Proactive interference and retrieval-induced forgetting in young adults with Social Anxiety Disorder.
Harry T. A. Moore
University of Amsterdam
August 27th, 2014
Supervisors: Elske Salemink1, Luis-Joaquín García-López2, & Carlos J.
Gómez-Ariza2.
Words: 7, 803
1 University of Amsterdam 2 University of Jaén
Abstract
Individuals with social anxiety disorder (SAD) suffer intense fear of negative evaluation and tend to focus on threatening features of social encounters. It has recently been suggested that deficits in memory control for stimuli which are not socially threatening may characterise the disorder (Gómez-Ariza et al. 2013).
However, the cognitive mechanism underlying poor memory control in SAD remains unclear. The present research compared young adults with and without SAD in their ability to resist proactive interference of material in working memory, and inhibition of the retrieval of irrelevant long-term memories. A within-between-subjects design compared the performance of 19 participants diagnosed with SAD and 56 non-clinical controls on a proactive interference task and retrieval-induced forgetting task. No retrieval-induced forgetting effect was found in either clinical or non-clinical participants. However, clinical participants were found to be more susceptible to proactive interference in working memory than control participants with low social anxiety. The findings are discussed in light of methodological shortcomings of the study and how our results can contribute to the understanding of memory control in SAD.
1. Introduction
The ability to suppress an intrusive thought or memory allows us to move on from traumatic events, maintain our well-being and focus on what we want or need to do in the present moment (Anderson & Huddleston, 2011). It may be the case that the ability to control irrelevant memories has implications for psychological
conditions where fearful avoidance is a chief concern; such as social anxiety disorder (SAD).
At the heart of SAD lies an intense fear of negative evaluation from other people and avoidance of feared situations (DSM-5; American Psychiatric Association, 2013). Individuals who suffer from SAD have been found to have difficulties
concentrating on what they are doing in the present moment (Bögels, Mulkens & de Jong, 1997) and to experience intrusive and repetitive memories of previous social encounters (Rachmann, Grüter-Andrew & Shafran, 2000). Clark and Wells’ (1995) cognitive model of social phobia posits that after socially anxious individuals have left a situation, they carry out a highly critical self-evaluation of their social
performance. The memory of previous social encounters leads socially anxious individuals to fear and avoid upcoming situations (Rapee & Heimberg, 2007). The field of experimental psychology has investigated how the cognitive processing of threatening situations contributes to social anxiety. However, one stone not yet turned is how the memory control of neutral non-threatening stimuli contributes to social anxiety.
It has been argued that individuals with SAD experience problems in memory control. Gómez-Ariza et al. (2013) found evidence to suggest that individuals with SAD are poor at selectively forgetting non-threatening memories. The authors used a
selective directed forgetting (SDF) procedure which initially required participants to memorise emotionally neutral information, and later try to forget a portion of the memorised information. Participants with SAD subsequently recalled more to-be-forgotten items than non-clinical participants. It is argued that in order to
successfully forget selected material, participants inhibited the retrieval of to-be-forgotten items (Delaney, Nghiem, & Waldem, 2009). However, the exact nature of the cognitive mechanisms underlying the SDF procedure remains a debate. Gómez-Ariza et al. suggested that SAD participants’ poor memory control was due to deficits in the executive control of non-threatening stimuli, although further research is needed to come to such a conclusion. Furthermore, the executive control of non-threatening stimuli in SAD is an area that is relatively under-researched compared to the cognitive processing of socially threatening stimuli in SAD. The present research concerns the cognitive control of non-threatening stimuli in SAD.
There is evidence to suggest that individuals with SAD have poor executive control of emotionally neutral stimuli. Executive functions are general cognitive control mechanisms such as set shifting, working memory control and inhibition which control the dynamics of cognitive processes (Miyake et al., 2000). Amir et al. (2011) found participants with Generalised Social Phobia3 (GSP) to perform worse on
a working memory control task than non-anxious control participants. Participants with GSP did not significantly differ from non-anxious control participants in their working memory control of threatening words. However, participants with GSP performed significantly worse on neutral stimuli than control participants which suggests that socially anxious individuals have poor working memory control of non-threatening stimuli. Furthermore, individuals with non-clinical social anxiety have
3 The term Generalised Social Phobia has now been replaced by the term ‘non-specific SAD’ since the
introduction of the DSM-5. Non-specific SAD refers to individuals diagnosed with SAD who fear and avoid most social situations (Heimberg et al., 2014).
been found to be more easily distracted to task-irrelevant information than anxious controls in a working memory control task which involved only non-threatening stimuli (Moriya & Sugiura, 2012). It is argued that SAD may be characterised by deficits in cognitive control of non-threatening stimuli.
There is also evidence to suggest that anxious individuals suffer from poor cognitive inhibition of non-threatening stimuli. Cognitive inhibition refers to the ability to over-ride a dominant response and the ability to resist interference from distracting information (Friedman & Miyake, 2004). Bishop (2009) found
individuals with high state and trait anxiety to have worse inhibitory control of distracting information and reduced prefrontal cortex activity during a response conflict task than participants with low state and trait anxiety. Deficits in cognitive inhibition were only found in anxious participants under conditions of low cognitive load, which may reflect the everyday difficulties in concentration which are
associated with clinical anxiety.
As there is evidence to suggest that individuals with SAD experience poor executive control in the domains of working memory and cognitive inhibition, we argue that they may also be susceptible to proactive interference (PI). Resistance to PI is the ability to select and recall recently encoded information in working memory without interference from other information that is no longer relevant (Lustig, May, & Hasher, 2001). In PI tasks participants typically listen to or read a series of stimuli and are instructed to either try to remember the stimuli or forget a portion of the stimuli. Friedman and Miyake (2000) found resistance to PI to involve a separate underlying mechanism to those involved in the inhibition of prepotent responses and resistance to distracting information. Furthermore, the ability to suppress intrusive thoughts was found to be related to resistance to PI, and not related to cognitive inhibition of prepotent responses or resistance to distracting information. This is of
particular interest to the present research as intrusive thoughts are symptomatic of SAD (Rachmann, Grüter-Andrew & Shafran, 2000). As resistance to PI is uniquely related to the ability to suppress intrusive thoughts we argue that individuals with SAD may have deficits in resistance to PI.
We argue that individuals with SAD also have deficits in inhibiting the retrieval of irrelevant long-term memories. Anderson, Bjork and Bjork (1994)
developed the retrieval-induced forgetting (RIF) paradigm to show how the retrieval of relevant memories leads to the suppression of the retrieval of irrelevant memories. Initially participants memorised a series of words and then later practiced retrieving a portion of the memorised words. In a later recall test of all of the words seen during the experiment, participants recalled more words which they had previously
practised retrieving than other unpractised words. However more interestingly, participants remembered fewer words which were similar to the words they had previously practised retrieving compared to words which were dissimilar. Anderson and colleagues argued that when participants practised retrieving certain words in the task they also inhibited the retrieval of other similar words. The inhibition of the retrieval of irrelevant memories made it more likely that they would subsequently be forgotten, which is known as the RIF effect. The RIF effect is of particular interest to the present study as it has been argued to involve the successful inhibition of
irrelevant memories (Anderson & Levy, 2009), and is therefore argued to have implications for individuals with SAD.
