Directed Forgetting in Post-Traumatic-Stress-Disorder: A Study of Refugee Immigrants in Germany

Baumann M, Zwissler B, Schalinski I, Ruf-Leuschner M, Schauer M, Kißler J. Directed Forgetting in Post-Traumatic-Stress-Disorder: A Study of Refugee Immigrants in Germany. Frontiers in Behavioral Neuroscience. 2013;7:94.People with post-traumatic stress disorder (PTSD) often suffer from memory disturbances. In particular, previous studies suggest that PTSD patients perform atypically on tests of directed forgetting, which may be mediated by an altered emotional appraisal of the presented material. Also, a special role of dissociative symptoms in traumatized individuals’ memory performance has been suggested. Here, we investigate these issues in traumatized immigrants in Germany. In an item-method directed forgetting task, pictures were presented individually, each followed by an instruction to either remember or forget it. Later, recognition memory was tested for all pictures, regardless of initial instruction. Overall, the PTSD group’s discrimination accuracy was lower than the control group’s, as PTSD participants produced fewer hits and more false alarms, but the groups did not differ in directed forgetting itself. Moreover, the more negatively participants evaluated the stimuli, the less they were able to discriminate old from new items. Participants with higher dissociation scores were particularly poor at recognizing to-be-forgotten items. Results confirm PTSD patients’ general discrimination deficits, but provide no evidence for a distinct directed forgetting pattern in PTSD. Furthermore, data indicate that, in general, more negatively perceived items are discriminated with less accuracy than more positively appraised ones. Results are discussed in the larger context of emotion and stress-related modulations of episodic memory, with particular focus on the role of dissociative symptoms

Cerebral correlates of faking: Evidence from a Brief Implicit Association Test on Doping Attitudes

Direct assessment of attitudes toward socially sensitive topics can be affected by deception attempts. Reaction-time based indirect measures, such as the Implicit Association Test (IAT), are less susceptible to such biases. Neuroscientific evidence shows that deception can evoke characteristic ERP differences. However, the cerebral processes involved in faking an IAT are still unknown. We randomly assigned 20 university students (15 females, 24.65 ± 3.50 years of age) to a counterbalanced repeated-measurements design, requesting them to complete a Brief-IAT (BIAT) on attitudes toward doping without deception instruction, and with the instruction to fake positive and negative doping attitudes. Cerebral activity during BIAT completion was assessed using high-density EEG. Event-related potentials during faking revealed enhanced frontal and reduced occipital negativity, starting around 150ms after stimulus presentation. Further, a decrease in the P300 and LPP components was observed. Source analyses showed enhanced activity in the right inferior frontal gyrus between 150 and 200ms during faking, thought to reflect the suppression of automatic responses. Further, more activity was found for faking in the bilateral middle occipital gyri and the bilateral temporoparietal junction. Results indicate that faking reaction-time based tests alter brain processes from early stages of processing and reveal the cortical sources of the effects. Analyzing the EEG helps to uncover response patterns in indirect attitude tests and broadens our understanding of the neural processes involved in such faking. This knowledge might be useful for uncovering faking in socially sensitive contexts, where attitudes are likely to be concealed

It’s all in your head – how anticipating evaluation affects the processing of emotional trait adjectives

Language has an intrinsically evaluative and communicative function. Words can serve to describe emotional traits and states in others and communicate evaluations. Using electroencephalography (EEG), we investigate how the cerebral processing of emotional trait adjectives is modulated by their perceived communicative sender in anticipation of an evaluation. 16 students were videotaped while they described themselves. They were told that a stranger would evaluate their personality based on this recording by endorsing trait adjectives. In a control condition a computer program supposedly randomly selected the adjectives. Actually, both conditions were random. A larger parietal N1 was found for adjectives in the supposedly human-generated condition. This indicates that more visual attention is allocated to the presented adjectives when putatively interacting with a human. Between 400 and 700ms a fronto-central main effect of emotion was found. Positive, and in tendency also negative adjectives, led to a larger late positive potential (LPP) compared to neutral adjectives. A centro-parietal interaction in the LPP-window was due to larger LPP amplitudes for negative compared to neutral adjectives within the ‘human sender’ condition. Larger LPP amplitudes are related to stimulus elaboration and memory consolidation. Participants responded more to emotional content particularly when presented in a meaningful ‘human’ context. This was first observed in the early posterior negativity window (EPN, 210-260 ms). But the significant interaction between sender and emotion reached only trend-level on post-hoc tests. Our results specify differential effects of even implied communicative partners on emotional language processing. They show that anticipating evaluation by a communicative partner alone is sufficient to increase the relevance of particularly emotional adjectives, given a seemingly realistic interactive setting

