Memory for affectively valenced and neutral stimuli in depression: Evidence from a novel matching task

Depressed persons have better memory for affectively negative than positive stimuli, a pattern generally not exhibited by non-depressed individuals. The mechanisms underlying this differential memory are not clear. In this study we examined memory for valenced and neutral stimuli in depressed and non-depressed individuals under conditions of relatively unconstrained encoding. We developed a novel task based on the game, Concentration, in which participants tried to match pairs of positive and negative words, and pairs of neutral words, hidden under squares in as few turns as possible. Whereas non-depressed participants selected and turned over positive squares more frequently than they did negative squares, depressed participants selected and turned over positive and negative squares equally often. Depressed participants also matched fewer positive word pairs within the first five minutes of the task than did non-depressed participants, and they exhibited poorer learning of positive words. Depressed and non-depressed participants did not differ in their matching of neutral words. These findings add to a growing literature indicating that depression is characterised by difficulties in the processing of positive stimuli.     

Biases in Visual Attention in Depressed and Nondepressed Individuals

Abstract

The present study utilised a cognitive paradigm to examine attentional biases in mildly depressed persons. Twelve depressed and 12 nondepressed subjects completed an attentional task similar to that employed by MacLeod, Mathews, and Tata (1986). A tachistiscope was used to present subjects with a series of word pairs, each with one word printed above the other. Three types of word pairs were presented: manic-neutral, depressed-neutral, and manic-depressed. Selective attention to one member of a word pair was assessed using ac perception task. Based on cognitive models of depression, it was hypothesised that the depressed subjects would attend more to depressed-content words than to manic- or neutral-content words, whereas the nondepressed subjects would not exhibit any attentional biases. In contrast to these predictions, analyses indicated that whereas the depressed subjects attended equally to depressed-, manic-, and neutral-content words, the nondepressed subjects attended more to manic-content than they did to neutral- or depressed-content words. These results add support to the documentation of evenhandedness in the cognitive functioning of depressed subjects, and of self-sewing biases in nondepressed subjects. The present findings are discussed in terms of a zoom lens model of attention, in which depressed persons attempt to exhaustively process their sensory world, but with a loss of attentional resolution. In contrast, nondepressed individuals attempt to process a more limited portion of their sensory world, but with an increase in attentional power. Finally, directions for future research in this area are offered.     

Remembering the good, forgetting the bad: intentional forgetting of emotional material in depression

The authors examined intentional forgetting of negative material in depression. Participants were instructed to not think about emotional nouns that they had learned to associate with a neutral cue word. The authors provided participants with multiple occasions to suppress the unwanted words. Overall, depressed participants successfully forgot negative words. Moreover, the authors obtained a clear practice effect. However, forgetting came at a cost: Compared with the nondepressed participants and with the depressed participants who were instructed to forget positive words, depressed participants who were instructed to forget negative words showed significantly worse recall of the baseline words. These results indicate that training depressed individuals in intentional forgetting could prove to be an effective strategy to counteract automatic ruminative tendencies and mood-congruent biases.     

Interpretation Bias Training in Depressed Adolescents: Near- and Far-Transfer Effects

Depressed adolescents are characterized by negative interpretation biases. Although investigators have used cognitive bias modification for interpretation (CBM-I) to experimentally manipulate interpretation biases in depressed adults, the near- and far-transfer effects are not well understood in adolescents diagnosed with Major Depressive Disorder (MDD). In this study, we extend previous research by investigating the near- and far-transfer effects of 6 sessions of Positive versus Neutral CBM-I on independent measures of interpretation bias (near-transfer effects) and on attention biases and clinical symptoms (far-transfer effects) in a sample of adolescents with MDD (n = 46). At post-training, adolescents who received Positive CBM-I interpreted ambiguous scenarios more positively than did participants who received Neutral CBM-I, providing evidence of training effectiveness. There was no evidence, however, of near- or far-transfer effects. These findings raise concerns about the malleability of interpretation biases in adolescent depression and suggest that further work is needed to establish the clinical utility of CBM-I for adolescents with MDD.     