The findings from Gómez-Ariza et al. (2013) suggest that individuals with SAD have poor memory control and we argue that this is due to poor cognitive control of non-threatening stimuli. In order to follow up these findings, we argue that
individuals with SAD specifically have deficits in the resistance to PI in working memory, and are also unable to inhibit the retrieval of irrelevant memories. It is
argued that this research adds to the literature of SAD by highlighting two specific deficits in the cognitive control of non-threatening stimuli which have never before been investigated in SAD. Specifically we hypothesised that: 1) participants with SAD will show worse resistance to proactive interference than participants with low social anxiety, and that 2) participants with SAD will show a reduced ability to inhibit the retrieval of irrelevant memories while non-clinical control participants will be able to inhibit the retrieval of irrelevant memories.
2. Method
2.1. Participants
Seventy-six young Spanish adults (mean age = 20.79, S.D. = 1.95; 9 males) from the University of Jaén and the University of Córdoba originally participated in the study. Participants participated in return for course credits or for 6€. In order to be included in the experimental sample, participants had to meet the following inclusion criteria: 1) Meet diagnosis criteria for SAD (in order to be included in the
clinical group), 2) not currently undergoing any treatment for a pathology or
psychopathology, 3) between 18 and 25 years of age, and 4) Slept a minimum of 5 hours the previous night. 19 participants were included in the clinical group (Mean age = 21.53, SD = 1.81; 1 male) and 57 as non-clinical controls (Mean age = 20.54, SD = 1.95; 8 males).
In the clinical group, 19 participants were diagnosed with SAD based on DSM-IV criteria with an average clinical severity rating (CSR) of 4.79 (SD = 1.47). Of the 19 participants diagnosed with SAD, 3 participants exhibited comorbidity with
generalised anxiety disorder (GAD), and 1 participant exhibited comorbidity with GAD and major depressive disorder (MDD).
2.2. Measures
Anxiety Disorder Interview Schedule – Modified (ADIS-M; Valiente, Chorot, & Sandín, 2003). Adapted from the ADIS-IV-L (Brown, DiNardo, & Barlow, 1994)
which has been found to be a reliable tool for diagnosing SAD (Brown, DiNardo, Lehman & Campbell, 2001; García-López, Olivares, & Hidalgo, 2005), the ADIS-M is a semi-structured interview schedule which assesses current and lifetime
psychopathology according to DSM-IV criteria. Interviews were conducted by 2 clinical psychology undergraduate and 3 graduate students who were trained in a 12-hour workshop and supervised by a licensed psychologist. The interviews were conducted in Spanish. The social phobia section of the ADIS-M contains 13 items concerning the fear and avoidance of various aspects of every day social situations, e.g. eating in public. Participants must score 4 or greater of either fear of at least one situation (0 = no fear, 8 = very severe fear) or avoidance of at least one situation (0
= never avoids, 8 = always avoids) to be diagnosed with SAD. Participants are then
presented 13 SAD symptoms e.g. trembling or shaking. To qualify an appropriate diagnosis of SAD, participants must report one or more symptom severity rating of 4 or greater (0 = none, 8 = very severe) and score 4 or greater on a scale between 0 and 8 which is based on general distress and impairment caused in the participant’s everyday life. The order in which participants completed the interview and
questionnaire packet was counter-balanced between participants.
Beck Depression Inventory-II (II; Beck, Steer, & Brown, 1996). The
BDI-II measures somatic, emotional and cognitive symptoms of Major Depressive
Disorder (MDD; Arnau, Meagher, Norris, & Bramson, 2001). Participants rate their agreement with 21 items on a 4-point likert scale. For example, “Feelings of
punishment: 1) I don’t feel like I’m being punished 2) I feel like I may be punished 3) I hope to be punished 4) It feels like I am being punished.” The Spanish version has high internal consistency (α = .87) with a cut-off score of 19 (Sanz, Perdigón, & Vázquez, 2003). The BDI-II score is taken as the sum of all items.
Social Phobia and Anxiety Inventory-Brief (SPAI-B; García-López et al., 2008). SPAI-B is a brief version of the 45-item SPAI (Turner, Stanley, Beidel, &
Bond, 1989). Although the SPAI has good psychometric properties, the length of the questionnaire limits its practical utility. The SPAI-B measures cognitive, behavioural and somatic symptoms of social anxiety. Unlike the SPAI, the SPAI-B presents items with a different Likert scale format and less items, and does not use heterocentric language (Weiss, Hope, & Capozzoli, 2013).It has high internal consistency (α = .89) in Spanish young adults (Piqueras, Espinosa-Fernández, Garcia-Lopez, & Beidel, 2012). Participants are considered to not have social anxiety if they score lower than the cut-off score of 23, and those scoring higher are considered to have high social anxiety. Sixteen items are rated on a 5-point likert scale, for example, “I feel nervous when I have to speak in public (0 = never, 5 = always).” Items 15 and 16 are
comprised of sub-items related to somatic symptoms; hence item 15 is scored as an average of 4 sub-items, and item 16 as an average of 5 sub-items. The SPAI-B score is the sum of item ratings minus 16.
The Brief Fear of Negative Evaluation scale - Straightforward (BFNE-S; Rodebaugh et al., 2004). The BFNE is a brief version of the Fear of Negative
Evaluation Scale (Leary, 1983) which measures fear of negative evaluation by other people. The BFNE contains two factors: straightforward and reversed scored items. The BFNE-S only contains the straightforward items which has been found to have
high internal consistency (α = .89) among a Spanish speaking sample (Gallego, 2010). The BFNE-S has 11 items, for example, “I worry about what other people will think of me even when I know it doesn’t make any difference. (0 = not at all, 4 =
2.3. Materials
2.3.1. Retrieval Induced Forgetting (RIF) Task
Participants were issued the standardised instructions for the retrieval-induced forgetting (RIF) task, which was comprised of three phases. The first phase is the study phase in which participants are visually presented 36 syllable-word pairs (e.g. BA, Batalla) from 6 phonetic categories (Ca-, Ma-, Re-, Ba-, Di-, and Pe-) on a computer screen. Each phonetic category contains 6 words which each share the same first two letters (e.g. Batalla, Bacalao, Balanza, Bañera, Barrera and Basura from the category BA). In addition, participants are presented with 12 filler items, which are syllable-word pairs which participants will not be tested on in later phases of the experiment. The syllable-word pairs were non-socially threatening in nature and were taken from the orthographic syllable-word pairs used in Bajo et al. (2006). Bajo et al. ensured that the syllable-word stimuli met the following criteria: 1) a length between 2 and 5 syllables, 2) no obvious semantic or associative relationship existed between stimuli, and 3) the third letter within each word within each category was unique. Participants completed this phase in isolation. Participants were
instructed to try as hard as they could to memorise every syllable-word pair, as they would be asked to recall the pairs in a later phase of the experiment. Each syllable-word pair was presented for 5s in the centre of the computer screen, with a 1s
interval between each syllable-word pair. The order of stimuli was randomised across participants. The syllable was the first two letters of the accompanying word, e.g.
