Do emotional stimuli enhance or impede recall relative to neutral stimuli? An investigation of two “false memory” tasks

Many eyewitness memory situations involve negative and distressing events; however, many studies investigating “false memory” phenomena use neutral stimuli only. The aim of the present study was to determine how both the Deese–Roediger–McDermott (DRM) procedure and the Misinformation Effect Paradigm tasks were related to each other using distressing and neutral stimuli. Participants completed the DRM (with negative and neutral word lists) and viewed a distressing or neutral film. Misinformation for the film was introduced and memory was assessed. Film accuracy and misinformation susceptibility were found to be greater for those who viewed the distressing film relative to the neutral film. Accuracy responses on both tasks were related, however, susceptibility to the DRM illusion and Misinformation Effect were not. The misinformation findings support the Paradoxical Negative Emotion (PNE) hypothesis that negative stimuli will lead to remembering more accurate details but also greater likelihood of memory distortion. However, the PNE hypothesis was not supported for the DRM results. The findings also suggest that the DRM and Misinformation tasks are not equivalent and may have differences in underlying mechanisms. Future research should focus on more ecologically valid methods of assessing false memory.     

Enhanced perceptual priming for neutral stimuli in a traumatic context: A pathway to intrusive memories?

Clinical observations suggest that re-experiencing symptoms are triggered by stimuli that are perceptually similar to those present shortly before the trauma or its worst moments. Two experiments investigated the possible role of perceptual priming in this phenomenon. Volunteers (N = 28, N = 62) watched a series of "traumatic" and neutral picture stories, and completed blurred object identification (priming) and recognition memory tasks. Neutral objects that immediately preceded the "traumatic" stories were more strongly primed, but not better recognised, than objects from neutral stories. Enhanced priming predicted subsequent re-experiencing symptoms. The results support the role of perceptual priming in re-experiencing.     

Enhanced perceptual priming for neutral stimuli in a traumatic context: A pathway to intrusive memories?

Clinical observations suggest that re-experiencing symptoms are triggered by stimuli that are perceptually similar to those present shortly before the trauma or its worst moments. Two experiments investigated the possible role of perceptual priming in this phenomenon. Volunteers (N = 28, N = 62) watched a series of “traumatic” and neutral picture stories, and completed blurred object identification (priming) and recognition memory tasks. Neutral objects that immediately preceded the “traumatic” stories were more strongly primed, but not better recognised, than objects from neutral stories. Enhanced priming predicted subsequent re-experiencing symptoms. The results support the role of perceptual priming in re-experiencing.     

Time-course of attention to negative stimuli: Negative affectivity, anxiety, or dysphoria?

Although biased attention to emotional stimuli is considered a vulnerability factor for anxiety and dysphoria, research has infrequently related such attentional biases to dimensional models of vulnerability for anxiety and mood disorders. In two studies (Study 1, n = 64; Study 2, n = 168), we evaluate the differential associations of general negative affectivity, anxiety, and dysphoria with biases in selective attention among nonclinical participants selected to vary in both anxiety and dysphoria. Across both studies, preferential processing of angry faces at a 300-ms exposure duration was associated with a general tendency to experience a range of negative affect, rather than being specific to symptoms of either anxiety or dysphoria. In the second study, we found evidence of a suppressor relationship between anxiety and dysphoria in the prediction of delayed attentional biases (1,000 ms) for sad faces. In particular, dysphoria was specifically associated with biased attention toward sad cues, but only after statistically accounting for anxiety; by contrast, anxiety was specifically associated with attentional avoidance of sad cues, but only after statistically accounting for dysphoria. These results suggest that the specificity of relationships between components of negative affectivity and attention to emotional stimuli varies as a function of the time course at which attentional biases are assessed, highlighting the importance of evaluating both anxiety and dysphoria in research on attentional processing of emotional stimuli. (PsycINFO Database Record (c) 2012 APA, all rights reserved).     

