Effects of methylphenidate (Ritalin) on selective attention in hyperactive children

This study investigated the effect of methylphenidate (Ritalin) on the selective attention of hyperactive children designated as favorable or adverse responders to stimulant medication. Using a type II incidental learning paradigm, it was found that children in the drug condition recalled more central and less incidental stimuli than those children in the placebo condition. While no differential effects on recall were found for responder type, methylphenidate did affect the spontaneous overt labeling of central stimuli by the favorable responder group. Results were interpreted in terms of the role of methylphenidate in narrowing the focus of attention. Implications for the classification of hyperactive children as favorable and adverse responders were also discussed.This paper is based on a master's thesis completed by the first author in the Department of Psychology, University of Guelph, under the supervision of the second author. The authors wish to thank J. Thomas Dalby for his assistance in the conducting of this experiment.     

The computer and eye processing pictures: The implementation of a raster graphics device

The process of solving visual analogies was examined using a digital video display and video-based eye tracker. The results indicated that increasing the complexity of an analogy by increasing the number of relations involved in the problem resulted primarily in increasing the time it takes to discover the mapping between the two members of the first pair. The display of the picture and the analysis of the eye fixations are described.     

How young children represent sentences: Evidence from the superiority of noun recall from action as compared to stative sequences

Children of the ages of 4 and 7 years recalled nouns from subject-verb-object sentences more efficiently than from noun pairs. Verbs were either stative or active. Preschoolers recalled more nouns from active than stative phrases, whereas the older children showed no such difference, either in a blocked (Experiment 1) or mixed list (Experiment 2) design. Whereas interaction rather than action seems critical for older children, younger children seem better able to retrieve words from action than from stative representations.     

The effects of incorrect pain expectations on acquired fear and pain responses

Previous experimental research on the effects of incorrect intensity expectations of aversive events can be criticized because intensity expectations were not manipulated independently from changes in objective intensity. The present study aims at investigating the effects of incorrect intensity expectations on the immediate and later responses to a painful stimulus, and on the acquisition of anticipatory responses, with proper experimental control. Subjects (n = 62) received 20 painful stimuli of varying intensity. In the control group intensities were correctly signalled on all trials by an analogue signal. On 3 trials the signal was too large in the overprediction condition, and too small in the underestimation condition. Underpredicted painful experiences were related to subsequent higher pain responses on the physiological level, but not on the subjective level; and to increased anticipatory responses (increased pain expectations, uncertainty, subjective fear, skin conductance responses). Skin conductance level also indicated increased fear after underpredicted experiences. Overpredicted painful experiences were related to a faster decrease in subjective fear compared to the control group, but did not influence other variables. The findings support the notion that underpredictions contribute to the acquistion of fear and disrupt habituation processes. The asymmetrical processing of the two kinds of incorrectly predicted experiences is discussed.