BA-Batalla. The syllable-word pairs were presented in blocks of 6 with no pause in
between, such that no syllable-word pairs from the same category appeared consecutively. One filler item proceeded and ended each block of 6 syllable-word pairs to reduce primacy and recency effects (Anderson, Bjork, & Bjork, 2000).
The second phase was the retrieval practice (RP) phase and participants were visually presented 18 syllable-letter stimuli in the centre of the computer screen (see Figure 2). The RP phase presented half of the stimuli which were presented in the first phase of the task. Participants were instructed to verbally recall the appropriate word when they saw the first three letters of the word. Participants first viewed the syllable for 2s, then a 1s interval, then the first three letters of the word for 6s. It was stressed that participants must try to recall the appropriate word without guessing. Participants practised retrieving each item 5 times in total. Hence, after the RP phase there were three levels of item practice: practiced items (Rp+), unpractised items from practised categories (Rp-), and unpractised items from unpractised categories (nRp). Participants were presented the stimuli in a randomised order. Participants completed this phase with the experimenter seated approximately 2m behind them, in such a way that they could not see the experimenter. The stimuli were presented in blocks of 3, with a filler item appearing before and after each block. Presentation of stimuli was counter-balanced across four versions of the task in such a way that 29 participants were presented with words from the categories Ca-, Ma-, and Re- in the RP phase, and 44 participants were presented with words from the categories Ba-, Di-, and Pe-.
Figure 2. Retrieval Practice phase of the retrieval-induced forgetting task.
In the third phase of the task participants completed a brief distractor task in isolation which required participants to complete 12 simple arithmetic problems within 5 minutes.
In the fourth phase of the task participants were presented with the recall test phase which consisted of a series of Remote Associates Tests (RAT; Mednick, 1962). In the RIF task, RAT trials measure implicit memory of items from previous phases of the task4. Participants were instructed that they would view three words in the
centre of the computer screen for a maximum duration of 60s. Participants were presented with three cue words and they had to find the solution which was a word
4Storm and Angello (2010) used RAT problems to show that inhibition underlies the ability to
overcome fixation during problem solving. Cognitive inhibition allows individuals to bypass fixation during problem solving, allowing them to generate new solutions (Smith, 2003). Storm and Angello (2010) found that RIF ability underlies the ability to solve RAT problems in that inhibition allows individuals to resolve competition between relevant memories and unwanted memories in long-term memory. As cognitive inhibition has been argued to underlie RIF and ability to solve RAT problems, we use RAT problems as an implicit recall test.
that was connected to each of the three cue words (e.g. board, magic, death, and solution: black). The cue words were not associated with each other. Out of 48 RAT trials, 9 of the solutions could be Rp+ items, 9 could be Rp- items, 18 could be nRp items, and 12 could be filler items. However, participants were not told that the solution was related to a previous phase or that it would be a word which they had previously seen in the experiment. Participants completed this phase in the presence of the experimenter and were not told whether their response was correct or not. This phase of the task was preceded by two practice trials in which participants were able to see the correct solution after having attempted to recall it, in order to make sure that participants correctly understood the task. We opted to use an implicit recall test to avoid the reinstatement of the category cues used during the retrieval practice phase and also because it presented items which had not been studied in any previous phase of the task. Finding the RIF effect using an implicit recall test would suggest that recall was due to inhibition during the retrieval practice phase and not due to presentation of the category cue (Perfect, Moulin, Conway & Perry, 2002).
The RIF effect was calculated as the mean difference between RAT problems correctly solved that had Rp- solutions and RAT problems correctly solved that had nRp- solutions. More specifically, as we counterbalanced item presentation in the RP phase across different versions of the task, Rp- items in one version essentially became an nRp- item in the counter-balanced version, and Rp+ items became nRp+ items in the counter-balanced version.
2.3.2. Proactive Interference (PI) Task
The PI task is used to measure the ability to prevent no longer relevant
information from interfering with relevant contents in working memory (Pimperton & Nation, 2010). Participants were told that they would be audibly presented a series of words, some of which they would have to ignore according to the presentation of a visual stimulus in the centre of the computer screen.
The audible word stimuli which participants had to attend to were presented in two blocks of 12 trials, separated by a short break. The stimuli were separated into single and double trials. In single trials participants listen to a series of 3 words and in double trials participants listened to 6 words (See Figure 3). Both single and double trials were always followed by a question which concerned the words in each trial, for example, “Was the colour you heard ‘brown’?” Participants responded to the question with either “Yes,” or “No.” Double trials were separated by the visual
stimulus, ‘xxxxxx’, which appeared in the centre of the computer screen for 1s. Participants were instructed to ignore the words which they heard before the visual stimulus, as they will always have to answer a question concerning the words which they hear after the visual stimulus. Each trial was followed by the visual cue ‘¿?’ which prompted participants to press the spacebar on the computer keyboard in order to hear a question about the trial that they had just been presented.
Participants were never told whether their response was correct or incorrect.
Double trials were separated into two conditions of interference trials or control trials. Interference trials were such that the correct response to the question was a word presented before the visual stimulus. As participants were required to ignore the words which they heard before the visual stimulus, an interference trial required a sufficient level of resistance to proactive control in order to inhibit the
previously encoded words from interfering with the response to the question. Control trials were such that the correct response to the question was a word presented after the visual stimulus. As participants did not have to try to ignore the word it would not produce any interference with working memory. Interference trials provided an index of proactive interference. In total, participants were presented 8 single trials, 8 double interference trials and 8 double control trials. The position in which the correct word appeared in trials was counterbalanced to reduce recency and primacy effects. Participants completed 6 practice trials before beginning the task to ensure they fully understood the demands of the task. Participants performed the task in isolation in a laboratory cubicle.
2.4. Procedure
Participants were initially invited to an interview where they completed the questionnaire packet and interview, in which the order was counter-balanced across participants. Participants were then selected to participate in the experimental phase of the study based on a positive diagnosis of SAD or above threshold for SPAI-B.
Upon entering the laboratory, participants were issued with the general
instructions of the experiment and gave full written consent. The study was approved by the University Research Ethics Committee, in compliance with the Code of Ethics of the World Medical Association (Declaration of Helsinki) and the Charter of
Fundamental rights of the European Union. Participants were required to provide information concerning their previous night’s sleep as it has been argued that few hours of sleep can hinder memory control (Anderson & Huddleston, 2011).
Participants performed the experiment seated in an isolated laboratory cubicle. Participants then completed the RIF task and PI task. The order in which participants were presented the RIF and PI tasks was counter-balanced across participants. Upon completion of the study, participants were given a full debrief before being thanked for their time.
