threat signals.

Freezing occurs in safe places, meaning that the animal transitions from the position where the threat is detected to a quickly and easily accessible safer posi-tion where it freezes. Locomoposi-tion from the place of threat-detecposi-tion to the place of freezing can be regarded as a form of flight behavior (Fanselow, 1997; Fanselow & Lester, 1988). In fact, a form of flight has been observed within most de-fense reactions along the predatory imminence continuum and flight may play an important role in facilitating other defensive responses (Fanselow, 1997). Flight behavior physically increases the distance between the predator and the prey, thus clearly representing an avoidance response. Freezing also can be seen as an avoid-ance response since it diminishes the possibility of prey detection, thus providing protection, and therefore reduces the probability of aversive impact. As seen at the stage of pre-encounter, animals shape their behavior so that they can maxi-mize threat distance and consequently, minimaxi-mize interference with the preferred activity pattern.

An animal is able to rapidly switch between two avoidance response types; for example, from freezing (post-encounter) to an activity burst (circa-strike) and back (Fanselow, 1994; Fanselow, DeCola, & Young, 1993; Mobbs et al., 2007). When a warning signal is detected, threat imminence rises from the level of no predatory potential and the rat freezes, but the moment the negative consequence of that warning signal occurs (e.g., shock) the rat immediately engages in circa-strike behaviors (Fanselow, 1982) to return to freezing thereafter. Such rapid switching would only have been preserved through evolution if it offered a com-petitive advantage. The presence of fear-potentiated startle during freezing also suggests that the animal is prepared to rapidly engage in circa-strike behaviors at any moment, because startle has the ability to interrupt ongoing activity (Gra-ham, 1979) and allow the initiation of a more appropriate behavior. This offers support to the notion that a flight tendency is present even if the circa-strike be-havior of active flight is not being executed. That is, the threat imminence model suggests that the animal can be in a state of readiness for flight even when overt flight is not observed. The notion of a readiness to act is a critical factor in our TeARS model.

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Figure 2.1: Threat imminence continuum and response in the rat after Fanselow and Lester (1988) No predatory potential Predatory potential Predator detected Predator makes contact Predator makes the kill

Preferred activity pattern of nonaversively motivated behaviors Pre-encounter defensive behavior Post-encounter defensive behavior Circa-strike defensive bahavior Point of no return Recuperative behavior BEHAVIORAL CONSEQUENCE Increasing predatory imminence LEVELS

In summary, animal research suggests that threat activates a defensive mo-tivational network. Avoidance in the presence of threat is seen as evolutionarily predisposed, can be automatic and does not need shaping by instrumental learn-ing contlearn-ingencies. Thus, the organism is prepared for the execution of avoidance at the moment of threat encounter. Hereafter, we refer to such automatically primed readiness for avoidance as an avoidance tendency. The specific form of the response to threat depends on the imminence of threat, which can be actual (such as when a US is present) as well as anticipated (such as when a CS is present). Animals are prepared to engage in the extreme form of defense or avoidance (fight/flight circa-strike behaviors), but under lower levels of threat imminence, these are inhibited and other forms of threat avoidance (e.g., pre-encounter de-fense) are executed. We now examine the empirical support for similar phenomena in humans.

2.2.2 Evidence from human research

Threat stimuli are presumed to activate a defensive motivational network, which improves survival chances through ensuring protection, in contrast to positive stimuli that are presumed to activate an appetite motivational network, which

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ensures survival through supporting food procurement and procreation (Dickin-son & Dearing, 1979; Lang, 1995). These two opposing networks elicit opposing underlying action tendencies: approach and avoidance (Frijda, 1986) aimed at pro-tection or procurement, respectively. Responding guided by these networks can occur in three distinct domains: language-based subjective report such as ver-balized emotional experiences, psychophysiological responding such as the startle response, and behavior indicative of approach or avoidance (Lang, 1995; Lang & Davis, 2006).

