Predictions of X-linked inheritance for human characteristics

The conclusion reached by H. Thomas and W. Jamison (Developmental Review, 1981, 1, 274–283) that an observed sex-related difference in water-level task performance is due to an X-linked major gene raises the question of whether available data would be consistent with X-linkage predictions other than the one tested. Several predictions of X-linked inheritance for human characteristics are presented and discussed. It was concluded that although water-level task performance may involve a heritable component, the available data from seven independent studies reviewed by Thomas and Jamison are insufficient for determining the specific mode of genetic transmission.     

A reexamination of body build stereotypes

Using semantic differential and discriminant analysis techniques, the study sought to determine (a) the existence of body build stereotypes, (b) the extent of identification with these stereotypes, and (c) the effect of identification upon the child's self-evaluation. The subjects were 406 children in Grades four to eight from a midwestern community. All subjects were white and had predominantly middle-class backgrounds. Subjects completed the Piers-Harris Children's Self Concept Scale, semantic differential ratings of the Global self-concept, and the body build concepts of “SKINNY GIRL,” “FAT GIRL,” “SKINNY BOY,” and “FAT BOY,” and the situationally specific self-concepts of “MYSELF IN THE CLASSROOM,” “MYSELF AT LUNCH/RECESS,” and “MYSELF WHEN LOOKING IN A MIRROR,” Measures of weight and height were obtained using a standard weighing scale and wall chart. Fat child and skinny child stereotypes were found to be invariant across age and sex groups and did not appear to be gender specific. Actual fatness was found to be generally related to identification with the body build stereotypes, but not strongly so. Low self-esteem was a concomitant of identification with the fat child stereotype. The majority of children identified with the average child in all settings.     

Spatial perspective taking in young children.

Four- and five-year-old children were tested in a spatial perspective task employing a production format. They were shown a photograph of an aspect of a doll house and asked to generate the view on the photograph for a puppet that served as the observer. The house was mounted on a lazy Susan and could be rotated freely by the children. Puppet line of regard (to a corner, side, or rear of the house) and photograph type (fron, corner, side, or rear) constituted within-subject factors. Puppet position, photograph type, and age affected patterns of errors and proportion of correct responses. It was concluded that perspective taking is highly task dependent as well as dependent upon developmental status.     

The time course of learned helplessness, inactivity, and nociceptive deficits in rats

Four experiments are reported which explore the nature of the effects of inescapable shock on subsequent shuttlebox escape learning. The first experiment demonstrated that shuttle escape deficits dissipate within 48 hr after treatment with inescapable shock. Experiment 2 showed that exposure to inescapable shock suppressed unlearned activity in the shuttlebox and that this activity deficit recovered within 48 hr. Experiment 2A demonstrated that this shuttlebox crossing decrement was at least partly attributable to the inescapability of the shocks. These results suggested that activity factors might partly mediate the shuttle escape learning deficit reported in Experiment 1. Experiment 3 explored the possibility that activity and shuttle escape learning deficits are subserved by the effects of inescapable shock on pain sensitivity. The results supported this notion. It was found that rats were less sensitive to painful stimulation 24 hr after inescapable shock and that this analgesic tendency also dissipated within 48 hr after pretreatment. The implications of these results were discussed.     

Long-term memory in pigeons: I. The role of discrimination problem difficulty assessed by reacquisition measures II. The role of stimulus modality assessed by generalization slope

Pigeons learned either an easy or a difficult line angle discrimination (Experiment 1) or wavelength discrimination (Experiment 2), and then they were given a reacquisition test of retention after delays of 1 min, 1 day, or 1 week. Both percentage of responses to the S+ in the initial 10-trial block and number of blocks to criterion showed a progressive memory loss which was greater for the difficult problem. These results extend recent findings by using a free operant rather than a discrete trial task and by varying problem difficulty by altering the dimensional separation between training stimuli. In Experiment 3, pigeons were given variable interval training with either a wavelength or a line angle stimulus, and then they were tested for generalization in extinction after delays of 1 min, 1 day, and 1 week. With both dimensions, the relative gradients became progressively flatter with increasing delay intervals. This replicates earlier findings and extends them to the line angle dimension. The evidence of substantial forgetting in the first 24 h in all three experiments suggests that operant free-response procedures are more sensitive to forgetting effects than are discrete trial tasks.     

Time sharing and dichotic listening asymmetry in normal and learning-disabled children

Time-sharing and dichotic listening techniques were used to examine cerebral lateralization for language function in 48 normal and 48 learning-disabled children. All subjects were matched according to age, sex, and handedness. An analysis of results indicated that both nornal and learning-disabled children demonstrated left hemisphere lateralization of language function on the time-sharing and dichotic listening tasks. However, no developmental trends were evident for either group. Differences observed in the performance of the normal and learning-disabled children may relate to how each group utilizes “verbal strategies” and processes simultaneous information in the left hemisphere. The results strongly question the notion that attributes learning disabilities to incomplete or delayed language lateralization and lend support to the notion that cerebral lateralization is not a developmental phenomena.     

Effects of initial limb position on the accuracy, reaction time and electromyographic patterns of rapid movements

An experiment was performed to determine the effects of initial limb condition on final accuracy of rapid, elbow flexion movements in the horizontal plane. Electromyographic (EMG) recordings were also taken from an agonist (biceps) and antagonist (triceps) muscle by means of bipolar surface electrodes. In the experiment the subject's forearm was passively oscillated by means of an electric motor, and when an auditory buzzer sounded, the subject was required to react as quickly as possible and rapidly move to the previously learned target angle. Thus, movements could be initiated from either static or moving starting positions. The results indicated that general accuracy was not greatly affected by these manipulations, however, constant error and pre-motor reaction time suggested that subjects may have been utilizing initial limb condition information contrary to a mass-spring view. EMG data showed that the timing characteristics of the agonist and antagonist muscles were modulated, depending on the type of movement produced, supporting an impulse-timing model (Wallace 1981).     

Interactive processes in sentence comprehension and recognition

Two experiments examined the roles played by semantic and surface information in reading and recognizing sentences. Subjects read sentences in normal and inverted typography. Their recognition of meaning and other sentence features was tested using sentences whose typography, wording, and/or meaning were either the same as or different from that in the first set of sentences. In Experiment 1, subjects either read aloud or performed a sentence continuation task. For originally inverted sentences, recognition of meaning was high, irrespective of task demands. For originally normal sentences, recognition was low for Read Aloud subjects and high for Sentence Continuation subjects. Sentence recognition was affected by repetition of wording and typography. Experiment 2 replicated the results with the read aloud task and showed the second reading of originally inverted sentences to be equally swift for paraphrase and verbatim test forms. It was concluded that reading and recognition are interactive processes, involving conceptually driven and data driven operations. The interaction of operations may be either automatic or controlled. While processing of normal typography is automatic, inverted typography induces controlled processing, resulting in better retention. Furthermore, semantic and surface information are conceptualized as interacting components of comprehension and memory processes.