2.5. Data Analysis
Participants were excluded from analysis of the RIF task if they reported that they correctly guessed the true nature of the task, if they reported that they applied effort less than 5 (0 = applied no effort at all, 10 = applied a lot of effort), or if they scored a Z-score of greater than 3. Participants were removed from analysis of the PI task if they scored a Z-score of 2.5 or greater. Z-scores were calculated according to each task; hence some participants’ data were included in the RIF task or the PI task. The RIF Z-score was calculated according to nRp- items, and the PI Z-score was calculated according to interference trials. In the RIF task 2 participants were
removed from the data because they reported a Z-score of nRp- items greater than 3, and 10 were removed either because they reported that they understood the true nature of the study or because they made no effort to comply with the instructions of the task. In the PI task 3 participants were removed from the data because they reported a Z-score of greater than 2.5.
Due to the strict exclusion criteria of the RIF task, we were left with a larger sample size in the PI task before removing participants according to our Z-score exclusion criteria. This allowed us to exclude participants according to a stricter Z-score of 2.5 in the PI task. Furthermore, as we were left with a larger sample size in the PI task we were able to compare means according to different levels of social anxiety. We compared participants according to diagnosis and terciles of SPAI-B scores which left us with non-patient controls with very low or very high social anxiety. We were not able to separate participants in the RIF task according to terciles due to the small sample size left after removing participants according to our exclusion criteria. Thus, in the RIF analysis means were compared according to
diagnosis and SPAI-B cut-off score. The scores on both the RIF and PI tasks were analysed as percentages.
A 2 (retrieval practice status: Rp- vs. nRp-) x 3 (social anxiety: SAD vs. low vs. high) repeated measures ANOVA tested the hypothesis that participants with SAD would not be able to inhibit the retrieval of irrelevant information in the RIF task, and that control participants would be able to inhibit the retrieval of irrelevant information. A one-way ANOVA (group: SAD vs. lower SPAI-B tercile vs. middle SPAI-B tercile vs. upper SPAI-B tercile) tested the hypothesis that participants with SAD would be less able to resist PI than control participants with low social anxiety. An ANCOVA showed the amount of variance in the PI task that was due to
depression symptoms. Separate linear regression analyses showed the relationship between SAD, fear of negative evaluation and depression symptoms with RIF and resistance to PI. The significance level of .05 was used for all analyses.
3. Results
3.1 Preliminary analysis; inhibition of irrelevant memories.
The final sample (see Table 1) in the RIF task included 62 participants: 15 clinical participants based on the ADIS-M, 22 participants with low social anxiety and 25 participants with high social anxiety. Participants slept on average 7 hours (SD = 1.08) the night before the experiment took place. Participants exerted an average effort of 8.92 (SD = 1.02) out of a possible 10, and reported an average difficulty level of 6 (SD = 2.14) out of a possible 10. A one-way ANOVA (task version: version 1 vs. 2. vs. 3 vs. 4) was carried out to show if participants differed in
performance across 4 different versions of the RIF task. A main effect of task version was found on recall of nRp items, F (3, 69) = 2.74, MSE = 193.45, p = .05, = .11. A one-way ANOVA (task order: RIF task before PI task vs. PI task before RIF task) was carried out to control for task order effects. No main effect of task order on recall of nRp items was found, F (1, 71) = .84, MSE = 207.92, p = .36, = .01.
Table 1.
Demographic information and questionnaire measures for participants who were included in retrieval-induced forgetting analysis5.
Clinical SAD Non-clinical control
Low social anxiety High social anxiety
N 15 22 25 % Female 100 90.90 88 Age 21.93 (1.75) 20.18 (1.44) 20.40 (1.53) SPAI-B 32.68 (10.10) 10.25 (6.39) 33.85 (7.76) BFNE-S 16.43 (6.98) 6.95 (5.14) 18.12 (8.41) BDI-II 12.29 (9.24) 9.14 (9.97) 15.48 (9.56) Severity 4.76 (1.56) - - Comorbidity 3 GAD 1 GAD/MDD - -
Means of Age, SPAI-B, BFNE-S, BDI-II, & SCR; Comorbidity frequency; Standard deviations are displayed between parentheses. T-tests performed between clinical and non-clinical groups. SPAI-B: Social Phobia and Anxiety Inventory-Brief. BFNE-S: Brief Fear of Negative
Evaluation-Straightforward. BDI-II: Beck’s Depression Inventory-II. Severity refers to severity rating according to the diagnosis. GAD: Generalized Anxiety Disorder. MDD: Major Depressive Disorder.
3.1.1 Preliminary analysis; facilitation effects
A one-way ANOVA (group: SAD vs. low non-clinical social anxiety vs. high non-clinical social anxiety) was carried out to make sure that all participants performed well during the retrieval practise of the task. There was no significant main effect of social anxiety on recall accuracy during the retrieval practice phase, F (2, 59) = .907, MSE = 465.04, p = .41, = .03. Furthermore, there was no
5 Demographic information in Table 1 displays data after outliers were removed according to Z-scores
significant main effect of group on all correct RAT trials in the final phase of the RIF task, F (2 ,59) = 1.48, MSE = 208.48, p = .24, = .05, which shows that groups did not differ in overall performance in the final phase of the task.
We then compared recall for practised items (Rp+) and unpractised items (nRp+) items across different groups of social anxiety. As neither Rp+ items nor nRp+ items are to-be-inhibited items, we expected all participants to show a
facilitation effect: greater recall of Rp+ items than nRp+ items which demonstrates the enhanced memory of Rp+ items due to retrieval practice. A 2 (retrieval practice status: Rp+ vs. nRp+) x 3 (group: SAD vs. low vs. high) repeated measures ANOVA was carried out to investigate facilitation effects. A significant interaction effect was found between group and retrieval practice status, F (2, 59) = 4.66, MSE = 351.25, p < .05, = .14 (see Table 2). Polynomial contrasts indicated no significant facilitation effect in non-clinical participants with low social anxiety, F (1, 21) = 3.37, MSE = 367.30, p = .08, = .14, nor in non-clinical participants with high social anxiety, F (1, 24) = 1.96, MSE = 363.79, p = .17, = .08. However, clinical participants recalled more nRp+ items than Rp+ items which indicated a significant reverse facilitation effect, F (1, 14) = 5.39, MSE = 305.70, p < .05, = .28. No significant main effect of social anxiety on retrieval practice was found.
Table 2. Means and standard deviations of performance in the final phase of the
RIF task.