Activation of the defensive motivational network in humans has been widely studied through the observation of physiological responses during passive viewing of pictures of different valence (Lang et al., 1997). It has been shown that defensive responses are primed when individuals are faced with stimuli of negative valence (Lang, Bradley, & Cuthbert, 1990). Multiple studies have demonstrated that star-tle is increased when humans passively view negative relative to positive images or neutral images (Lang, 1995; Lang et al., 1997). Potentiated startle in humans is a defensive response, which can interrupt ongoing behavior (Graham, 1979) that might be inappropriate to the level of threat present. Even though it has multiple components (Blumenthal et al., 2005), potentiated startle is commonly measured in the laboratory as the intensity of the reflexive eye blink to loud auditory stimuli (Blumenthal et al., 2005). This reflexive eye blink further protects the eye from injury (Graham, 1979). Similar startle potentiation is observed in rodents at the post-encounter stage of threat imminence (Fanselow, 1989). Lang and Bradley (2013) regard the physiological responses elicited under valenced conditions as serving a preparatory function for action to be undertaken, thus enabling rapid enactment of the action or, more specifically, rapid switching to approach and avoidance modes of responding. It has been shown that loud auditory stimuli, which provoke startle responses, are associated with a biphasic cardiac defense. The first acceleration/deceleration phase of heart rate serves to interrupt ongoing activity and initiate threat analysis, while the second phase prepares the organ-ism for action (Vila et al., 2007). Enhancement of the startle reflex and the heart rate pattern associated with it while passively viewing negative images provides indirect support for an automatic action tendency (or, priming of a particular action), akin to elevated startle during freezing at the post-encounter phase in rodents.

Despite the importance of the behavioral component of appetitive and defen-sive motivational networks, its priming has been overlooked until recently, mainly due to the lack of appropriate methodology for its study and the complexity of the phenomenon under question. In some animals, the only option for executing the action tendencies associated with each motivational system is instinctive and easily observable: reflexive approach (reducing the distance between the body and a pleasant object) and reflexive withdrawal (increasing the distance between the body and an unpleasant object) (Lang & Davis, 2006; Schneirla, 1959), which sim-plifies understanding of the behavioral impact of network activation. In humans, the networks are believed to guide behavior in a much more complex way (Lang & Bradley, 2013). For example, in some contexts when threat is not imminent, both the appetitive and defensive systems can be activated simultaneously and the observed behavioral patterns may be complex, creative and sometimes unpre-dictable (Bouton, Mineka, & Barlow, 2001; Lang, 1995; Lang et al., 1997) (e.g.,

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faking an illness to prevent attending school on the day of an exam). However, human behavior becomes more aligned with the defensive motivational state at high levels of threat imminence (Bouton et al., 2001; Lissek et al., 2006) when active fleeing is the only behavioral response that will definitely assure survival.

The issue of which response is selected when the defensive motivational net-work is activated in humans has been addressed but to a limited degree. Drawing from the work of Bolles and Fanselow, Lang et al. (Lang & Bradley, 2013; Lang et al., 1997) theorize that threat imminence is indeed the crucial factor deter-mining specific human behavioral responses, with defensive activation triggering alert behaviors during pre-encounter and focusing of attention and freezing at post-encounter. At this latter stage, it is proposed that physiological changes occur to prepare for the following stage where mobilization increases and action potentially occurs (circa-strike stage; Fanselow, 1989). Extending from their ani-mal work, Rau and Fanselow (2007) proposed that the functioning of individuals with post-traumatic stress exemplifies inappropriate activation of the adaptive defensive motivational network, as they react with post-encounter behavior when pre-encounter behavior is more appropriate and with circa-strike behavior at times when post-encounter behavior is the needed mode of defense. They attribute pat-terns of inappropriate responding to an inability to make correct threat-imminence judgments due to the trauma experience. Craske (1999; 2003) applied the model of threat imminence to human anxiety, and posited that predatory encounter parallels the individual’s detection of threat, and is associated with worry, mus-cle tension and avoidant behaviors, whereas the circa-strike behaviors parallel fear/panic and associated autonomic activation and escape behaviors. However, none of those models directly addresses the question of how a response is selected and which factors guide the execution of a particular behavior.

