Traumatic memories of war veterans: not so special after all

Several authors have argued that traumatic experiences are processed and remembered in a qualitatively different way from neutral events. To investigate this issue, we interviewed 121 Croatian war veterans diagnosed with posttraumatic stress disorder (PTSD) about amnesia, intrusions (i.e., flashbacks and nightmares), and the sensory qualities of their most horrific war memories. Additionally, they completed a self-report scale measuring dissociative experiences. In contrast to what one would expect on the basis of theories emphasizing the special status of traumatic memories, amnesia, and high frequency intrusions were not particularly typical for our sample of traumatized individuals. Moreover, traumatic memories were not qualitatively different from neutral memories with respect to their stability and sensory qualities. The severity of PTSD symptoms was not significantly correlated with dissociative experiences. Our findings do not support the existence of special memory mechanisms that are unique to experiencing traumatic events.     

Language and false belief: evidence for general, not specific, effects in cantonese-speaking preschoolers

Two studies were conducted with Cantonese-speaking preschoolers examining J. de Villiers's (1995) hypothesis that syntactic complements play a unique role in the acquisition of false belief (FB). In Study 1, the authors found a positive correlation between FB and syntactic complements in 72 four- to six-year-old Cantonese-speaking preschoolers. Study 2 followed 72 three- to five-year-old Cantonese-speaking children who initially failed an FB screening task and were then tested on general language abilities, short-term memory, inhibition, nonverbal IQ, and on FB and complement tasks. Once age and initial FB understanding were controlled for in both multiple regression and hierarchical linear modeling analyses, complements no longer uniquely predicted FB. Instead, individual differences in general language abilities and short-term memory contributed to the variation in both complements and FB.     

Is masked neighbor priming inhibitory? Evidence using the incremental priming technique

To investigate neighbor effects in visual word recognition, the masked priming technique holds considerable advantages over unprimed methods, because a target word is used as its own control. However, inhibitory neighbor effects obtained with masked priming are still open for different interpretations, because the primes differ across conditions. Given this theoretical problem, it is useful to investigate neighbor priming effects using a prime as its own control. This option is available in the incremental priming technique (Jacobs, Grainger, & Ferrand, 1995), in which a within-condition baseline is created by comparing the response times (RTs) to a target when it is primed at different prime durations. In this study, we examined masked neighbor priming using this technique. Both the traditional and the within-condition baseline indicated that masked neighbor word priming is inhibitory in nature. The results are discussed in terms of current theories of visual word recognition.     

Natural variation in Drosophila larval reward learning and memory due to a cGMP-dependent protein kinase

Animals must be able to find and evaluate food to ensure survival. The ability to associate a cue with the presence of food is advantageous because it allows an animal to quickly identify a situation associated with a good, bad, or even harmful food. Identifying genes underlying these natural learned responses is essential to understanding this ability. Here, we investigate whether natural variation in the foraging (for) gene in Drosophila melanogaster larvae is important in mediating associations between either an odor or a light stimulus and food reward. We found that for influences olfactory conditioning and that the mushroom bodies play a role in this for-mediated olfactory learning. Genotypes associated with high activity of the product of for, cGMP-dependent protein kinase (PKG), showed greater memory acquisition and retention compared with genotypes associated with low activity of PKG when trained with three conditioning trials. Interestingly, increasing the number of training trials resulted in decreased memory retention only in genotypes associated with high PKG activity. The difference in the dynamics of memory acquisition and retention between variants of for suggests that the ability to learn and retain an association may be linked to the foraging strategies of the two variants.     

Recovery from object substitution masking induced by transient suppression of visual motion processing: a repetitive transcranial magnetic stimulation study

Object substitution masking is a form of visual backward masking in which a briefly presented target is rendered invisible by a lingering mask that is too sparse to produce lower image-level interference. Recent studies suggested the importance of an updating process in a higher object-level representation, which should rely on the processing of visual motion, in this masking. Repetitive transcranial magnetic stimulation (rTMS) was used to investigate whether functional suppression of motion processing would selectively reduce substitution masking. rTMS-induced transient functional disruption of cortical area V5/MT+, which is important for motion analysis, or V1, which is reciprocally connected with V5/MT+, produced recovery from masking, whereas sham stimulation did not. Furthermore, masking remained undiminished following rTMS over the region 2 cm posterior to V5/MT+, ruling out nonspecific effects of real stimulation and confirming regional specificity of the rTMS effect. The results suggest that object continuity via the normal function of the visual motion processing system might in part contribute to this masking. The relation of these findings to the reentrant processing view of object substitution masking and other visual phenomena is discussed.     