RIF Non-clinical controls
Clinical SAD Low social anxiety High social anxiety Rp+ (%) 40.74 (24.37) 50.00 (27.80) 42.74 (25.47) Rp- (%) 22.22 (20.14) 27.27 (19.62) 16.67 (10.06) nRp+ (%) 55.56 (29.10) 39.40 (19.91) 35.90 (20.44) nRp- (%) 22.22 (13.93) 26.26 (15.16) 19.67 (15.17)
3.2. Retrieval-induced forgetting effects
In order to test the hypothesis that participants with SAD are less able to inhibit the retrieval of irrelevant memories compared to non-clinical control participants a 2 (retrieval practice status: Rp- vs. nRp-) x 3 (social anxiety: SAD vs. low vs. high) repeated measures ANOVA showed a marginally significant main effect,
F (2, 59) = 2.76, MSE = 293.69, p = .07, = .09, and pairwise comparisons
indicated a significant difference between participants with low and high social anxiety, t (3) = 2.35, SE = 3.54, p < .05, although no significant differences between low social anxiety and clinical participants t (3) = 1.12, SE = 4.06, p = .27, nor
between high social anxiety and clinical participants t (3) = .95, SE = 3.96, p = .34. Inconsistent with our hypothesis, no significant interaction effect was found between retrieval practice status of RAT item and level of social anxiety, F (2, 59) = .26, MSE = 205.96, p = .77, = .01 (see Figure 4).
Figure 4. Means and standard errors of RIF task.
3.1.3. Relationship between symptomatology and RIF
To explore the relationship between RIF and social anxiety and depression symptoms a standardised difference in means was calculated by subtracting the percentage of Rp- RAT items solved by the percentage of nRp- RAT items solved, and dividing the result by the percentage of nRp- RAT items solved. To investigate the relationship between social anxiety and depression symptoms, we carried out three separate linear regression analyses of SPAI-B (r = .07, t (72) = -.55, p = .59), BFNE-S (r = .02, t (71) = -.15, p = .88) and BDI-II (r = .12, t (71) = 1.03, p = .31) scores on the standardised RIF effect which gave no significant correlations.
3.2. Resistance to Proactive Interference (PI)
The final sample (see Table 3) included 74 participants, 19 clinical
participants, 17 in the lower tercile of SPAI-B scores, 19 participants in the middle tercile and 17 participants in the upper tercile. Overall, participants produced the
correct response to interference trials approximately 85% of the time (Mean = 85.96, SD = 25.85). A one-way ANOVA (task order: RIF task before PI task vs. PI task before RIF task) was carried out to control for task order effects. No main effect of task order on interference trials was found, F (1, 71) = .53, MSE = 677.26, p = .47, = .01.
Table 3.
Demographic information and questionnaire measures for participants who were included in proactive interference analysis 6.
Means of Age, SPAI-B, BFNE-S, BDI-II, & SCR; Comorbidity frequency; Standard deviations are displayed between parentheses. t-tests performed between clinical and non-clinical groups. SPAI-B: Social Phobia and Anxiety Inventory-Brief. BFNE-S: Brief Fear of Negative
Evaluation-Straightforward. BDI-II: Beck’s Depression Inventory-II. Severity refers to severity rating according to the diagnosis. GAD: Generalized Anxiety Disorder. MDD: Major Depressive Disorder.
6 Demographic information in Table 2 displays data after outliers were removed according to Z-scores
for the PI task.
Clinical SAD SPAI-B terciles
Lower Middle Upper
N 19 17 19 17 % Female 94.74 82.35 78.95 94.12 Age 21.53 (1.81) 20.53 (1.37) 19.84 (1.21) 20.88 (1.76) SPAI-B 30.00 (11.03) 6.38 (2.79) 22.62 (4.70) 38.26 (5.56) BFNE-S 15.06 (7.25) 5.35 (4.23) 12.21 (7.63) 20.24 (8.00) BDI-II 11.72 (8.80) 4.88 (6.44) 13.63 (7.90) 16.53 (9.87) Severity 4.68 (1.49) - - Comorbidity 3 GAD 1 GAD/MDD - -
To test the hypothesis that participants diagnosed with SAD would show worse resistance to PI than non-patient controls a one-way ANOVA (group: SAD vs. lower SPAI-B tercile vs. middle SPAI-B tercile vs. upper SPAI-B tercile) was carried out on percentages of correct responses in interference trials (see Table 4 for means). Confirming our hypothesis there was a marginally significant main effect of group on interference trials, F (3, 68) =2.16, MSE = 515.62, p = .05, = .09. Planned
comparisons were conducted to investigate the difference between each SPAI-B tercile group and clinical participants in interference trials. No significant differences were found between interference scores of the clinical participants and non-clinical participants, t (68) = .62, SE = 19.62, p = .27, however there was a significant difference between clinical participants and the lower SPAI-B tercile, t (68) = 1.78,
SE = 6.08 p < .05, and between participants in the lower and middle SPAI-B tercile, t
(68) = 2.27, SE = 7.66, p < .05, and between participants in the middle and upper SPAI-B tercile, t (68) = 1.75, SE = 8.27, p < .05, which confirms our hypothesis that participants with SAD show worse resistance to PI than participants with low social anxiety. No significant main effect of group on control trials was found.
Table 4. Means and standard deviations of proactive interference task.
Proactive Interference SPAI-B terciles
Clinical SAD Low Middle High
Single (%) 98.68 (3.94) 100.00 (.00) 92.36 (24.68) 98.53 (4.15) Control (%) 98.03 (4.68) 99.27 (3.03) 93.06 (18.30) 97.06 (7.03) Interference (%) 85.53 (25.77) 96.32 (5.87) 78.95 (32.82) 93.38 (14.06)
3.2.1. Relationship between symptomatology and PI
To examine the relationship between resistance to PI and social anxiety symptoms, a linear regression of SPAI-B scores on interference scores confirmed that the
relationship between was nonlinear, r = .10, t (74) = .89, p = .38. There was no significant correlation between BFNE-S scores and performance on interference trials, r = .09, t (73) = -.73, p = .50, although there was a marginally significant correlation between BDI-II scores and performance on interference trials, r = .22, t (73) = -1.93, p = .06. In order to assess the covariance of depression on the main effect of social anxiety group on interference trials, a one-way ANCOVA (group: SAD vs. lower SPAI-B tercile vs. middle SPAI-B tercile vs. upper SPAI-B tercile) was carried out. The ANCOVA analysis showed a marginally significant main effect of social anxiety on interference trials, F (3, 66) = 1.95, MSE = 477.70, p = .06, = .07, and significant covariate of BDI-II scores, F (1, 66) = 7.34, MSE = 3529.53, p < .01, = .09. However, as there was a significant main effect of social anxiety group on BDI-II scores, F (3, 67) = 6.03, MSE = 419.14, p < .01, = .21 (see Table 3 for means), an ANCOVA cannot attribute unexplained variance of social anxiety on interference trials to depression.
4. Discussion
The aim of this research was to investigate the deficits in two types of
cognitive control of non-threatening stimuli which has never before been studied in the context of SAD. It has been argued that SAD is characterised by poor memory control of non-threatening stimuli (Gómez-Ariza et al., 2013), although the
underlying cognitive processes had not yet been uncovered. The present findings add to the literature of SAD by providing evidence of a specific deficit in the resistance to PI of non-threatening stimuli in working memory in individuals with SAD.