Memory for affectively valenced and neutral stimuli in depression: evidence from a novel matching task

Depressed persons have better memory for affectively negative than positive stimuli, a pattern generally not exhibited by non-depressed individuals. The mechanisms underlying this differential memory are not clear. In this study we examined memory for valenced and neutral stimuli in depressed and non-depressed individuals under conditions of relatively unconstrained encoding. We developed a novel task based on the game, Concentration, in which participants tried to match pairs of positive and negative words, and pairs of neutral words, hidden under squares in as few turns as possible. Whereas non-depressed participants selected and turned over positive squares more frequently than they did negative squares, depressed participants selected and turned over positive and negative squares equally often. Depressed participants also matched fewer positive word pairs within the first five minutes of the task than did non-depressed participants, and they exhibited poorer learning of positive words. Depressed and non-depressed participants did not differ in their matching of neutral words. These findings add to a growing literature indicating that depression is characterised by difficulties in the processing of positive stimuli.     

Self-referential schemas and attentional bias predict severity and naturalistic course of depression symptoms

Attentional bias and self-referential schemas have been observed in numerous cross-sectional studies of depressed adults and are theorised to maintain negative mood. However, few longitudinal studies have examined whether maladaptive cognition predicts the course of depressive symptoms. Fifty-seven adults with elevated depression symptoms were assessed for negative attentional bias using a dot-probe task with eye-tracking and self-referential schemas using a self-referent encoding task. Participants subsequently completed five weekly depression symptom assessments. Participants with more negative self-referential schemas had higher baseline depression symptoms (r?=?.55). However, participants who spent more time attending to negative words showed greater symptom worsening over time (r?=?.42). The findings for negative self-referential schemas replicate past research, while the findings for negative attention bias represent the first evidence showing that attentional biases predict naturalistic symptom course. This work suggests that negative attention biases maintain depression symptoms and represent an important treatment target for neurocognitive therapeutics.     

Affective valence and memory in depression: dissociation of recall and fragment completion.

Depressed (n = 16) and nondepressed (n = 16) subjects' memory for affectively valenced words was assessed by an explicit test (free recall) and an implicit test (word fragment completion). Under free-recall instructions, depressed subjects recalled significantly more negatively valenced than positively valenced words, whereas the opposite pattern was observed in nondepressed control subjects. These results replicate those previously reported in the literature. The differential effect of word valence was absent, however, when memory was tested implicitly: Depressed and nondepressed subjects exhibited equivalent priming of positive and negative words. These data are discussed in terms of Williams, Watts, MacLeod, and Mathews's (1988) model of depression.     

A comparison of attentional biases and memory biases in women with social phobia and major depression

Cognitive processes play an important role in the etiology and maintenance of anxiety and depression. Current theories differ, however, in their predictions regarding the occurrence of attentional biases and memory biases in depression and anxiety. To allow for a systematic comparison of disorders and cognitive processes, 117 women (35 with generalized social phobia, 27 with major depression, and 55 healthy controls) participated in a test of visual attention (visual search), an explicit memory test (free recall), and an implicit memory test (anagram solving). Both clinical groups exhibited attentional biases for disorder-related words, whereas only depressed participants showed clear evidence of explicit and implicit memory biases. The implications of these results for competing theories are discussed.     

Neurophysiological indices of free recall memory biases in major depression: The impact of stimulus arousal and valence

This study examined differential impact of the valence and arousal characteristics of stimuli on memory biases and brain activity in major depressive disorder (MDD) and non-depressed control participants. P300 and slow wave (SW) components of the event-related brain potential (ERP) were recorded in 18 MDD and 18 control individuals during the encoding of positive and negative, high and low arousal words in a free recall task. Control participants demonstrated expected enhanced memory for positive stimuli that was accompanied by a corresponding increase in SW ERP components. These effects were not seen in the MDD participants. Rather, memory biases for negative information in MDD were only observed for low arousal words and were not reflected in ERP amplitudes. This study suggests that the inconsistency in the MDD memory bias literature may be related to the arousing nature of the stimuli incorporated in the study.     

Depth of processing and recall of threat material in fearful and nonfearful individuals

Abstract

Although many studies have examined the nature of memory distortions in anxious individuals, few have considered biases in specific memory processes, such as encoding or retrieval. To investigate whether the presentation of threat material facilitates encoding biases, spider fearful (n=63), blood fearful (n=73), and nonfearful (n=75) participants encoded spider related, blood related, and neutral words as a function of three levels of processing (i.e., structural, semantic, and self referent). Participants subsequently completed either a free recall or a recognition task. All participants demonstrated a partial depth of processing effect, such that they recalled more words encoded in the self referent condition than in the other two conditions, but groups did not differ in their recall of stimuli as a function of word type. Relative to participants in the other groups, spider fearful participants had fewer spider related intrusions in the recall condition, and they made fewer errors in responding to structural and semantic encoding questions when spider related words were presented. These results contribute to an increasingly large body of literature suggesting that anxious individuals are not characterized by a memory bias toward threat, and they raise the possibility that individuals with spider fears process threat-relevant information differently than individuals with blood fears.     

