Horse-race model simulations of the stop-signal procedure

In the stop-signal paradigm, subjects perform a standard two-choice reaction task in which, occasionally and unpredictably, a stop-signal is presented requiring the inhibition of the response to the choice signal. The stop-signal paradigm has been successfully applied to assess the ability to inhibit under a wide range of experimental conditions and in various populations. The current study presents a set of evidence-based guidelines for using the stop-signal paradigm. The evidence was derived from a series of simulations aimed at (a) examining the effects of experimental design features on inhibition indices, and (b) testing the assumptions of the horse-race model that underlies the stop-signal paradigm. The simulations indicate that, under most conditions, the latency, but not variability, of response inhibition can be reliably estimated.     

Pathways to violence in the children of mothers who were depressed postpartum

The impact of postnatal depression on a child's risk for violent behavior was evaluated in an urban British community sample (N=122 families). Mothers were interviewed during pregnancy, at 3 months postpartum, and when the child was 1, 4, and 11 years of age. Mothers, teachers, and children reported on violent symptoms at age 11. Structural equation modeling revealed that the child's violence was predicted by the mother's postnatal depression even when her depression during pregnancy, her later history of depression, and family characteristics were taken into account. Violence was associated with symptoms of attention-deficit/hyperactivity disorder and problems with anger management. Children were most violent if mothers had been depressed at 3 months and at least once thereafter.     

Dual prism adaptation: calibration or alignment?

Dual adaptation to different amounts or directions of prismatic displacement, or both, can be acquired and maintained with little mutual interference. Associative recalibration of the regional task- or workspace, contingent on differentiation of distinguishing sensory information, can explain such adaptation. In contrast, nonassociative realignment restores dimensional mapping among spatial representations. Methods for measuring the separate contributions of those 2 kinds of prism adaptation are identified in the present article. On the basis of a critique of dual-adaptation studies, the authors suggest that recalibration can explain the data but that the method used in those experiments confounded realignment and might have obscured the effectiveness of dual-calibration training.     

Recognising facial expression from spatially and temporally modified movements

We examined how the recognition of facial emotion was influenced by manipulation of both spatial and temporal properties of 3-D point-light displays of facial motion. We started with the measurement of 3-D position of multiple locations on the face during posed expressions of anger, happiness, sadness, and surprise, and then manipulated the spatial and temporal properties of the measurements to obtain new versions of the movements. In two experiments, we examined recognition of these original and modified facial expressions: in experiment 1, we manipulated the spatial properties of the facial movement, and in experiment 2 we manipulated the temporal properties. The results of experiment 1 showed that exaggeration of facial expressions relative to a fixed neutral expression resulted in enhanced ratings of the intensity of that emotion. The results of experiment 2 showed that changing the duration of an expression had a small effect on ratings of emotional intensity, with a trend for expressions with shorter durations to have lower ratings of intensity. The results are discussed within the context of theories of encoding as related to caricature and emotion.     

Confirmatory factor analysis of the WMS-III in patients with temporal lobe epilepsy

Five competing models specifying the factor structure underlying the Wechsler Memory Scale-Third Edition (D. Wechsler, 1997b) primary subtest scores were evaluated in a sample of patients with intractable temporal lobe epilepsy (N = 254). Models specifying separate immediate and delayed constructs resulted in inadmissible parameter estimates and model specification error. There were negligible goodness-of-fit differences between a 3-factor model of working memory, auditory memory, and visual memory and a nested--more parsimonious--2-factor model of working memory and general memory. The results suggest that specifying a separate visual memory factor provides little advantage for this sample--an unexpected finding in a population with lateralized dysfunction, for which one might have predicted separate auditory and visual memory dimensions.     

Bulimics' responses to food cravings: is binge-eating a product of hunger or emotional state?

This study examined the roles of hunger, food craving and mood in the binge-eating episodes of bulimic patients, and identified the critical factors involved in the processes surrounding binge-eating episodes that follow cravings. This was a prospective study of the binge-eating behaviour of 15 women with bulimia nervosa. The participants used food intake diaries and Craving Records to self-monitor their nutritional behaviour, hunger levels and affective state. Cravings leading to a binge were associated with higher tension, lower mood and lower hunger than those cravings not leading to a binge. Levels of tension and hunger were the critical discriminating variables. The findings of the study support empirical evidence and models of emotional blocking in binge-eating behaviour and challenge the current cognitive starve-binge models of bulimia. The role of food cravings in the emotional blocking model is discussed in terms of a classically conditioned motivational state. Implications for treatment are addressed.     

Extracting parity and magnitude from Arabic numerals: developmental changes in number processing and mental representation.

Children from Grades 2, 3, 4, 6, and 8 (7.8, 9.2, 9.8, 11.7, and 13. 6 years old, respectively) made speeded, bimanual parity (odd/even) judgments of the Arabic numerals 0-9. Analysis of response times indicated that from fourth grade on, parity information is retrieved directly from memory rather than being extracted by means of a mental calculation strategy. As early as Grade 3, children exhibited the SNARC (Spatial-Numerical Association of Response Codes) effect, where small numbers were responded to faster with the left hand than with the right hand, while the converse held true for large numbers. This finding, previously demonstrated only in adults, confirms that (a) children represent magnitude information in the form of a left-to-right oriented mental number line, and (b) this information is accessed obligatorily even when irrelevant. Finally, although the SNARC effect remained strong at Grade 4, it was attenuated at Grades 6 and 8 by a linguistic effect based on associations between the unmarked adjectives "even" and "right" and between the marked adjectives "odd" and "left." Copyright 1999 Academic Press.     

REMEDIATION OF NEGATIVE SIDE EFFECTS OF AN ON-GOING RESPONSE-COST SYSTEM WITH CHRONIC MENTAL PATIENTS1

Response-cost procedures within a token economy with extremely regressed residents excluded many residents from access to positive reinforcement. Procedures allowing residents to “purchase eligibility” to obtain backup reinforcers through contingent payment on standing fines, combined with proportional fine payoff schedules contingent upon time without new fines, increased payment on fines, reduced incidence of new fines, and increased utilization of backup reinforcers. These modifications removed adverse side effects while retaining the benefits associated with response costs. Failures or adverse effects of elements of token systems should not occasion abandonment of token economies, but rather encourage their continual evaluation and modification.