Effects of methylphenidate on sensitivity to reinforcement in children diagnosed with attention deficit hyperactivity disorder: an application of the matching law

The behavior of children diagnosed with attention deficit hyperactivity disorder (ADHD) has been hypothesized to be the result of decreased sensitivity to consequences compared to typical children. The present study examined sensitivity to reinforcement in 2 boys diagnosed with ADHD using the matching law to provide more precise and quantitative measurement of this construct. This experiment also evaluated the effects of methylphenidate (MPH) on sensitivity to reinforcement of children with ADHD. Subjects completed math problems to earn tokens under four different variable-interval (VI) schedules of reinforcement presented in random order under both medicated and nonmedicated conditions. Results showed that, in the medicated condition, the matching functions for both subjects resulted in higher asymptotic values, indicating an overall elevation of behavior rate under these conditions. The variance accounted for by the matching law was also higher under the medicated conditions, suggesting that their behavior more closely tracked the changing rates of reinforcement while taking MPH compared to placebo. Under medicated conditions, the reinforcing efficacy of response-contingent tokens decreased. Results are discussed with respect to quantifying behavioral changes and the extent to which the drug interacts with prevailing contingencies (i.e., schedule values) to influence behavioral variability.     

Adapting the cognitive interview to enhance long-term (35 years) recall of physical activities

The cognitive interview (CI) was modified for use in an epidemiological study in which respondents were asked to recall their daily physical activities from the distant past (35 years ago). In comparison to a traditional epidemiological interview, the CI elicited many more responses and also more precise responses. Several practical costs, however, were incurred by the CI: additional time to train interviewers and to conduct interviews and difficulties in coding the responses. The costs and benefits of conducting the CI are addressed, along with conceptual and methodological challenges. The article ends with an existential question: Is the CI a singular technique if it can be modified so radically for different settings?     

Exploring the limits of peripheral vision for the control of movement

The role played by peripheral visual information in the control of aiming movements is not fully understood, as is indicated by the conflicting results reported in the literature. In the present study, the authors tested and confirmed the hypothesis that the source of the conflict lies in the portion of the visual peripheral field that has been under scrutiny in the different studies. Participants (N = 60) moved a computer mouse from a fixed starting position to 1 of 3 targets under varied vision conditions. The portion of the peripheral visual field that best ensured directional accuracy of a sweeping movement was found to be located between 20 degrees and 10 degrees of visual angle, whereas the area found to favor directional accuracy of an aiming movement comprised 30 degrees through 10 degrees of visual angle.     

Worries and values

Relations of individuals' value priorities to their worries are investigated in seven samples from four cultural groups (N = 1,441). A social-cognitive analysis suggests that value priorities influence worries by increasing attention to and perception of threats to valued goals. On this basis, we generate hypotheses relating two types of worries, micro (about self and its extensions) and macro (about society and world), to 10 types of values. As predicted, giving priority to self-transcendence values (universalism and benevolence) is associated with low micro and high macro worry, whereas giving priority to self-enhancement values (power, hedonism, and--to a lesser degree--achievement) is associated with high micro and low macro worry. Meaningful associations are also found for other values. Values account for substantially more variance in macro than in micro worries.     

Performance on a mirror-drawing task by non-right-handers

Left-, mixed-, and right-handed (each n = 10, N = 30) adolescent boys who were classified on the basis of a hand preference inventory performed a mirror-drawing task with a bilateral transfer of a skill paradigm. Participants' hand preference and the magnitude of bilateral transfer of skill were assessed in terms of errors committed and time taken to complete the mirror-drawing task. Mixed-handed participants exhibited significantly less habit interference for mirror drawing, and they performed the task significantly faster than the left-handers did; the group difference was not significant for the frequency of errors committed. These groups did not differ in terms of the magnitude of bilateral transfer of skill; the trend, however, showed that the transfer of skill was minimum in mixed-handers. These findings extend the theory that mixed-handed participants' inability to transfer motor skill from one hand to the other could be attributable to their lack of a clear pattern of lateralization. Their ability to perform well either at initial or later trials may be a function of less interference from their normal motor habits.     