‘Forget me (not)?’ – Remembering forget-items versus un-cued items in directed forgetting

Humans need to be able to selectively control their memories. Here, we investigate the underlying processes in item-method directed forgetting and compare the classic active memory cues in this paradigm with a passive instruction. Typically, individual items are presented and each is followed by either a forget- or remember-instruction. On a surprise test of all items, memory is then worse for to-be-forgotten items (TBF) compared to to-be-remembered items (TBR). This is thought to result from selective rehearsal of TBR, or from active inhibition of TBF, or from both. However, evidence suggests that if a forget instruction initiates active processing, paradoxical effects may also arise. To investigate the underlying mechanisms, four experiments were conducted where un-cued items (UI) were introduced and recognition performance was compared between TBR, TBF and UI stimuli. Accuracy was encouraged via a performance-dependent monetary bonus. Across all experiments, including perceptually fully matched variants, memory accuracy for TBF was reduced compared to TBR, but better than for UI. Moreover, participants used a more conservative response criterion when responding to TBF stimuli. Thus, ironically, the F cue results in active processing, but this does not have inhibitory effects that would impair recognition memory beyond a un-cued baseline condition. This casts doubts on inhibitory accounts of item-method directed forgetting and is also difficult to reconcile with pure selective rehearsal of TBR. While the F-cue does induce active processing, this does not result in particularly successful forgetting. The pattern seems most consistent with the notion of ironic processing

Role of upper and lower face half.

<p>Difference score “upper face half” minus “lower face half” for each of the 14 faces used in the experiment, with positive values indicating bigger importance of the upper face half and negative values indicating bigger importance of lower face half; a, for the female face; b, for the male face; error bars represent 95% confidence intervals.</p

Principal component analysis of face weights.

<p>a, percentage of explained variance by the first five principal components; b, visualisation of weights of each principal component in “tile space”, with positive weights in red and negative weights in blue; c, plotting each face in the space defined by the first two principal components, error bars represent 95% confidence intervals; d, same as c, but with the actual stimuli replacing the markers.</p

Example of tile weighting.

<p>a, an example of four trials with the happy female face, where the unmasking sequence was stopped as illustrated, and a correct answer was given; b, the weights of all tiles for the happy female face, based on 16 trials of one participant. The weights are visualised with a green-red colour spectrum which is min-max-scaled, so lowest weights are green and highest weights are red.</p

Representational similarity analysis (RSA).

<p>Dissimilarity (1—Pearson correlation) for all faces, projected into distances in 2D-space by means of multidimensional scaling; a, RSA with (greyscale) pixel values of images; b, RSA with tile weights from the emotion recognition task; note that axes are not labelled, as they do not represent distinct dimensions and only the distances in 2D space are interpretable.</p

Global metrics for all faces.

<p>a, for each condition, the average percentage of revealed tiles needed until a correct response is given is plotted on the x-axis; the average percentage of correct responses in plotted on the y-axis; error bars illustrate 95% confidence intervals; b and c, percentage of all responses for female (b) and male (c) faces, including confusions. Correct responses are plotted in strong colours at the bottom of each bar. Incorrect responses are plotted in muted colours and are at the top of each bar; acronyms: hap, happy; ang, angry; sup, surprised; ntr, neutral; dis, disgust; fea, fear; sad, sad.</p

Role of specific action units for emotion recognition.

<p>Colours of each action unit as drawn on the face correspond to colours of bars, which are labelled with the respective action unit according to the facial action coding system. Values indicate importance of each action unit as compared to the baseline of all non-action unit tiles. Error bars represent 95% confidence intervals.</p