Updating the contents of working memory in depression: interference from irrelevant negative material

This study was designed to assess the effects of irrelevant emotional material on the ability to update the contents of working memory in depression. For each trial, participants were required to memorize 2 lists of emotional words and subsequently to ignore 1 of the lists. The impact of irrelevant emotional material on the ability to update the contents of working memory was indexed by response latencies on a recognition task in which the participants decided whether or not a probe was a member of the relevant list. The authors compared response latencies to probes from the irrelevant list to response latencies to novel probes of the same valence (intrusion effect). The results indicate that, compared to control participants in both neutral and sad mood states, depressed participants showed greater intrusion effects when presented with negative words. In an important finding, intrusion effects for negative words were correlated with self-reported rumination. These findings indicate that depression is associated with difficulties removing irrelevant negative material from working memory. Results also indicate that the increased interference from irrelevant negative material is associated with rumination.     

Depression reduces perceptual sensitivity for positive words and pictures

There is evidence of maladaptive attentional biases for lexical information (e.g., Atchley, Ilardi, & Enloe, 2003; Atchley, Stringer, Mathias, Ilardi, & Minatrea, 2007) and for pictographic stimuli (e.g., Gotlib, Krasnoperova, Yue, & Joormann, 2004) among patients with depression. The current research looks for depressotypic processing biases among depressed out-patients and non-clinical controls, using both verbal and pictorial stimuli. A d′ measure (sensitivity index) was used to examine each participant's perceptual sensitivity threshold. Never-depressed controls evidenced a detection bias for positive picture stimuli, while depressed participants had no such bias. With verbal stimuli, depressed individuals showed specific decrements in the detection of positive person-referent words (WINNER), but not with positive non-person-referent words (SUNSHINE) or with negative words. Never-depressed participants showed no such differences across word types. In the current study, depression is characterised both by an absence of the normal positivistic biases seen in individuals without mood disorders (consistent with McCabe & Gotlib, 1995), and by a specific reduction in sensitivity for person-referent positive information that might be inconsistent with depressotypic self-schemas.     

Cognitive and neural consequences of memory suppression in major depressive disorder

Negative biases in cognition have been documented consistently in major depressive disorder (MDD), including difficulties in the ability to control the processing of negative material. Although negative information-processing biases have been studied using both behavioral and neuroimaging paradigms, relatively little research has been conducted examining the difficulties of depressed persons with inhibiting the retrieval of negative information from long-term memory. In this study, we used the think/no-think paradigm and functional magnetic resonance imaging to assess the cognitive and neural consequences of memory suppression in individuals diagnosed with depression and in healthy controls. The participants showed typical behavioral forgetting effects, but contrary to our hypotheses, there were no differences between the depressed and nondepressed participants or between neutral and negative memories. Relative to controls, depressed individuals exhibited greater activity in right middle frontal gyrus during memory suppression, regardless of the valence of the suppressed stimuli, and differential activity in the amygdala and hippocampus during memory suppression involving negatively valenced stimuli. These findings indicate that depressed individuals are characterized by neural anomalies during the suppression of long-term memories, increasing our understanding of the brain bases of negative cognitive biases in MDD.     

Recollective Experience During Recognition of Emotional Words in Clinical Depression

Earlier work has shown that free recall tasks produce a robust mood-congruent memory effect in depression, whereas recognition tasks produce heterogeneous results. This study aimed to further investigate recognition memory for positive, negative and neutral words in depressed patients and matched comparison participants with the Remember/Know/Guess procedure for assessing recollection and familiarity. No mood-congruent memory bias effect was detected in discrimination abilities. However, depressed patients recollected (more Remember responses) more negative than positive or neutral words, whereas comparison participants recollected more positive than neutral words. No mood-congruent pattern was evidenced for Know responses. However, the depressed patients responded to fewer words overall with Know responses than the comparison participants. These results suggest that the mood-congruent memory pattern in depressed patients is related to conscious recollection rather than to familiarity. Attentional biases toward negative words and elaboration processes and/or encoding in reference to the self may contribute to these findings.     