Numerical and arithmetical cognition: a longitudinal study of process and concept deficits in children with learning disability

Based on the stability and level of performance on standard achievement tests in first and second grade (mean age in first grade = 82 months), children with IQ scores in the low-average to high-average range were classified as learning disabled (LD) in mathematics (MD), reading (RD), or both (MD/RD). These children (n = 42), a group of children who showed variable achievement test performance across grades (n = 16), and a control group of academically normal peers (n = 35) were administered a series of experimental and psychometric tasks. The tasks assessed number comprehension and production skills, counting knowledge, arithmetic skills, working memory, the ease of activation of phonetic representations of words and numbers, and spatial abilities. The children with variable achievement test performance did not differ from the academically normal children in any cognitive domain, whereas the children in the LD groups showed specific patterns of cognitive deficit, above and beyond the influence of IQ. Discussion focuses on the similarities and differences across the groups of LD children.     

Gender bias in mothers' expectations about infant crawling

Although boys outshine girls in a range of motor skills, there are no reported gender differences in motor performance during infancy. This study examined gender bias in mothers' expectations about their infants' motor development. Mothers of 11-month-old infants estimated their babies' crawling ability, crawling attempts, and motor decisions in a novel locomotor task-crawling down steep and shallow slopes. Mothers of girls underestimated their performance and mothers of boys overestimated their performance. Mothers' gender bias had no basis in fact. When we tested the infants in the same slope task moments after mothers' provided their ratings, girls and boys showed identical levels of motor performance.     

Confirmatory factor analyses of the full and short versions of the Marlowe-Crowne Social Desirability Scale

Over the years, researchers have developed various short versions of the Marlowe-Crowne Social Desirability Scale (D. P. Crowne & D. Marlowe, 1960). The authors used confirmatory factor analyses (J. L. Arbuckle, 1997) as well as item and scale analyses to evaluate the adequacy of the full version and various short versions. Overall, the results from 232 Canadian undergraduates showed (a) that all the short versions in the present study are a significant improvement in fit over the 33-item full scale and (b) that W. M. Reynolds's (1982) Forms A and B are the best fitting short versions. No gender differences were found for the full scale or any of the short versions. The results show that the full scale could be improved psychometrically and that the psychometrically sound short versions should be available because they require less administration time than the full scale.     

The Mackworth Clock Test: a computerized version

The Mackworth Clock Test (MCT; N. H. Mackworth, 1948) was developed to evaluate vigilance in British Air Force radar technicians during World War II. Homemade versions of the MCT have since varied with respect to both the characteristics of the device and the procedures of its administration. This article is a report on a computerized version of the MCT developed by the authors to closely emulate Mackworth's test. MCT data were collected from 25 undergraduate students; their performance was found to be equivalent to Mackworth's participants' data. This is the first MCT version that has been validated against the original.     

Comparison of selected perceptual variables for backpacks with internal and external frames

Differences in perceptions of comfort, exertion, balance, and heart rate were investigated with two types of backpack. Subjects were 20 male volunteers (M age = 24.3 yr., SD: 3.6, M height = 180.02 cm, SD: 8.0, and M weight = 86.46 kg, SD: 14.84). Following oral briefing and practice trials, each subject was fitted at random with either an internal- or external-frame backpack containing 18.2 kg. By random, cross-over design, subjects completed a 30-m simulated hiking trial consisting of 16 separate obstacles designed to resemble actual off-trail hiking. Trials were conducted in a controlled environment with the walking intensity regulated by a metronome. Upon completion of each trial, the subjects rated the experience on perceived comfort, balance and stability, and rating of perceived exertion. Heart rate was recorded immediately prior to and following each trial. Analysis yielded a significant difference only on rating of perceived exertion in favor of the internal-frame backpack. Under limited circumstances, these data suggest that both types of backpacks provide similar comfort and balance and stability; however, internal frames in backpacks may reduce perceived exertion during short, demanding hikes.