The role of visual information in control of a constrained locomotor task

The nature of visually guided locomotion was examined in an experiment where subjects had to walk to targets under various conditions. Target distance was manipulated so that subjects had to (a) lengthen their paces in order to hit the target; (b) shorten their paces; (c) make no adjustments to their standard pace length at all. They did this under four visual conditions: (a) normal vision; (b) with vision restricted to a "snapshot" each time the foot that was to be placed on the target was on the ground; (c) with a snapshot each time the foot to be placed was in the swing phase; and (d) no vision after departure fro the target. The results show that the subjects succeed in reaching the target in most cases. However, the smoothness and fluidity of their movements vary significantly between conditions. Under normal vision or where visual snapshots are delivered when the pointing foot is on the ground, locomotion is smoothly regulated as the subjects approach the target. where snapshots are delivered when the pointing foot is in the swing phase, regulation becomes clumsy and ill coordinated. Where no vision is available at all during the approach, adjustments are made, but these are least coordinated of all. The results show that well-coordinated visual regulation does not require continuous visual guidance but depends on intermittent information being available at the appropriate times in the action sequence. Such timing is often more important than the total amount of information that is available for guidance.     

The development of locomotor coordination: longitudinal change and invariance

Developmental sequence, relative timing, center of gravity, and phase-plane analyses were used to study a minimum of 15 years of longitudinal, filmed data on the development of hopping in 7 children. The developmental sequences revealed common, qualitative changes in the movement of the children, although each child progressed through the changes at his/her own rate. The timing analyses showed that, in the advanced hop, the tightest limb relationships were found within the hopping leg, then between contralateral limbs of the same girdle, and then between legs and arms. Relative-timing calculations revealed (a) intralimb, timing invariances that were present in first attempts to perform the skill at age 3 and remained for 15 years across all developmental levels; (b) emergent, interlimb timings that gradually became invariant; and (c) intra- and interlimb timing showing gradual development over the 15 years. One invariant, the time between landing and deepest knee flexion, is also invariant in the walk and the run (Shapiro, Zernicke, Gregor, & Diestel, 1981). Phase plane analyses indicated that the timing of peak and zero velocities may be the coordinative constant accounting for a relative timing invariance between the two legs. Position of the body's center of gravity may explain the invariant relative time between landing and deepest knee flexion, or the explanation could lie in the "equation of constraint" regulating joint equilibrium points. The data suggest that modeling the developing hop as the evolving interaction of four vibratory systems would be promising.     

The Effect of Job Level and Amount of Information on the Evaluation of Male and Female Job Applicants

The addition of job-related information regarding an applicant's leadership ability reduced bias against female applicants applying for a managerial position.     

Children's perception of certain musical properties: scale and contour

Children's perception of scale and contour in melodies was investigated in five studies. Experimental tasks included judging transposed renditions of melodies (Studies 1 and 3), discriminating between transposed renditions of a melody (Study 2), judging contour-preserving transformations of melodies (Study 4), and judging similarity to a familiar target melody of transformations preserving rhythm or rhythm and contour (Study 5). The first and second studies showed that young children detect key transposition changes even in familiar melodies and they perceive similarity over key transpositions even in unfamiliar melodies. Young children also are sensitive to melodic contour over transformations that preserve it (Study 5), yet they distinguish spontaneously between melodies with the same contour and different intervals (Study 4). The key distance effect reported in the literature did not occur in the tasks of this investigation (Studies 1 and 3), and it may be apparent only for melodies shorter or more impoverished than those used here.     

Some observations on control by spoken words in children's conditional discrimination and matching by exclusion

This study examined matching-to-sample procedures that might result in the emergence of conditional behavior never explicitly taught. Subjects were preschool children. Two pictures were displayed as comparisons on every trial, and samples were spoken words. In baseline training preceding each of three experiments, children learned to select pictures of a dog, a table, and a banana in response to their spoken English names. Thereafter, probe trials displayed novel comparisons with baseline comparisons: one novel comparison was displayed with the dog and another with the table. The three experiments differed primarily in the nature of the samples presented on probe trials. In Experiment 1, probe samples were novel words, "JAIJAI" and "BREEL." On the probes, each of seven subjects reliably selected the novel comparisons, apparently "excluding" the familiar ones. In Experiment 2, probe samples were from the subjects' baseline. On one probe, for example, the sample was "TABLE," and the subject had to choose either the dog or the novel picture. Exclusion was logically possible because the dog had always before been incorrect in the presence of "TABLE." Under these conditions, however, only two of nine children excluded reliably. In Experiment 3, probe samples were words that had never been samples on any matching-to-sample trial, but that had controlled the children's behavior in other settings. On one probe, for example, the sample was "PENCIL," and the subject had to choose either the dog or a novel picture. Subjects virtually always excluded the former and selected the latter. Unreliable exclusion in Experiment 2, therefore, apparently resulted because the probe samples had previously served also as samples on baseline trials. Spontaneous verbalizations recorded during probing provided further data consistent with this interpretation. The study helps to define variables controlling exclusion performances by showing that such performances are more likely to occur if the sample has no prior experimental history.     

THE EFFECTIVENESS OF A CONSTANT TIME-DELAY PROCEDURE TO TEACH CHAINED RESPONSES TO ADOLESCENTS WITH MENTAL RETARDATION

The effectiveness of a 5-s constant time-delay procedure to teach three chained food preparation behaviors to four moderately retarded adolescent students was evaluated within a multiple probe design across behaviors. Results indicate that the procedure was effective in teaching all four students to make a sandwich, boil a boil-in-bag item, and bake canned biscuits. The skills maintained with at least 85% accuracy over a 3-month period. Training generalized from the school to the home setting for the 2 subjects that completed generalization probe sessions. The percentage of errors across all skills and students was less than 9%.     

PROMPTING ONE LOW-FAT,HIGH-FIBER SELECTION IN A FAST-FOOD RESTAURANT

Evidence increasingly links a high-fat, low-fiber diet to coronary heart disease and certain site cancers, indicating a need for large-scale dietary change. Studies showing the effectiveness of particular procedures in specific settings are important at this point. The present study, using an A-B-A-B design and sales data from computerized cash registers, replicated and extended previous work by showing that inexpensive prompts (i.e., signs and fliers) in a national fast-food restaurant could increase the sales of salads, a low-fat, high-fiber menu selection. Suggestions also are made pertinent to more widespread use of the procedures.     

Television Food Commericals' Effect on Children's Resistance to Temptation1

This study investigated the effect of television food commercials on children's self-control within a resistance to temptation paradigm. Commercial type, food stimulus type, and the child's sex provided the three independent variables in a 4 × 4 × 2 factorial design. Behavioral and self-report indices of temptation and control were measured. Children were significantly more tempted to transgress for the low-nutrition food, regardless of the commercial shown. Sex differences in reported degree of temptation were found. However, the television commercials did not affect the children's latency to transgress.     

A survey of celiac-sprue patients: effect of dietary restrictions on religious practices

Celiac-Sprue Disease, also referred to as Non-Tropical Sprue, is a dietary disease. Celiac-Sprue patients were asked to complete a questionnaire regarding the effect of dietary restrictions on participation in the Passover meal and reception of Communion. A pilot study suggested that subjects made changes in their religious practices because of dietary restrictions. A second, more detailed survey, was performed in which 58 subjects participated and 14 religions were represented. The results indicated that many subjects made changes in their religious practices (p less than .01), made changes on their own initiative (p less than .01), or violated diet prescribed for the disease under the religious setting versus other settings (p less than .05).