Our findings add to cognitive models of SAD which suggest that patients are less able to control repetitive and intrusive unwanted cognitions (Clark & Wells, 1995) by suggesting that cognitive deficits in SAD also extend to non-threatening stimuli. Furthermore, our findings provide evidence of a very specific deficit in resistance to PI which involves an underlying cognitive mechanism that is distinct from prepotent response inhibition and resistance to distracting information (see Friedman & Miyake, 2004). However, we only provide evidence of individuals with SAD having deficits in verbal resistance to PI while non-verbal resistance to PI has not yet been investigated in the context of SAD. From a clinical perspective there are reasons to suggest that individuals with SAD may have deficits in both verbal and non-verbal domains of resistance to PI in working memory. Baddeley’s (2007) multi-component model of working memory posits that working memory is made up of two sub-systems: the phonological loop and the visuospatial sketchpad. These two
systems are responsible for short-term memory storage of verbal and visual
information and are run by the over-arching central executive. Eysenck, Payne and Derakshan (2005) found evidence that anxiety symptoms are detrimental only to the central executive on a non-verbal working memory task, leaving the visual and verbal
domains of working memory intact. However, theoretical accounts of social anxiety suggest that individuals with SAD may also have deficits in non-verbal cognitive processes. Evidence from post-event processing in SAD suggests than visual imagery can prove both positive and detrimental to anxiety symptoms (Brozovich &
Heimberg, 2013), and repetitive and intrusive images can interfere with concentration in SAD (Rachmann, Grüter-Andrew, & Shafran, 2000).Future research should follow up our findings on resistance to PI by using verbal and non-verbal versions of the PI task (see Pimperton & Nation, 2010) to understand the domain-specific nature of the working memory deficit in SAD.
Regarding our second hypothesis, we found no evidence to suggest that
participants with SAD are poor at inhibiting the retrieval of irrelevant memories. The results from the RIF task showed no RIF effect in participants with SAD or non-patient controls. Furthermore, we observed a reverse facilitation effect in
participants with SAD, and no facilitation effect in non-clinical controls. The facilitation effect is the greater recall of items which have been subject to retrieval practice (Rp+) than items which have not been subject to retrieval practise (nRp). The facilitation effect is due to retrieval practice and not due to the inhibition of irrelevant items (Rp-). This is strong evidence to suggest that the RIF task did not function as expected in the present study which limited the extent to which the hypothesis could be tested. Furthermore, there was no RIF effect found in participants with SAD or non-clinical controls. Although there is currently no research which has measured participants’ social anxiety and RIF, it would be expected that participants with no reported pathology would have no problems in inhibiting the retrieval of irrelevant memories (see Anderson & Huddleston, 2011). Participants’ over-all performance on the implicit recall test was also much lower
than previous research which has administered the RIF task with an implicit recall test (e.g. Del Preste et al., in press). This may be due to participants not fully
understanding the demands of the RIF task. In a previous study which used the same RIF procedure (Del Preste et al.) participants were explicitly told that the solutions to the implicit recall task would be related to previous phases of the RIF task. This may have made participants less likely to perform well in the RIF task in the present study. In addition, although there were four versions of the RIF task created to avoid biased recall of stimuli, we still found participants to perform significantly better on some versions of the task than others.
There are other studies which have found a lack of RIF in populations known to have deficits in inhibitory control (see Storm & Levy, 2012). It may be the case that inhibition is not an all-or-none function of cognitive control. This means that there may be situations where samples with deficits in cognitive inhibition perform better or worse in tasks which involve inhibition. Ortega et al. (2012) found older
participants suspected of having poor cognitive inhibition to show a decreased RIF effect compared to young participants only when cognitive load was increased during dual-task conditions. As we hypothesised that participants with SAD would show a decreased RIF effect due to poor cognitive inhibition, it may be the case that
individuals with SAD only show a decreased RIF effect when cognitive load is high.
Our findings have implications for treatments which aim to decrease anxiety symptoms in SAD. As we have found evidence of deficits in resistance to PI in working memory, training programmes designed to improve working memory control may benefit individuals with SAD. Working memory training programmes have been used effectively on other clinical samples such as reducing ADHD symptoms in children and adolescents (Shipstead, Redick, & Engle, 2012 for a
review). There is also evidence to suggest that working memory training reduces intrusive thoughts and rumination (Bomyea & Amir, 2011), although this evidence is limited as it does not come from a randomised clinical trial. Furthermore, task concentration training has been found to reduced social anxiety symptoms (Bögels, Mulkens, & de Jong, 1997), as well as task concentration training in corroboration with mindfulness training in SAD (Bögels, Sijbers, & Voncken, 2006). Future research should investigate how the specific improvement in resistance to PI in working memory can improve SAD symptoms.
An alternative explanation of our findings is that individuals with SAD are overcome by worry and rumination which hinders working memory control of non-threatening information. This is in line with the Attentional Control Theory
(Eysenck, Derakshan, Santos, & Calvo, 2007) which posits that anxious individuals’ executive control resources are overwhelmed by their anxious state which impedes their ability to operate in a goal-directed manner. However, participants in the present study completed the PI task in isolation and gave various self-reported measures of social anxiety. No feedback was given of participants’ performance before, during or after the PI task which leaves little evidence to suggest that clinical participants’ low performance was due to a heightened state of anxiety or
preoccupation. However, future research should control for worry and preoccupation by directly asking participants how concerned they were by judgement from the experimenter. Future research could also control for anxiety symptoms by taking physiological measures of stress and anxiety in order to observe how anxiety symptoms deviate from a baseline state before and after the experiment. Another alternative interpretation of our findings is that deficits in resistance to PI were due to depression. We found participants with SAD to perform poorer on the PI task than
participants with low social anxiety, although participants with SAD were also found to be significantly more depressed than participants with low social anxiety. This makes it difficult to separate differences in resistance to PI which may be caused by social anxiety or depression. SAD and MDD are both characterised by repetitive and intrusive thoughts and there is evidence to suggest that the ability to suppress
intrusive thoughts is related to resistance to PI (Friedman & Miyake, 2004). Future research should investigate resistance to PI in SAD further by comparing individuals with SAD and non-patient controls with sub-threshold depression scores, in order to be able take into account the role of depression in resistance to PI and SAD.
It must be noted that there are limitations to the present research. Firstly, analysis of the PI task suggests possible ceiling effects due to the high success rates on interference trials in all groups of participants which explains the absence of significant differences between participants with medium and high social anxiety and clinical participants in the PI task, although participants with low social anxiety were found to perform significantly better than clinical participants. It may be the case that the PI task used in the present research was not sensitive in differentiating abilities in resistance to PI in a young-adult sample as it was adapted from a study on children of 7-8 years of age (Pimperton & Nation, 2010). Future research should administer a task which might be more sensitive to small differences between groups of low, medium and high working memory control abilities. Secondly, the clinical sample in the present research included participants with SAD comorbid with GAD and MDD. SAD overlaps greatly in terms of both neurology and symptomatology with MDD (Brown et al., 2001; Hamilton et al., 2014) and GAD (Blair et al., 2012). In order to be able to attribute poor resistance to PI to SAD symptoms, future research
should administer the PI task on separate groups with non-comorbid SAD, GAD and MDD to compare working memory control between psychopathologies.
