Experimentally-induced dissociation impairs visual memory

Dissociation is a phenomenon common in a number of psychological disorders and has been frequently suggested to impair memory for traumatic events. In this study we explored the effects of dissociation on visual memory. A dissociative state was induced experimentally using a mirror-gazing task and its short-term effects on memory performance were investigated. Sixty healthy individuals took part in the experiment. Induced dissociation impaired visual memory performance relative to a control condition; however, the degree of dissociation was not associated with lower memory scores in the experimental group. The results have theoretical and practical implications for individuals who experience frequent dissociative states such as patients with posttraumatic stress disorder (PTSD).     

Learning new vocabulary during childhood: Effects of semantic training on lexical consolidation and integration

Research suggests that word learning is an extended process, with offline consolidation crucial for the strengthening of new lexical representations and their integration with existing lexical knowledge (as measured by engagement in lexical competition). This supports a dual memory systems account, in which new information is initially sparsely encoded separately from existing knowledge and integrated with long-term memory over time. However, previous studies of this type exploited unnatural learning contexts, involving fictitious words in the absence of word meaning. In this study, 5- to 9-year-old children learned real science words (e.g., hippocampus) with or without semantic information. Children in both groups were slower to detect pauses in familiar competitor words (e.g., hippopotamus) relative to control words 24 h after training but not immediately, confirming that offline consolidation is required before new words are integrated with the lexicon and engage in lexical competition. Children recalled more new words 24 h after training than immediately (with similar improvements shown for the recall and recognition of new word meanings); however, children who were exposed to the meanings during training showed further improvements in recall after 1 week and outperformed children who were not exposed to meanings. These findings support the dual memory systems account of vocabulary acquisition and suggest that the association of a new phonological form with semantic information is critical for the development of stable lexical representations.     

The Hemispheric Lateralization for Processing Geometric Word/Shape Combinations: The Stroop-Shape Effect

The authors conducted 4 experiments to test whether hemispheric lateralization occurs for the processing of geometric word–shape combinations. In 3 experiments, participants responded to geometric shapes combined with geometric words (square, circle, triangle). In the 4th experiment, stimuli were combinations of geometric shapes and nongeometric words. The authors predicted that it would take longer to respond in incongruent conditions (e.g., the word “square” combined with the shape of a circle) than in congruent conditions. The authors found the strongest incongruency effects for the dominant hemisphere—that is, the left hemisphere for responding to words and the right hemisphere for responding to shapes. A Shape Interfering Properties hypothesis (SIP) is a possible explanation for these results.     

Development of the Shape Bias During the Second Year

ABSTRACT. The shape bias is an attentional preference children show for the shape of an object over other aspects of the object in a word-learning context. This bias, which aids in establishing a word-object pairing, was investigated in 12-, 18-, and 24-month-old children (n = 90) across noun, adjective, and no-label conditions. The present research presents evidence of development across this time span; there was a transition from a label reducing the chance of shape extensions to indiscriminate shape extensions to a label increasing the chance of shape extensions. This research supports the notion that children are focusing their extensions more toward shape during the course of development thereby developing a more mature and more specialized shape bias.     

Effects of 7.5% CO2 inhalation on allocation of spatial attention to facial cues of emotional expression

Increased vigilance to threat-related stimuli is thought to be a core cognitive feature of anxiety. We sought to investigate the cognitive impact of experimentally induced anxiety, by means of a 7.5% CO₂ challenge, which acts as an unconditioned anxiogenic stimulus, on attentional bias for positive and negative facial cues of emotional expression in the dot-probe task. In two experiments we found robust physiological and subjective effects of the CO₂ inhalation consistent with the claim that the procedure reliably induces anxiety. Data from the dot-probe task demonstrated an attentional bias to emotional facial expressions compared with neutral faces regardless of valence (happy, angry, and fearful). These attentional effects, however, were entirely inconsistent in terms of their relationship with induced anxiety. We conclude that the previously reported poor reliability of this task is the most parsimonious explanation for our conflicting findings and that future research should develop a more reliable paradigm for measuring attentional bias in this field.     