The strongest evidence for the role of threat imminence in humans comes from the work of Mobbs and colleagues (2009; 2007). Following evidence for the neu-rological pathways of defense responses in rodents (Fanselow, 1994; Fanselow et al., 1993), they examined activation of human brain regions while participants were playing a symbolic computer game where they could control the movement of a prey which was chased by a predator that administered electric shock to the participant upon symbolic contact. When the participant reduced the distance between the predator and the prey, brain activity increased in the periaquadec-tal gray, a brain region that controls reflexive responding; when the distance did not reduce, brain activity mostly occurred in the ventromedial prefrontal cortex (vmPFC, Mobbs et al., 2009, 2007). The neurological activation pattern for hu-mans was thus similar to that seen in rodents in reaction to imminent threat, with brain activation switching from evolutionarily newer to older brain structures as distance to the threat decreased (Fanselow, 1994). Recent work focused on the aspect of physical distance and its influence on the modulation of physiological defensive responses. It was observed that startle is potentiated by proximal pres-ence of objects and participants chose to maintain a larger distance of the self from threat predictors as compared to predictors of safety in both familiar and novel contexts (˚Ahs, Dunsmoor, Zielinski, & LaBar, 2015). Last, but not least,

this line of research showed that proximity enhances the valence of stimuli and the respective motivational network activation. Startle seems to be potentiated when avoidance is required and inhibited when endurance is required for

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predic-tors of shock at close distances (˚Ahs et al., 2015). Other evidence shows indirectly

that changes in threat distance might capture attention, with participants being much faster to categorize the approach of an angry face (aggressor/threat) than of a fearful face (victim, R. B. Adams, Ambady, Macrae, & Kleck, 2006; but see van Peer, Rotteveel, Spinhoven, Tollenaar, & Roelofs, 2009). However, no stud-ies to date have directly linked the neural or attentional mechanisms associated with distance from threat (i.e., threat imminence) with response selection and execution of behavioral responses.

2.2.3 Summary

Theories and findings on human defense responding reiterate many of the propo-sitions of the threat imminence model established in rodents. The robustness of the findings attests to the universality of defensive responding, the importance of threat imminence and the evolutionary advantage of rapid switching from less to more vigorous responding. However, empirical evidence has been limited to phys-iological, neurological and subjective responses, and has lacked measurement of behavioral responses (Beckers et al., 2013). Research from social and experimental psychology can offer clues about what shapes the behavioral response component of responding to threat. We will turn to that research in the next section.

2.3 Action tendencies

As already discussed, valenced stimuli can activate the appetitive or the defensive motivational network (e.g., Lang et al., 1997) and provoke the related action tendency of approach or avoidance. Gaining more insight into this phenomenon is crucial for a comprehensive understanding of threat-related responding and its regulation (Elliot, Eder, & Harmon-Jones, 2013). The concept of behavioral predispositions can be found in social psychology research on attitudes (seen as emotionally ridden ideas; Chen & Bargh, 1999) and emotions. Regardless of theoretical orientation, there is convergence on the idea that specific tendencies to act will correspond with the perceived motivational orientation of an encountered stimulus (i.e., defensive or appetitive), but that the primed action need not be executed (Elliot et al., 2013; Frijda, 2010). The expected consequence of exposure to a negative stimulus and corresponding defensive motivational orientation is the priming of an avoidance tendency (Eder & Hommel, 2013; Lang & Bradley, 2013). In other words, negatively valenced stimuli will limit the behavioral repertoire by activating the defensive motivational network and priming an avoidance tendency (much like their effect on rodents; Bolles, 1970), but will not precisely determine the manner in which that avoidance tendency would be executed in terms of its intensity and form. Response selection would be guided by other factors, discussed in later sections.

Two seminal studies set the stage for a detailed examination of activation of approach-avoidance tendencies in response to valenced material. The first in-structed participants to sort cards with positive and negative words by pushing them away (a motoric movement indicative of a defensive motivational state) or pulling them towards (a motoric movement indicative of an appetitive motiva-tional state) the body (Solarz, 1960). Participants who were required to respond

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to positive words with a pull movement and to negative words with a push move-ment were significantly faster than participants who responded in the opposite manner. The results were interpreted as evidence that motivationally compati-ble motoric movements (pull appetitive, push defensive) are executed faster, due to matching between stimulus valence and the movement. These findings were the first to empirically show that the mere presentation of a negatively valenced stimulus primes an avoidance tendency, with priming reflected in speed of re-sponding. Chen and Bargh (1999; but see Rotteveel et al., 2015) replicated and extended these findings using a different task. In two experiments, participants pushed or pulled a lever in response to positive or negative words with or without evaluating the meaning of the words. They concluded that valence of the words resulted in facilitation of either pulling (approach) or pushing (avoidance) regard-less of whether conscious evaluation of stimulus valence was required. Those data suggest that an avoidance tendency might emerge even in the absence of overt evaluative processing of threat.