How many pixels make a memory? Picture memory for small pictures

Torralba (Visual Neuroscience, 26, 123–131, 2009) showed that, if the resolution of images of scenes were reduced to the information present in very small “thumbnail images,” those scenes could still be recognized. The objects in those degraded scenes could be identified, even though it would be impossible to identify them if they were removed from the scene context. Can tiny and/or degraded scenes be remembered, or are they like brief presentations, identified but not remembered. We report that memory for tiny and degraded scenes parallels the recognizability of those scenes. You can remember a scene to approximately the degree to which you can classify it. Interestingly, there is a striking asymmetry in memory when scenes are not the same size on their initial appearance and subsequent test. Memory for a large, full-resolution stimulus can be tested with a small, degraded stimulus. However, memory for a small stimulus is not retrieved when it is tested with a large stimulus.     

The dot-probe task to measure emotional attention: A suitable measure in comparative studies?

For social animals, attending to and recognizing the emotional expressions of other individuals is of crucial importance for their survival and likely has a deep evolutionary origin. Gaining insight into how emotional expressions evolved as adaptations over the course of evolution can be achieved by making direct cross-species comparisons. To that extent, experimental paradigms that are suitable for investigating emotional processing across species need to be developed and evaluated. The emotional dot-probe task, which measures attention allocation toward emotional stimuli, has this potential. The task is implicit, and subjects need minimal training to perform the task successfully. Findings in nonhuman primates, although scarce, show that they, like humans, have an attentional bias toward emotional stimuli. However, the wide literature on human studies has shown that different factors can have important moderating effects on the results. Due to the large heterogeneity of this literature, these moderating effects often remain unnoticed. We here review this literature and show that subject characteristics and differences in experimental designs affect the results of the dot-probe task. We conclude with specific recommendations regarding these issues that are particularly relevant to take into consideration when applying this paradigm to study animals.     

Adaptive memory: Is the animacy effect on memory due to emotional arousal?

Animate entities are often better remembered than inanimate ones. The proximal mechanisms underlying this animacy effect on recall are unclear. In two experiments, we tested whether the animacy effect is due to emotional arousal. Experiment 1 revealed that translations of the animate words used in the pioneering study of Nairne et al. (Psychological science, 24, 2099–2105, 2013) were perceived as being more arousing than translations of the inanimate words, suggesting that animacy might have been confounded with arousal in previous studies. In Experiment 2, new word lists were created in which the animate and inanimate words were matched on arousal (amongst several other dimensions), and participants were required to reproduce the animate and inanimate words in a free recall task. There was a tendency towards better memory for arousing items, but robust animacy effects were obtained even though animate and inanimate words were matched on arousal. Thus, while arousal may contribute to the animacy effect when it is not carefully controlled for, it cannot explain the memory advantage of animate items.     

Is there an advantage for recognizing multi-modal emotional stimuli?

Emotions can be recognized whether conveyed by facial expressions, linguistic cues (semantics), or prosody (voice tone). However, few studies have empirically documented the extent to which multi-modal emotion perception differs from uni-modal emotion perception. Here, we tested whether emotion recognition is more accurate for multi-modal stimuli by presenting stimuli with different combinations of facial, semantic, and prosodic cues. Participants judged the emotion conveyed by short utterances in six channel conditions. Results indicated that emotion recognition is significantly better in response to multi-modal versus uni-modal stimuli. When stimuli contained only one emotional channel, recognition tended to be higher in the visual modality (i.e., facial expressions, semantic information conveyed by text) than in the auditory modality (prosody), although this pattern was not uniform across emotion categories. The advantage for multi-modal recognition may reflect the automatic integration of congruent emotional information across channels which enhances the accessibility of emotion-related knowledge in memory.     

Can attention give a left-ear advantage for verbal stimuli?

Three independent groups of 8 subjects listened monaurally to a randomized list of 50 common and 50 rare words and responded ‘yes’ to rare words. Responses were analyzed for correct identifications of rare words. A 50:50 group heard an equal number of words in right and left ears and gave a small but non-significant right-ear superiority. A 66:34 group heard nearly twice as many words in the right ear as the left and gave a significant right-ear superiority. A 34:66 group heard nearly twice as many words in the left ear as the right and gave a significant left-ear superiority. Responses were also analyzed according to signal-detection theory. Implications are discussed for theories of ear advantages.     

Attention for emotional faces under restricted awareness revisited: do emotional faces automatically attract attention?

