Core mechanisms in "theory of mind"

Our ability to understand the thoughts and feelings of other people does not initially develop as a theory but as a mechanism. The "theory of mind" mechanism (ToMM) is part of the core architecture of the human brain, and is specialized for learning about mental states. Impaired development of this mechanism can have drastic effects on social learning, seen most strikingly in the autistic spectrum disorders. ToMM kick-starts belief-desire attribution but effective reasoning about belief contents depends on a process of selection by inhibition. This selection process (SP) develops slowly through the preschool period and well beyond. By modeling the ToMM-SP as mechanisms of selective attention, we have uncovered new empirical phenomena. We propose that early "theory of mind" is a modular-heuristic process of domain-specific learning.     

Associations in the course of personality disorders and Axis I disorders over time

In this study, the authors examined time-varying associations between schizotypal (STPD), borderline (BPD), avoidant (AVPD), or obsessive-compulsive (OCPD) personality disorders and co-occurring Axis I disorders in 544 adult participants from the Collaborative Longitudinal Personality Disorders Study. The authors tested predictions of specific longitudinal associations derived from a model of crosscutting psychobiological dimensions (L. J. Siever & K. L. Davis, 1991) with participants with the relevant Axis I disorders. The authors assessed participants at baseline and at 6-, 12-, and 24-month follow-up evaluations. BPD showed significant longitudinal associations with major depressive disorder and posttraumatic stress disorder. AVPD was significantly associated with anxiety disorders (specifically social phobia and obsessive-compulsive disorder). Two of the four personality disorders under examination (STPD and OCPD) showed little or no association with Axis I disorders.     

Normative data for the selective reminding test: a random digit dialing sample

Healthy control participants (46 women, M age=44.3 yr., SD=7.6; 29 men) were recruited to undergo a comprehensive neuropsychological battery and serve as a comparison group in a study of cognitive functioning in patients with Lyme isease. Participants were selected using Mitofsky-Waksberg random digit dialing. The Buschke 12-word, six-trial Selective Reminding Test was administered as part of the neuropsychological battery and normative data are presented stratified by age and sex. Performance on alternate forms of this measure were examined. Mean education, intelligence quotient, and Wide Range Achievement Test-3 Reading scores are reported.     

A field study of frame-of-reference effects on personality test validity

As part of a test validation study at a major U.S.-based airline, the authors tested the effects of providing an "at work" frame-of-reference on the validity of the NEO Five-Factor Inventory among a sample of customer service supervisors (N = 206). Frame-of-reference moderated the validity of the Extraversion and Openness to Experience subscales after controlling for cognitive ability. In addition, the frame-of-reference personality test showed incremental validity over cognitive ability (deltaR2 = .16), but the standard personality test did not (deltaR2 = .05). The authors' discussion focuses on implications for personality theory and research and on implications for increasing the validity of personality tests in organizational settings.     

Cerebral blood flow and anxiety in older men: an analysis of resting anterior asymmetry and prefrontal regions

Asymmetric resting blood flow in prefrontal and hemispheric regions, assessed by single photon emission computed tomography (SPECT), was examined as a potential biological marker for enhanced trait and state anxiety in 30 older men (ages 55-81). Average and asymmetric perfusion in dorsolateral, medial, and orbital regions of the prefrontal lobes was also assessed. Results indicated a significant association between lower levels of resting dorsolateral blood flow and greater state anxiety responses to a series of stressful provocations (measured on a separate occasion). A significant curvilinear (U-shaped) relation between asymmetric dorsolateral perfusion and state anxiety was also identified; increased asymmetric blood flow favoring either the right or the left dorsolateral region related to higher levels of state anxiety. However, this association was attenuated by age and systolic blood pressure. Resting perfusion in the dorsolateral region may represent a more reliable biological marker for state anxiety than trait anxiety in older men.     

Developments in long-term explicit memory late in the first year of life: behavioral and electrophysiological indices

Coincident with developments in the temporal-cortical explicit memory network, long-term recall abilities are newly emergent late in the first year of human life. We recorded event-related potentials (ERPs) in 9-month-olds as an index of the integrity of the neural substrate underlying a task thought to reflect explicit memory, namely, deferred imitation. ERP measures of recognition memory 1 week after unique laboratory experiences predicted whether and how much infants recalled of the experiences 1 month later. The findings further imply that memory storage and consolidation processes are a major source of variability in long-term recall memory late in the first year of life.     

Uncertainty in pigeons

Pigeons classified a display of illuminated pixels on a touchscreen as sparse or dense. Correct responses were reinforced with six food pellets; incorrect responses were unreinforced. On some trials an uncertain response option was available. Pecking it was always reinforced with an intermediate number of pellets. Like monkeys and people in related experiments, the birds chose the uncertain response most often when the stimulus presented was difficult to classify correctly, but in other respects their behavior was not functionally similar to human behavior based on conscious uncertainty or to the behavior of monkeys in comparable experiments. Our data were well described by a signal detection model that assumed that the birds were maximizing perceived reward in a consistent way across all the experimental conditions.     

Indexing individual objects in infant working memory

Currently there are disputes in the infancy literature concerning when infants are first able to individuate physical objects by their features or properties. This issue has taken on new significance following claims that individuation by feature is linked to the emergence of object kind concepts toward the end of the first year. Needham (2001, this issue) presents evidence that infants as young as 4.5 months old can individuate objects by feature. We locate this controversy within the framework of brain mechanisms that index or track individual objects, drawing upon theories of attention and working memory developed in the study of adults. We find that Needham's work contributes to two issues: categorization and the effect of object history on the individuation of objects in a complex display.