The compatibility of approach and avoidance tendencies with positive and negative valenced stimuli, respectively, has since been corroborated in a number of studies using a variety of tasks and stimuli. In more recent versions of Chen and Bargh’s task, participants push or pull a joystick in response to computer-generated stimuli (joystick approach-avoidance task, JAAT), and in some versions of this task the image increases or decreases in size to strengthen the percep-tion of approach or avoidance (joystick approach-avoidance task with feedback, JAAT-F). This task has been used primarily with positive and negative words (e.g., Krieglmeyer & Deutsch, 2010), pictorial stimuli of positively and nega-tively valenced objects (Krieglmeyer & Deutsch, 2010; Rinck & Becker, 2007) and faces (e.g., Roelofs, Elzinga, & Rotteveel, 2005; Roelofs, Minelli, Mars, van Peer, & Toni, 2008; Vrijsen, Van Oostrom, Speckens, Becker, & Rinck, 2013) and the results have been consistent over studies. A recent meta-analysis of the effects of task, stimuli, valence and instructions on valence-action tendency com-patibility concluded that there is evidence for the link between valence and ap-proach/avoidance tendencies (possibly indirect with appraisals playing a crucial role; Phaf, Mohr, Rotteveel, & Wicherts, 2014).

Similar results have been obtained using a variant of the affective Simon task. In this task, participants emit verbal responses to valenced cues. Regardless of instructions to ignore the valence of the stimulus, responding to congruent trials (e.g., saying the word positive to a positive cue) is faster than incongruent trials (e.g., saying the word negative to a negative cue), even when responding on the basis of a stimulus dimension different from valence (e.g., saying positive to nouns and negative to adjectives). This so-called Simon effect has been extended to non-verbal responses of approach and avoidance (De Houwer, Crombez, Baeyens, & Hermans, 2001). With this methodology of moving a manikin either towards or away from a valenced word (manikin approach-avoidance task, MAAT; De Houwer et al., 2001), researchers also found that valence is differentially linked to action tendencies. Similar effects were obtained when pictorial stimuli are used within MAAT (e.g., Krieglmeyer & Deutsch, 2010). In addition, previously neutral stimuli that become conditioned stimuli through pairing with an aversive outcome (i.e., shock) prime an avoidance tendency in a modified MAAT when compared to neutral stimuli never paired with an aversive consequence (Krypotos

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et al., 2014). This finding suggests that approach-avoidance tendencies extend beyond innately aversive or innately appetitive stimuli to stimuli that acquire such properties through association; in other words, approach-avoidance tendencies can be learned. The crucial difference between the MAAT and the JAAT is that participants use a button press in order to approach or move away from the threat stimulus in the former paradigm. Thus, differential action tendencies towards both learned and innately valenced objects can be observed across behaviors that albeit topographically different (i.e., button press and joystick), function to withdraw from threat.

Finally, compatibility between a behavioral tendency of approach or avoidance and valence has also been examined using a movement platform that records small changes in distribution of body weight or full-body movements. Stins et al. (2011) found that participants were faster at initiating a step forward (approach) when faced with a portrait picture of a smiling face (positive valence) than of an angry face (negative valence); however, no significant difference was found for backward stepping (avoidance). Eerland, Guadalupe, Franken and Zwaan (2012) also found a preferential forward body leaning towards positive pictures and more backward leaning in response to negative pictures. One study on full-body movements, however, failed to find this compatibility effect (Stins, Lobel, Roelofs, & Beek, 2014). Last but not least, a recent study showed a backward displacement of body posture while viewing negative material relative to neutral material (Lelard et al., 2014). Thus, the compatibility of pleasant-approach and unpleasant-avoid has been extended to full-body responses, which may possess greater ecological validity than joystick or button press responses, although the results are not entirely consistent.