Theoretical models of attention for affective information have assigned a special status to the cognitive processing of emotional facial expressions. One specific claim in this regard is that emotional faces automatically attract visual attention. In three experiments, the authors investigated attentional cueing by angry, happy, and neutral facial expressions that were presented under conditions of limited awareness. In these experiments, facial expressions were presented in a masked (14 ms or 34 ms, masked by a neutral face) and unmasked fashion (34 ms or 100 ms). Compared with trials containing neutral cues, delayed responding was found on trials with emotional cues in the unmasked, 100-ms condition, suggesting stronger allocation of cognitive resources to emotional faces. However, in both masked and unmasked conditions, the hypothesized cueing of visual attention to the location of emotional facial expression was not found. In contrary, attentional cueing by emotional faces was less strong compared with neutral faces in the unmasked, 100-ms condition. These data suggest that briefly presented emotional faces influence cognitive processing but do not automatically capture visual attention.     

Can semantic relatedness explain the enhancement of memory for emotional words?

Memory for emotional items is often better than memory for neutral items. In three experiments, we examined whether this typical finding is due to the higher semantic relatedness inherent to emotional items, a confound in previous studies. We also controlled for other possible confounding variables, such as imagery. In Experiments 1 and 2, participants encoded lists of emotional and categorized neutral words equivalent in semantic relatedness, as well as lists of random neutral words with lower semantic relatedness. In Experiment 3, the lists were mixed, containing words from all the conditions. Surprise free recall was tested after a 40- to 55-min retention interval. Free recall of emotional words was better than that of random neutral words, replicating the classic effect. Importantly, categorized words were recalled better than random neutral words, and not worse than emotional words. These results emphasize the important role of semantic relatedness in the classic effect and suggest that organizational processes operate alongside arousal-related ones to enhance memory for emotional material.     

Bulimics' responses to food cravings: is binge-eating a product of hunger or emotional state?

This study examined the roles of hunger, food craving and mood in the binge-eating episodes of bulimic patients, and identified the critical factors involved in the processes surrounding binge-eating episodes that follow cravings. This was a prospective study of the binge-eating behaviour of 15 women with bulimia nervosa. The participants used food intake diaries and Craving Records to self-monitor their nutritional behaviour, hunger levels and affective state. Cravings leading to a binge were associated with higher tension, lower mood and lower hunger than those cravings not leading to a binge. Levels of tension and hunger were the critical discriminating variables. The findings of the study support empirical evidence and models of emotional blocking in binge-eating behaviour and challenge the current cognitive starve-binge models of bulimia. The role of food cravings in the emotional blocking model is discussed in terms of a classically conditioned motivational state. Implications for treatment are addressed.     

Attentional interference effects of emotional pictures: threat, negativity, or arousal?

Attentional interference arising from emotional pictures was examined. Participants had to ignore emotional pictures while solving math problems (Study 1, N = 126) or detecting the location of a line (Study 2, N = 60). Data analyses tested predictions of 3 theories. Evolutionary threat theory predicts interference by snake pictures. Categorical negativity theory predicts interference by negative pictures regardless of their intensity. According to arousal theory, arousal level predicts interference effects. The results supported arousal theory, with the most arousing pictures (strong unpleasant pictures, oppositesex models) producing the strongest interference. The findings are interpreted in the context of process models of emotions that postulate an initial relevance check before further processing of valence and other appraisal dimensions.     

Listening back in time: Does attention to memory facilitate word-in-noise identification?

The ephemeral nature of spoken words creates a challenge for oral communications where incoming speech sounds must be processed in relation to representations of just-perceived sounds stored in short-term memory. This can be particularly taxing in noisy environments where perception of speech is often impaired or initially incorrect. Usage of prior contextual information (e.g., a semantically related word) has been shown to improve speech in noise identification. In three experiments, we demonstrate a comparable effect of a semantically related cue word placed after an energetically masked target word in improving accuracy of target-word identification. This effect persisted irrespective of cue modality (visual or auditory cue word) and, in the case of cues after the target, lasted even when the cue word was presented up to 4 seconds after the target. The results are framed in the context of an attention to memory model that seeks to explain the cognitive and neural mechanisms behind processing of items in auditory memory.     