We argue that it is necessary to replicate our findings that individuals with SAD show poor resistance to PI, and observe the activity of neurological structures involved in the resistance to PI in a clinical sample. Observing deficits in the
activation of neurological structures responsible for resistance to PI would show us to what extent SAD is characterised by deficits in prefrontal processing of non-threatening stimuli as well as behavioural deficits. To conclude, the present research provides novel evidence that SAD is characterised by deficits in resistance to PI of non-threatening stimuli in working memory. We still do not know the extent to which this deficit is specific to resistance to PI, or whether it extends to other aspects of the cognitive control of non-threatening stimuli. Further research is needed to understand the extent to which deficits in resistance to PI maintain SAD.
References
American Psychiatric Association. (2013). Diagnostic and statistical manual of
mental disorders (5th ed.). Arlington, VA: American Psychiatric Publishing.
doi: 10.1176/appi.books.9780890425596.744053.
Amir, N., & Bomyea, J. (2011). Working memory capacity in generalized social phobia. Journal of Abnormal Psychology, 120, 504-509. doi:
10.1037/a0022849.
Anderson, M. C., Bjork, E. L., & Bjork, R. A. (2000). Retrieval-induced forgetting: Evidence for a recall-specific mechanism. Psychonomic Bulletin & Review, 7, 522-530. doi: 10.3758/BF03214366
Anderson, M. C., Bjork, R. A., & Bjork, E. L. (1994). Remembering can cause
forgetting: Retrieval dynamics in long-term memory. Journal of Experimental
Psychology: Learning, Memory, and Cognition, 20, 1063-1087. doi:
10.1037/0278-7393.20.5.1063.
Anderson, M. C., & Huddleston, E. (2011). Towards a cognitive and neurobiological model of motivated forgetting. In True and False Recovered Memories:
Toward a Reconciliation of the Debate, Nebraska Symposium on Motivation.
doi: 10.1007/978-1-4614-1195-6_3.
Anderson, M. C., & Levy, B. J. (2009).Suppressing unwanted memories. Current
Directions in Psychological Science, 18, 189-194. doi:
Arnau, R. C., Meagher, M. W., Norris, M. P., & Bramson, R. (2001). Psychometric evaluation of the Beck Depression Inventory-II with primary care medical patients. Health Psychology, 20,112-9. doi: 10.1037/0278-6133.20.2.112 Aron, A. R., Fletcher, P. C., Bullmore, E. T., Sahakian, B. J., & Robbins, T. W. (2003).
Stop-signal inhibition disrupted by damage to right inferior frontal gyrus in humans. Nature Neuroscience, 6, 115-116. doi: 10.1038/nn1003.
Baddeley, A. (2007). Working memory, thought, and action. Oxford: Oxford University Press.
Bajo, T. M., Gómez-Ariza, C. J., Fernandez, A., & Marful, A. (2006). Retrieval-induced forgetting in perceptually driven memory tests. Journal of
Experimental Psychology: Learning, Memory and Cognition, 32, 1185-1194.
doi: 10.1037/0278-7393.32.5.1185.
Beck, A. T., Steer, R. A., & Brown, G. K. (1996). Manual for the Beck Depression
Inventory-II. San Antonio, TX: Psychological Corporation.
Bishop, S. J. (2009). Trait anxiety and impoverished prefrontal control of attention.
Nature: Neuroscience, 12, 92-98. doi; 10.1038/nn.2242.
Blair, K. S., Geraci, M., Smith, B. W., Hollon, N., DeVido, J., Otero, M., Blair, J. R., & Pine, D. S. (2012). Reduced dorsal anterior cingulate cortical activity during emotional regulation and top-down attentional control in generalized social phobia, generalized anxiety disorder, and comorbid generalized social
phobia/generalized anxiety disorder. Biological Psychiatry, 72, 476-482. doi: 10.1016/j.biopsych.2012.04.013.
Bögels, S. M., Mulkens, S., & De Jong, P. J. (1997). Task concentration training and fear of blushing. Clinical Psychology and Psychotherapy, 4, 251-258. doi: 10.1002/(SICI)1099-0879(199712)4:4
Bögels, S. M., Sijbers, G. F. V. M., & Voncken, M. (2006). Mindfulness and task concentration training for social phobia: a pilot study. Journal of Cognitive
Psychotherapy, 20, 33-44. doi: 10.1891/jcop.20.1.33.
Bomyea, J., & Amir, N. (2011). The effect of an executive functioning training program on working memory capacity and intrusive thoughts. Cognitive
Therapy Research, 35, 529-535. doi: 10.1007/s10608-011-9369-8.
Brown, T. A., Campbell, L. A., Lehman, C. L., Grisham, J. R., & Mancill, R. B. (2001). Current and lifetime comorbidity of the DSM-IV anxiety and mood disorders in a large clinical sample. Journal of Abnormal Psychology, 110, 585-599. doi: 10.1037/0021-843X.110.4.585.
Brown, T. A., DiNardo, P. A., & Barlow, D. H. (1994). Anxiety Disorders Interview
Schedule for DSM-IV (ADIS-IV. San Antonio, TX: Psychological Corporation.
Brozovich, F., & Heimberg, R. G. (2008). An analysis of post-event processing in social anxiety disorder. Clinical Psychology Review, 28, 891-903. doi: 10.1016/j.cpr.2008.01.002
Brozovich, F., & Heimberg, R. G. (2013). Mental imagery and post-event processing in anticipation of a speech performance among socially anxious individuals.
Behavior Therapy, 44, 701-716. doi: 10.1016/j.beth.2013.07.001.
Clark, D. M., & Wells, A. (1995).A cognitive model of social phobia. In R. Heimberg, M.
Eysenck, M. W., Derakshan, N., Santos, R.., & Calvo, M. G. (2007).Anxiety and cognitive performance: Attentional control theory. Emotion, 7, 336-353. doi: 10.1037/1528-3542.7.2.336
Eysenck, M. W., Payne, S., & Derakshan, N. (2005). Trait anxiety, visuospatial
processing, and working memory. Cognition and Emotion, 19, 1214-1228. doi: 10.1080/02699930500260245.
Friedman, N. P., & Miyake, A. (2004). The relations among inhibition and interference control functions: A latent-variable analysis. Journal of
Experimental Psychology, 113, 101-135. doi: 10.1037/0096-3445.133.1.101
Friedman, N. P., Miyake, A., Robinson, J. L., & Hewitt, J. K. (2011). Developmental trajectories in toddlers’ self-restraint predict individual differences in
executive functions 14 years later: a behavioral genetic analysis.
Developmental Psychology, 47, 1410-1430. doi: 10.1037/a0023750.
Gallego Pitarch, M. J. (2010). Brief version of the fear of negative evaluation scale – straightforward items (BFNE-S): Psychometric properties in a Spanish population. The Spanish Journal of Psychology, 13, 981-989.
Garcia-López, L. J., Hidalgo, M. D., Beidel, D. C., Olivares, J., Turner, S. (2008). Brief form of the Social Phobia and Anxiety Inventory (SPAI-B) for
adolescents. European Journal of Psychological Assessment, 24, 150-156. doi: 10.1027/1015-5759.24.3.150.
