Event-related potential correlates of interference effects on recognition memory

The question of interference (how new learning affects previously acquired knowledge and vice versa) is a central theoretical issue in episodic memory research, but very few human neuroimaging studies have addressed this question. Here, we used event-related potentials (ERPs) to test the predictions of the complementary learning systems (CLS) model regarding how list strength manipulations (strengthening some, but not all, items on a study list) affect recognition memory. Our analysis focused on the FN400 old-new effect, a hypothesized ERP correlate of familiarity-based recognition, and the parietal old-new effect, a hypothesized ERP correlate of recollection-based recognition. As is predicted by the CLS model, increasing list strength selectively reduced the ERP correlate of recollection-based discrimination, leaving the ERP correlate of familiarity-based discrimination intact. In a second experiment, we obtained converging evidence for the CLS model’s predictions, using a remember/know test: Increasing list strength reduced recollection-based discrimination but did not reduce familiarity-based discrimination.     

Event-related brain potentials differentiate normal and disabled readers

Auditory event-related potentials (AERPs) recorded to irrelevant tone pairs while subjects performed visual, reading-related cognitive tasks differed significantly between normal and disabled readers. Disabled readers as compared with normal readers showed significantly lower amplitude right hemisphere AERP responses during tasks that involved visual-phonemic transfer of information and simple pattern recognition. Disabled readers as compared with normal readers also showed significantly higher amplitude left hemisphere responses during the visual-phonemic task. In both experimental conditions the reading-disabled subjects showed significantly lower amplitude right than left hemisphere AERP responses. Task-related strategies did not differ between groups. The pattern of AERP amplitude asymmetry found for disabled readers, which was opposite to that found for normal readers, suggests that the same reading-related tasks activated different cerebral processes in the two groups studied.     

The perception of /r/ and /l/ in syllable-initial and syllable-final position

American English liquids /r/ and /l/ have been considered intermediate between stop consonants and vowels acoustically, articulatorily, phonologically, and perceptually. Cutting (1947a) found position-dependent ear advantages for liquids in a dichotic listening task: syllable-initial liquids produced significant right ear advantages, while syllable-final liquids produced no reliable ear advantages. The present study employed identification and discrimination tasks to determine whether /r/and /l/ are perceived differently depending on syllable position when perception is tested by a different method. Fifteen subjects listened to two synthetically produced speech series—/li/ to /ri/ and /il/ to /ir/—in which stepwise variations of the third formant cued the difference in consonant identity. The results indicated that: (1) perception did not differ between syllable positions (in contrast to the dichotic listening results), (2) liquids in both syllable positions were perceived categorically, and (3) discrimination of a nonspeech control series did not account for the perception of the speech sounds.     

Representational momentum in scenes: Learning spatial layout

In four experiments, we examined whether watching a scene from the perspective of a camera rotating across it allowed participants to recognize or identify the scene's spatial layout. Completing a representational momentum (RM) task, participants viewed a smoothly animated display and then indicated whether test probes were in the same position as they were in the final view of the animation. We found RM anticipations for the camera's movement across the scene, with larger distortions resulting from camera rotations that brought objects into the viewing frame compared with camera rotations that took objects out of the viewing frame. However, the RM task alone did not lead to successful recognition of the scene's map or identification of spatial relations between objects. Watching a scene from a rotating camera's perspective and making position judgments is not sufficient for learning spatial layout.     

Social anxiety in body dysmorphic disorder

Although clinical impressions suggest that patients with body dysmorphic disorder (BDD) experience distress in social situations, social anxiety in BDD has received little investigation. This study examined social anxiety in 81 patients with BDD and change in social anxiety with pharmacotherapy. Subjects completed the Social Avoidance and Distress Scale (SADS) and were assessed with measures of BDD symptomatology. Participants in a placebo-controlled fluoxetine trial completed measures at baseline and endpoint. The mean SADS score was 1.3 SD units higher than nonclinical sample means but consistent with other clinical sample means. Social anxiety was significantly correlated with BDD severity. Greater depressive symptoms as well as comorbid avoidant personality disorder, but not comorbid social phobia, were also associated with higher SADS scores. Social anxiety did not improve more with fluoxetine than placebo, yet it improved significantly more in fluoxetine responders than in nonresponders. Understanding social anxiety in BDD has implications for reducing rates of misdiagnosis and treatment dropout.     

Development of gender labeling: Effect of age of pictured children

Toddlers (27 girls and 25 boys) between 20 and 42 months of age were given three gender discrimination tasks, each consisting of 12 pairs of photographs of girls and boys at one of three age levels: 3, 8, or 13 years. The subject's task was to point to the designated target (girl or boy) on each trial. Subjects' gender discrimination improved with age, with a fairly sharp transition from chance to accurate responding occurring at approximately 29 months. The age of pictured children did not affect performance.     

Linking sounds to meanings: Infant statistical learning in a natural language

The processes of infant word segmentation and infant word learning have largely been studied separately. However, the ease with which potential word forms are segmented from fluent speech seems likely to influence subsequent mappings between words and their referents. To explore this process, we tested the link between the statistical coherence of sequences presented in fluent speech and infants’ subsequent use of those sequences as labels for novel objects. Notably, the materials were drawn from a natural language unfamiliar to the infants (Italian). The results of three experiments suggest that there is a close relationship between the statistics of the speech stream and subsequent mapping of labels to referents. Mapping was facilitated when the labels contained high transitional probabilities in the forward and/or backward direction (Experiment 1). When no transitional probability information was available (Experiment 2), or when the internal transitional probabilities of the labels were low in both directions (Experiment 3), infants failed to link the labels to their referents. Word learning appears to be strongly influenced by infants’ prior experience with the distribution of sounds that make up words in natural languages.     

Family-focused cognitive behaviour therapy versus psycho-education for adolescents with chronic fatigue syndrome: Long-term follow-up of an RCT

The aim of this study was to investigate the long term efficacy of family-focused cognitive behaviour therapy (CBT) compared with psycho-education in improving school attendance and other secondary outcomes in adolescents with chronic fatigue syndrome (CFS). A 24 month follow-up of a randomised controlled trial was carried out. Participants received either 13 one-hour sessions of family-focused CBT or four one-hour sessions of psycho-education. Forty-four participants took part in the follow-up study. The proportion of participants reporting at least 70% school attendance (the primary outcome) at 24 months was 90% in CBT group and 84% in psycho-education group; the difference between the groups was not statistically significant (OR = 1.29, p = 0.80). The proportion of adolescents who had recovered in the family-focused CBT group was 79% compared with 64% in the psycho-education, according to a definition including fatigue and school attendance. This difference was not statistically significant (Fisher's exact test, p = 0.34). Family-focused CBT was associated with significantly better emotional and behavioural adjustment at 24 month follow-up compared to psycho-education, as reported by both adolescents (F = 6.49, p = 0.02) and parents (F = 4.52, P = 0.04). Impairment significantly decreased in both groups between six and 24 month follow-ups, with no significant group difference in improvement over this period. Gains previously observed for other secondary outcomes at six month follow-up were maintained at 24 month follow-up with no further significant improvement or group differences in improvement. In conclusion, gains achieved by adolescents with CFS who had undertaken family-focused CBT and psycho-education generally continued or were maintained at two-year follow-up. The exception was that family-focused CBT was associated with maintained improvements in emotional and behavioural difficulties whereas psycho-education was associated with deterioration in these outcomes between six and 24-month follow-up.