Reconsolidation from negative emotional pictures: Is successful retrieval required?

Finn and Roediger (Psychological Science 22:781-786, 2011) found that when a negative emotional picture was presented immediately after a successful retrieval, later test performance was enhanced as compared to when a neutral picture or a blank screen had been shown. This finding implicates the period immediately following retrieval as playing an important role in determining later retention via reconsolidation. In two new experiments, we investigated whether successful retrieval was required to show the enhancing effect of negative emotion on later recall. In both experiments, the participants studied Swahili-English vocabulary pairs, took an intervening cued-recall test, and were given a final cued-recall test on all items. In Experiment 1, we tested a distinctiveness explanation of the effect. The results showed that neither presentation of a negative picture just prior to successful retrieval nor presentation of a positive picture after successful retrieval produced the enhancing effect that was seen when negative pictures were presented after successful retrieval. In Experiment 2, we tested whether the enhancing effect would occur when a negative picture followed an unsuccessful retrieval attempt with feedback, and a larger enhancement effect occurred after errors of commission than after errors of omission. These results indicate that effort in retrieving is critical to the enhancing effect shown with negative pictures; whether the target is produced by the participant or given by an external source following a commission error does not matter. We interpret these results as support for semantic enrichment as a key element in producing the enhancing effect of negative pictures that are presented after a retrieval attempt.     

Influence of facial expression on memory for facial identity: effects of visual features or emotional meaning?

Research has shown that neutral faces are better recognized when they had been presented with happy rather than angry expressions at study, suggesting that emotional signals conveyed by facial expressions influenced the encoding of novel facial identities in memory. An alternative explanation, however, would be that the influence of facial expression resulted from differences in the visual features of the expressions employed. In this study, this possibility was tested by manipulating facial expression at study versus test. In line with earlier studies, we found that neutral faces were better recognized when they had been previously encountered with happy rather than angry expressions. On the other hand, when neutral faces were presented at study and participants were later asked to recognize happy or angry faces of the same individuals, no influence of facial expression was detected. As the two experimental conditions involved exactly the same amount of changes in the visual features of the stimuli between study and test, the results cannot be simply explained by differences in the visual properties of different facial expressions and may instead reside in their specific emotional meaning. The findings further suggest that the influence of facial expression is due to disruptive effects of angry expressions rather than facilitative effects of happy expressions. This study thus provides additional evidence that facial identity and facial expression are not processed completely independently.     

Switching between memory and perception: Moving attention or memory retrieval?

Weber, Burt, and Noll (1986) estimated that the time needed to switch attention between memory and perception was around 300 msec. The first two experiments in the present paper estimated switching time using a variation of their task. Subjects reported aloud lists of six items. The items were read off a computer screen (perception), recited from memory, or reported alternately from the two sources. The data show that the switching-time estimate is influenced by input/output compatibility, response-initiation times, and memory load. When these factors were controlled, estimated switching time dropped to around 100-150 msec. The data suggest, however, that the switch from perception to memory might be slower than the switch from memory to perception, which would invalidate the formula used to compute switching time. Experiment 3 tested the time for a single switch from perception to memory and a single switch from memory to perception by restricting report to one pair of items in the list. When the to-be-reported pair was precued, estimated switching time dropped to zero. When the pair was not precued, the memory-to-perception switching time remained at zero, but the perception-to-memory time was more than 400 msec. The pattern of results forced a reconceptualization of the task in terms of memory retrieval rather than attention switching. The attention-switching times appear to reflect processes required to select items from memory.     

Multiple-target tracking: A role for working memory?

In order to identify the cognitive processes associated with target tracking, a dual-task experiment was carried out in which participants undertook a dynamic multiple-object tracking task first alone and then again, concurrently with one of several secondary tasks, in order to investigate the cognitive processes involved. The research suggests that after designated targets within the visual field have attracted preattentive indexes that point to their locations in space, conscious processes, vulnerable to secondary visual and spatial task interference, form deliberate strategies beneficial to the tracking task, before tracking commences. Target tracking itself is realized by central executive processes, which are sensitive to any other cognitive demands. The findings are discussed in the context of integrating dynamic spatial cognition within a working memory framework.