García-López, L. J., Olivares, J., & Hidalgo, M. D. (2005). A pilot study on sensitivity of outcome measures for treatments of generalized social phobia in Spanish
adolescents. International Journal of Clinical and Health Psychology, 5, 385-392. doi: 1697-2600.
Gómez-Ariza, C. J., Iglesias-Parro, S., Garcia-López, L. J., Díaz-Castela, M. M.,
Espinosa-Fernández, L., & Muela, J. A. (2013). Selective intentional forgetting in adolescents with social anxiety disorder. Psychiatry Research, 208, 151-155. doi: 10.1016/j.psychres.2012.09.027.
Hamilton, J. P., Chen, M. C., Waugh, C. E., Joormann, J., & Gotlib, I. H. (2014). Distinctive and common neural underpinnings of major depression, social anxiety, and their comorbidity. Social Cognitive and Affective Neuroscience,
electronic publication. doi: 10.1093/scan/nsu084.
Heimberg, R. G., Hofmann, S. G., Liebowitz, M. R., Schneier, F. R., Smits, J. A. J., Stein, M. B., Hinton, D. E., & Craske, M. G. (2014). Social anxiety disorder in DSM-5. Depression and Anxiety, 00, 1-8. doi: 10.1002/da.22231.
Hofmann, W., Schmeichel, B. J., & Baddeley, A. D. (2012). Executive functions and self-regulation. Trends in Cognitive Sciences, 16, 174-180. doi:
10.1016/j.tics.2012.01.006.
Lavie, N., Hirst, A., de Fockert, J. W., & Viding, E. (2004). Load theory of selective attention and cognitive control. Journal of Experimental Psychology, 133, 339-354. doi: 10.1037/0096-3445.133.3.339.
Leary, M. R. (1983). A brief version of the fear of negative evaluation scale.
Personality and Social Psychology Bulletin, 9, 371-375. doi:
Lustig, C., May, C. P., & Hasher, L. (2001). Working memory span and the role of proactive interference. Journal of Experimental Psychology, 130, 199-207. doi: 10.1037/0096-3445.130.2.199.
Mednick, S. A. (1962). The associative basis of the creative process. Psychological
Review, 69, 220-232. doi: 10.1037/h0048850.
Miyake, A., Friedman, N. P., Emerson, M. J., Witzki, A. H., & Howerter, A. (2000). The unity and diversity of executive functions and their contributions to complex “frontal lobe” tasks: A latent variable analysis. Cognitive Psychology,
41, 49-100. doi: 10.1006/cogp.1999.0734.
Moriya, J., & Sugiura, Y. (2012). Impaired attentional disengagement from stimuli matching the contents of working memory in social anxiety. PLOS one, 7, 1-8. doi: 10.1371/journal.pone.0047221.
Moscovitch, D. A., Rodebaugh, T. L., & Hesch, B. D. (2011). How awkward! Social anxiety and the perceived consequences of social blunders. Behaviour
Research and Therapy, 50, 142-149. doi: 10.1016/j.brat.2011.11.002.
Ortega, A., Gómez-Ariza, C. J., Román, P., & Bajo, M. T. (2012). Memory inhibition, aging, and the executive deficit hypothesis. Journal of Experimental
Psychology: Learning, Memory, and Cognition. Online publication. doi:
10.1037/a0024510.
Pimperton, H., & Nation, K. (2010). Suppressing irrelevant information from working memory: Evidence for domain-specific deficits in poor
comprehenders. Journal of Memory and Language, 62, 380-391. doi: 10.1016/j.jml.2010.02.005.
Piqueras, J. A., Espinosa-Fernández, L., Garcia-Lopez, L. J., & Biedel, D. C. (2012). Validación del “Inventario de Ansiedad y Fobia Social-Forma Breve” (SPAI-B) en jóvenes adultos españoles. Psicología Conductal, 20, 505-528.
Perfect, T. J., Moulin, C. J. A., Conway, M. A., & Perry, E. (2002). Assessing the inhibitory account of retrieval-induced forgetting with implicit-memory tests.
Journal of Experimental Psychology: Learning, Memory, and Cognition, 28,
1111-1119. doi: 10.1037/0278-7393.28.6.1111
Rachmann, S., Grüter-Andrew, J., & Shafran, R. (2000). Post-event processing in social anxiety. Behavioural Research and Therapy, 38, 611-617. doi: 10.1016/S0005-7967(99)00089-3.
Rapee, R. M., & Heimberg, R. G. (1997). A cognitive-behavioral model of anxiety in social phobia. Behaviour Research and Therapy, 35, 741-756. doi: 9256517.
Rodebaugh, T. L., Woods, C. M., Thissen, D. M., Heimberg, R. G., Chambless, D. L., & Rapee, R. M. (2004). More information from fewer questions: The factor structure and item properties of the original and Brief Fear of Negative Evaluation Scale. Psychological Assessment, 16, 169-181. doi: 10.1037/1040-3590.16.2.169.
Sanz, J., Perdigón, A. L., & Vázquez, C. (2003). The Spanish adaptation of Beck’s Depression Inventory-II (BDI-II): 2. Psychometric properties in the general population. Clínica y Salud, 14, 249-280.
Schmidt, N. B., Richey, J. A., Buckner, J. D., & Timpano, K. R. (2009). Attention training for generalized social anxiety disorder. Journal of Abnormal
Smith, S. M. (2003). The constraining effects of initial ideas. In P. Paulus & B. Nijstad (Eds.), Group creativity: Innovation through collaboration (pp. 15-31). Oxford, England: Oxford University Press.
Stopa, L., & Clark, D. M. (2000). Social phobia and interpretation of social events.
Behaviour Research and Therapy, 38, 273-283. doi:
10.1016/S0005-7967(99)00043-1.
Storm, B. C., & Angello, G. (2010). Overcoming fixation: Creative problem solving and retrieval-induced forgetting. Psychological Science, 21, 1263-1265. doi: 10.1177/0956797610379864.
Storm, B. C., & Levy, B. J. (2012). A progress report on the inhibitory account of retrieval-induced forgetting. Memory and Cognition, 40, 827-843. doi: 10.3758/s13421-012-0211-7
Turner, S. M., Stanley, M. A., Beidel, D. C., & Bond, L. (1989). The social phobia and anxiety inventory. Construct validity. Journal of Psychopathology and
Behavioral Assessment, 11, 221-234.
Valiente, R. M., Chorot, P., & Sandín, B. (2003). Entrevista para el diagnóstico de
los trastornos de ansiedad. Madrid: Klinik.
Voncken, M. J., Bögels, S. M., & de Vries, K. (2003). Interpretation and judgmental biases in social phobia. Behaviour Research and Therapy, 41, 1481-1488. doi: 10.1016/S0005-7967(03)00143-8.
Weiss, B. J., Hope, D. A., & Capozzoli, M. C. (2013). Heterocentric language in
commonly used measures of social anxiety: Recommended alternate wording.