2.3.1 Mechanisms underlying approach-avoidance

compatibility effects

Three major hypotheses exist for why an approach tendency is primed by posi-tively valenced stimuli and an avoidance tendency by negaposi-tively valenced stim-uli. First, Cacioppo, Priester and Berntson (1993) and Chen and Bargh (1999) expanded the initial interpretation of motoric movement as an index of valence-primed action suggested by Solarz (1960) and argued that arm-flexion/extension (muscle activation as well as arm movement) is linked to valence. However, ob-servation of compatibility effects when using button presses rather than arm movements within tasks such as the MAAT argue against this hypothesis (see Krieglmeyer et al., 2013 for a more detailed account and Phaf et al., 2014 for a rebuttal of the flexion/extension account). In a recent meta-analysis of studies focusing on muscle activation, it was concluded that two other explanations of the compatibility effects are more convincing: namely the evaluative coding and distance regulation accounts (Laham, Kashima, Dix, & Wheeler, 2015).

The evaluative coding hypothesis suggests that valenced stimuli prime con-gruently valenced responses (Eder & Rothermund, 2008). In the Theory of Event Coding (TEC; Hommel, M¨usseler, Aschersleben, & Prinz, 2001; Lavender & Hom-mel, 2007), the label of the response required in the task as positive or negative (based on the situation, the task or current goals; Eder & Rothermund, 2008) determines what response will be primed. This theory was initially focused on

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ex-plaining goal-directed action and steered clear from the question of consciousness (Hommel et al., 2001). TEC was later expanded to explain affective compatibility by emphasizing the role of goals and intentions in action control, thus arguing against the automaticity of these valence compatibility effects (Lavender & Hom-mel, 2007). This theory prompted the introduction of feedback (i.e., zooming in and out of the stimulus) in JAAT, because feedback facilitates the labeling of motoric movements as approach or avoidance, and prevents participants from re-framing their pushing and pulling response as away from the body or towards the

body rather than the intended toward the object and away from the object (Rinck

& Becker, 2007). However, this account does not readily explain the observation of congruency effects with valence-irrelevant instructions, when participants are required to respond to another feature of the presented stimulus (Krieglmeyer & Deutsch, 2010; Krypotos et al., 2014) and when no valence labels are given to responses (Krieglmeyer, Deutsch, De Houwer, & De Raedt, 2010)(both tested within the MAAT).

Krieglmeyer, De Houwer and Deutsch (2011) investigated a third hypothe-sis, i.e., that distance change determines which response will be preferred. They proposed that every response that increases the distance from a negative object would be executed faster than any response that reduces this distance. The re-verse would occur for positive objects. Krieglmeyer et al. (2011) modified the MAAT such that initial responding was incompatible with the ultimate distance between the manikin and the object at the end of the trial (i.e., the manikin has to approach the object initially, in order to ultimately be further away from it). They found that ultimate distance was the factor that determined response speed. These results mirrored findings by Seibt et al. (2008), who found distance-change compatibility effects even when arm-flexion and extension were mismatched. Ref-erence frame also seems to have an effect on the compatibility findings (Saraiva, Schüür, & Bestmann, 2013); more specifically, the primed movements depend on whether participants receive self-referent (towards-away from the body) or object-referent (towards-away from the object) instructions. This suggests that the executed behavior can be quite flexible as long as it fulfills its distance regu-lating function. In addition, information-processing biases have been found on the basis of perceived or actual approach/avoidance. That is, individuals categorized positive words faster while performing or perceiving approach and negative words faster while performing or perceiving avoidance (Neumann & Strack, 2000). Thus, perception of distance change also primes the identification of the presence of a negative stimulus, even when the distance change is not controlled by the individ-ual. Finally, it has been recently shown that arm-flexion (indicative of a move-ment reducing the distance between the self and the object) increases appetitive physiological responding to positive stimuli (startle attenuation) and defensive re-sponding to negative stimuli (startle potentiation) as compared to arm-extension (Deuter, Best, Kuehl, Neumann, & Schächinger, 2014). In our view, the empirical evidence supports a distance change account above other accounts (as also argued by Krieglmeyer et al., 2013). This theory, further, closely matches motivational theories discussed earlier, in which activation of the defensive motivational net-work enables the organism to execute an avoidance action faster in order to assure survival by increasing the distance between the self and the threat.

Avoidance: From threat encounter to action execution - Thesis (complete)

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