Acute dissociation after 1 night of sleep loss

Recent research has shown that dissociative symptoms are related to self-reports of deviant sleep experiences. The present study is the 1st to explore whether sleep loss can fuel dissociative symptoms. Twenty-five healthy volunteers were deprived of sleep for 1 night. Sleepiness and dissociative symptoms were assessed every 6 hr. The authors measured both spontaneous dissociative symptoms and dissociative symptoms induced by dot-staring during sensory deprivation. Sleepiness as well as spontaneous and induced dissociative symptoms were stable throughout the day but increased during the night. These findings provide further evidence for a robust relationship between disruptions in sleep patterns and dissociative symptoms.     

Global VOR gain adaptation during near fixation to foveal targets

Long-term rotational vestibulo-ocular (VOR) adaptation occurs during systematic dysmetria between visual and vestibular afferents, adjusting eye-rotation angular velocity to re-establish retinal stability of the visual field. Due to translational motion of the eyes during head rotation, VOR gain is higher when fixating near objects. The current study measures VOR in humans before and after 6 min of exposure to a foveal near-target during sinusoidal whole-body rotation at 0.45 Hz. All of six participants showed post-exposure increases in open-loop VOR gain after fixating near targets, demonstrating a mean modulation increase of open-loop VOR gain from 0.86 before adaptation to 1.2 after adaptation. We discuss a number of theoretical and applied implications.     

Statistical information and coarticulation as cues to word boundaries: a matter of signal quality

We investigated how statistical information in the form of transitional probabilities (TPs) interacts with coarticulation, another sublexical cue to word boundaries, and examined the impact of signal quality on the weighting of these cues. In an artificial-language-learning setting, with phonetically intact speech, coarticulation overruled TPs, suggesting the predominance of subsegmental, low-level information. However, whereas the role of coarticulation in segmentation was highly modulated by signal quality, TPs were very resilient to noise. When coarticulation was rendered unreliable by strongly degrading the input with a 10-dB signal-to-noise ratio (SNR), only statistical information drove segmentation. In a more mildly degraded 22-dB SNR condition, in which some acoustic properties were still available, coarticulation was exploited, although with less reliability than in optimal conditions. These results can be interpreted according to a hierarchical approach (Mattys, White, & Melhorn, 2005) in which both the available segmentation cues and the listening conditions have an important role in speech segmentation.     

Levels of specificity of autobiographical memories and of biographical memories of the deceased in bereaved individuals with and without complicated grief

Traumatized individuals experiencing posttraumatic stress have difficulty retrieving specific autobiographical memories to cue words on the Autobiographical Memory Test (AMT; J. M. G. Williams & K. Broadbent, 1986). This may represent a generalized, functional avoidance of the personal past. However, such individuals also often report specific intrusive memories of their trauma in the day-to-day. This raises the possibility that memories tied to the source of the person's distress are immune to this putative avoidance process. This was investigated in bereaved individuals with complicated grief (CG) who reported intrusive, specific memories from the life of their deceased loved one, and matched bereaved controls without CG. Participants performed the AMT and two Biographical Memory Tests (BMTs), cueing memories from the life of the deceased (BMT-Deceased) and from a living significant other (BMT-Living). To negative word cues, the CG group showed reduced specificity for the AMT and BMT-Living, relative to controls, but this effect was reversed on the BMT-Deceased. These data support the proposal that memories tied to the source of an individual's distress are immune to the processes that underlie the standard reduced specificity effect.     

Is death really the worm at the core? Converging evidence that worldview threat increases death-thought accessibility

According to terror management theory, if the cultural worldview protects people from thoughts about death, then weakening this structure should increase death-thought accessibility (DTA). Five studies tested this DTA hypothesis. Study 1 showed that threatening Canadian participants' cultural values (vs. those of another culture) increased DTA on a word-fragment completion task. Study 2 showed that when participants could dismiss the threat, DTA remained low. Study 3 replicated the results of Study 1, but DTA was measured using a lexical decision task. Response latencies to death, negative, and neutral content were measured. Worldview threat increased DTA relative to accessibility for negative and neutral content. Study 4 showed that the DTA effect emerged independently of the arousal of anger or anxiety. Finally, Study 5 demonstrated that participants with a pro-creation (vs. pro-evolution) worldview had higher DTA after reading an anti-creation article. Discussion focused on theoretical implications and directions for further research.