Effects of surface texture on weight perception when lifting objects with a precision grip

In this paper, we show that, when lifting an object using a precision grip with the distal pads of the thumb and index finger at its sides, the perceived weight depends on the object’s surface texture. The smoother the surface texture, the greater the perceived weight. We suggest that a smoother object is judged to be heavier because the grip force, normal to the surface, required to prevent it from slipping is greater. The possibility of there being an influence of surface texture per se is excluded by a second experiment that employed a variant of the precision grip in which the thumb supports the weight of the object from underneath. With the grip oriented in this way, there is no need to match grip force to surface texture and, under these conditions, there is no effect of surface texture on weight perception. In the first two experiments, the test and comparison weights were lifted successively by the same hand. In a third experiment, the effect of surface texture was replicated for sequential lifts made with separate hands. Thus, the effect is not restricted to comparisons made with the same hand.     

Applications of a computer algebra system in introductory statistics

Maple, a computer algebra system, is employed in introductory statistics courses to promote conceptual learning by students of statistical principles without direct use of mathematics. Maple’s symbolic computation, graphic display, and animation capabilities support an integrated set of procedures for active study of sampling distributions and concepts related to samples, populations, and statistical decision making, error, and power. Students select parameter values for one-line commands and examine the effects of alternatives on computer-generated graphical representations of distributions. The 20 procedures written to support active student exploration of basic statistical concepts are described, and examples of exercises to support their use are provided.     

A Playroom Observation Procedure to Assess Children with Mental Retardation and ADHD

Forty-two children (ages 6 to 12 years old) with moderate mental retardation to borderline intellectual functioning were studied in a laboratory playroom setting to determine whether children identified as ADHD (attention deficit hyperactivity disorder) or controls differed on activity and attentional measures. Children with ADHD were further divided into ADHD + conduct problems (ADHD + CD) and ADHD-only subgroups (with an ADHD-combined group comprising children of both subgroups). An interval recording system was used to code observations of independent play and a restricted academic task. Results indicated that the ADHD-combined group was significantly more vocal and engaged in a significantly greater number of toy changes than controls during independent play. Significant group differences were also noted during the restricted academic task, with the ADHD-combined and ADHD + CD groups more off-task and engaging in a greater number of toy touches than controls. Discriminant analyses found independent play measures to predict group membership in 70 percent of cases (ADHD-combined vs. controls), but in only 64 percent of cases using measures from the restricted academic task. No significant findings resulted when the ADHD subjects were further divided into two subgroups. Despite some inconsistent findings, such laboratory-based observations may be of value in the diagnosis of ADHD in children with moderate mental retardation to borderline intellectual functioning.     

Behavior of neonates exposed in utero to methadone as assessed on the Brazelton scale

Twenty-nine infants exposed in utero to methadone and 37 comparison infants were examined on the Neonatal Behavioral Assessment Scale at early and late neonatal ages. All infants were full-term at birth, over 2500 g, and not yet circumcised at the early assessment. None of the methadone-exposed infants were breast-fed or were being treated pharmacologically for withdrawal. During the first week of life, methadone-exposed neonates differed from comparison ones in motoric behavior. Relative to comparison-group infants, they were jerkier and more tremulous, tense, active, and better able to put hand in mouth. By the end of the first month these differences diminished, although there was still a tendency for the methadone-exposed infants to have elevated body tonus. Neither perinatal complications, birth weight, nor sex of infant could explain the early neonatal differences between the methadone and comparison groups. Past the early stage of acute withdrawal, neonates exposed prenatally to methadone behave not unlike their nonexposed peers.     

Word-finding as a function of stimulus context: Children compared with aphasic adults

A study of object naming in 202 children, aged 5–11 years, demonstrated that varying the stimulus context affected the level of response accuracy. From age 6 to 10, completing a sentence with a noun (auditory) yielded the lowest error scores, naming objects upon hearing a definition (also auditory) produced most errors, while responding with names to pictured objects was of intermediate difficulty. This is the same order of object naming difficulty found in adult aphasic patients. Children older than 10 do not appear to be affected by stimulus context in their object naming. Results are discussed in terms of the relative syntactic difficulty of the two auditory conditions, the unexpected sex differences, and the “aphaseoid” naming errors of children.     

The inferiority game: Perceptions and behavior

Other-sex perceptions and actual reported behavior of 318 college males and 287 college females were compared for four dating situations. The average degree of inaccuracy (disregarding direction) for males was 29.0%, while for women it was 12.5%. Conclusions support other research indicating superior role-taking ability on the part of females. The issues of cultural transmission and pluralistic ignorance are discussed as they affect male and female interaction. Important research implications for human relations and the family in particular are noted.     

Polysemy and the acquisition of the cognitive internal state lexicon

Previous research (Hall, Scholnick, & Hughes, 1987) suggested that cognitive word meanings denote six increasingly abstract and complex cognitive processes. In this paper, we further investigated two interrelated aspects of this framework. A set of 36 conversations with children aged 4:5 to 5 provided the data. In Study 1, issues related to the optimal ordering of levels were examined by comparing the original sequence with a restructured model. In Study 2, the hypothesis that, in addition toknow, other polysemous cognitive internal state words would be hierarchically organized was tested. The findings lent support to the restructured model, but rejected the hypothesis that polysemous words within the domain were characterized by equivalent,hhierarchically organized levels. We conclude by proposing that cognitive internal state words were related by complementarity of levels rather than equivalence.The research on which this paper is based was supported by a grant from the Carnegie Corporation of New York to William S. Hall. Data analysis was supported by the Computer Science Center at the University of Maryland, College Park.     

The development of therapeutic consultations in child-focused family work

This paper outlines the theoretical influences that have led to our use of a consultation approach to work with children and families. Winnicott's notion of therapeutic consultation, the narrative approach in family therapy, the use of letters in therapeutic work and the two-plus-one model of therapeutic contact are discussed. A model of the consultation interview and process is presented together with examples of consultation letters responding to typical client expectations of the process.     

Attentional scanning and space errors

Using the method of paired comparisons, pairs of simultaneous horizontal or vertical lines, with one line above and one below or one on the left and one on the right of a fixation point, respectively, were presented tachistoscopically for length comparison. Space errors were found to have a pattern similar to that of time errors. The tendency to guess the comparative response from the absolute magnitude of stimuli is proposed as a basis for time and space errors. Manipulation of attentional scanning, which implies a more frequent usage of this guessing strategy for one of the two lines in a pair, was shown to affect space errors.     

Speech imagery is not always faster than visual imagery

One approach to the study of mental imagery is to examine the performance characteristics of different forms of mental imagery when used in various tasks. To demonstrate the utility of this functional approach, the use of speech and visual imagery processes in the serial mental rehearsal of common verbal sequences le.g., letters of the alphabet and familiar object arrays (objects found in familiar rooms) was examined in the present experiments. Rehearsal rates and self-reporte were consistent with the hypothesis that mental rehearsal efficiency is a function of the compatibility of characteristics of the rehearsal materials and rehearsal mode. While verbal sequences were rehearsed faster under speech than under visual imagery conditions, object arrays were rehearsed as fast under visual as under speech imagery conditions. In addition, evidence was found that covert verbal rehearsal is faster than overt verbal rehearsal under some circumstances.