Using facial emotional stimuli in visual search experiments: The arousal factor explains contradictory results

For more than two decades, visual search experiments using pictures of emotional faces as stimuli have generated contradictory results. Evidence of a superior detection of angry faces compared to happy faces have been mixed with an equal amount of evidence in the opposite direction. In this article, we review this literature, and examine the hypothesis that the neglected stimulus factor of emotional arousal may explain these contradictory results. Through an extensive reanalysis of results from our own laboratory as well as from other researchers, we show that the arousal factor systematically influences the outcome of the reviewed visual search experiments, and may thus provide a key to the historical contradictions within this research field.     

Searching for emotion or race: Task-irrelevant facial cues have asymmetrical effects

Facial cues of threat such as anger and other race membership are detected preferentially in visual search tasks. However, it remains unclear whether these facial cues interact in visual search. If both cues equally facilitate search, a symmetrical interaction would be predicted; anger cues should facilitate detection of other race faces and cues of other race membership should facilitate detection of anger. Past research investigating this race by emotional expression interaction in categorisation tasks revealed an asymmetrical interaction. This suggests that cues of other race membership may facilitate the detection of angry faces but not vice versa. Utilising the same stimuli and procedures across two search tasks, participants were asked to search for targets defined by either race or emotional expression. Contrary to the results revealed in the categorisation paradigm, cues of anger facilitated detection of other race faces whereas differences in race did not differentially influence detection of emotion targets.     

Verbal Memory Deficits in Children with Less than 750 g Birth Weight

Numerous studies have documented memory deficits in very low birthweight (VLBW, < 1500 g) children, yet we know little about the nature of these memory problems. To clarify memory sequelae and examine memory deficits in relation to the degree of low birth weight, we administered the California Verbal Learning Test–Children’s Version (CVLT-C) to a regional sample of 57 < 750 g birthweight children and to groups of 53 750–1499 g birthweight children and 49 term-born controls. Group comparisons revealed significant differences between the < 750 g birthweight group and term-born children on measures of list learning, delayed recall, and inaccurate recall. In addition, the percentage improvement in correct recognitions relative to long-term delayed recall was greater in the < 750 g group than in the term-born controls. Similar differences were observed between VLBW children with and without abnormal neonatal cerebral ultrasounds (high- and low-risk groups). Differences in learning rate between the VLBW and term-born groups, and between high- and low-risk VLBW children, were evident even when vocabulary skill was covaried or when children with neurosensory deficits or IQ < 80 were excluded from analysis. The findings document deficits in verbal memory in the subset of VLBW children at greatest biological risk, and suggest that acquisition processes are selectively impaired.     

Extracorporeal Membrane Oxygenation versus Conventional Treatment: Neurodevelopmental and Social Outcomes at 24 Months

The purpose of this prospective, controlled study was to compare neurodevelopmental and social outcomes at 2 years of age for children treated with extracorporeal membrane oxygenation (ECMO; n = 25) to those of children with severe respiratory illness treated with conventional methods (CT; n = 16) and to matched, healthy full-term (FT; n = 29) children. Mothers' parenting attitudes and children's mental, motor, language, exploratory play, and social competence skills were assessed. A retrospective chart review was also undertaken to further describe the groups with respect to the results of neuroimaging, audiologic, and neuromotor examinations. The FT group had significantly higher mental, motor, and language scores as compared to the ECMO and CT groups. Groups did not differ on measures of behavior, social competence, exploratory play skills, or parental attitudes. Specifically for the ECMO group, there was a trend toward language being more problematic than other areas of development. In general, the data demonstrate that severe respiratory complications, regardless of type of treatment, place children at increased risk for neurodevelopmental difficulties.     

Regional brain activity change predicts responsiveness to treatment for stuttering in adults

Developmental stuttering is known to be associated with aberrant brain activity, but there is no evidence that this knowledge has benefited stuttering treatment. This study investigated whether brain activity could predict progress during stuttering treatment for 21 dextral adults who stutter (AWS). They received one of two treatment programs that included periodic H₂¹⁵O PET scanning (during oral reading, monologue, and eyes-closed rest conditions). All participants successfully completed an initial treatment phase and then entered a phase designed to transfer treatment gains; 9/21 failed to complete this latter phase. The 12 pass and 9 fail participants were similar on speech and neural system variables before treatment, and similar in speech performance after the initial phase of their treatment. At the end of the initial treatment phase, however, decreased activation within a single region, L. putamen, in all 3 scanning conditions was highly predictive of successful treatment progress.