Investigating the role of attentional resources in the irrelevant speech effect

Irrelevant words can be disruptive to performance, and the frequency of usage of the irrelevant words has affected the magnitude of such disruption (Buchner &; Erdfelder, 2005). The finding of word frequency differences in the magnitude of the irrelevant speech effect (ISE) implicated a role for attentional processes. Using a different conceptualization of attention, researchers have found that individual differences in working memory capacity did not predict the magnitude of the ISE, which questioned the role of attentional control (Beaman, 2004; Sörqvist, 2010). The current study investigated aspects of the construct of attention and the ISE, using both individual and developmental difference approaches. Results showed no significant difference between serial recall performances in the presence of high or low word frequency distractors. Furthermore, effects of working memory capacity differences were not found, but children displayed a larger ISE than college students. The weight of the evidence appears against an attentional resource view of the ISE.     

Cognitive processing of emotional information in depression, panic, and somatoform disorder

Emotional Stroop tasks (subliminal/supraliminal exposures), implicit memory tasks (tachistoscopic word identification), and explicit memory tasks (free recall after incidental learning) with 4 word types (physical threat, positive, negative, and neutral words) were administered to patients with major depressive disorder (n=30), panic disorder (n=33), somatoform disorder (n=25), and healthy control participants (n=33). On the Stroop task, panic patients showed subliminal interferences for physical threat and negative words, depressive patients showed supraliminal interferences for negative words, and somatoform patients showed supraliminal interferences for physical threat words. No patient groups demonstrated implicit memory biases. On the explicit memory task, depressive and panic patients showed memory biases for negative words; somatoform patients showed biases for physical threat words.     

Attention and memory biases for aggressive information in college students with fragile high self-esteem

In this study, we examined attention and memory biases for aggressive information in two groups of college students. Individuals with fragile high self-esteem (n = 30) and individuals with secure high self-esteem (n = 30) first performed a dot-probe task investigating attention bias, followed by a memory task. Incidental free recall of words presented in the memory task was then completed to assess memory bias. Results revealed that individuals with fragile high self-esteem exhibited significant attention and memory biases for aggressive words compared with secure high self-esteem individuals. Attention bias for aggressive words was positively correlated with memory bias in individuals with fragile high self-esteem, but no correlation was found for individuals with secure high self-esteem. These findings suggest that individuals with fragile high self-esteem selectively attend to and remember aggression-related information. They may process information in ways that are congruent with an aggression-related schema. This study reveals the aggressive cognitive processes of individuals with fragile high self-esteem, which may be related to aggression.     

Mood-congruent attention and memory bias in dysphoria: Exploring the coherence among information-processing biases

Recent studies indicate that depression is characterized by mood-congruent attention bias at later stages of information-processing. Moreover, depression has been associated with enhanced recall of negative information. The present study tested the coherence between attention and memory bias in dysphoria. Stable dysphoric (n = 41) and non-dysphoric (n = 41) undergraduates first performed a spatial cueing task that included negative, positive, and neutral words. Words were presented for 250 ms under conditions that allowed or prevented elaborate processing. Memory for the words presented in the cueing task was tested using incidental free recall. Dysphoric individuals exhibited an attention bias for negative words in the condition that allowed elaborate processing, with the attention bias for negative words predicting free recall of negative words. Results demonstrate the coherence of attention and memory bias in dysphoric individuals and provide suggestions on the influence of attention bias on further processing of negative material.     

Interference resolution in major depression

In two experiments, we investigated individual differences in the ability to resolve interference in participants diagnosed with major depressive disorder (MDD). Participants were administered the “Ignore/Suppress” task, a short-term memory task composed of two steps. In Step 1 (“ignore”), participants were instructed to memorize a set of stimuli while ignoring simultaneously presented irrelevant material. In Step 2 (“suppress”), participants were instructed to forget a subset of the previously memorized material. The ability to resolve interference was indexed by response latencies on two recognition tasks in which participants decided whether a probe was a member of the target set. In Step 1, we compared response latencies to probes from the to-be-ignored list with response latencies to nonrecently presented items. In Step 2, we compared response latencies to probes from the to-be-suppressed list with response latencies to nonrecently presented items. The results indicate that, compared with control participants, depressed participants exhibited increased interference in the “suppress” but not in the “ignore” step of the task, when the stimuli were negative words. No group differences were obtained when we presented letters instead of emotional words. These findings indicate that depression is associated with difficulty in removing irrelevant negative material from short-term memory.