Interocular transfer of movement after-effects in schizophrenia.

A group of 16 chronic schizophrenic subjects were compared with 15 age-matched control subjects for interocular transfer of movement after-effects. Contrary to the hypothesis that schizophrenic subjects would show a deficit on this measure schizophrenics showed increased transfer compared to the controls. This effect is not due to response perseveration and is not correlated with length of hospitalization, age or dose of antipsychotic drugs. It is suggested that the effect reflects a deficit in 'inhibitory processes' in schizophrenia.     

A note on the speed-amplitude function in movement control

An experiment is reported that documents the maximum average speed-amplitude relationship across the full range of motion for elbow flexion. Minimum movement time increased as a negative exponential within the movement range up to 94-97% of the maximum range of motion. At this point a discontinuity occurred with movement time increasing at an increasing rate probably due to anatomical and morphological constraints. These results suggest that the maximum average velocity-amplitude boundary to the movement speed-accuracy relationship is curvilinear. Kinematic analysis of the movements as a function of range of motion suggests that a simple pulse-step model of movement control cannot account for the present findings.     

A comparison of twins for degree of closeness and field dependency

An examination of Witkin's construct of field dependency was undertaken with a sample of adolescent twin pairs to determine if the degree of closeness in twin relationships would be reflected in the twins' degree of field dependency. Sixteen pairs of monozygotic (MZ) adolescent male twins and the same number of dizygotic (DZ) same-sexed male twins were administered three measures: Nichols and Bilbro's (1966) zygosity questionnaire, Paluszny and Beit Hallahmi's (1974) semantic differential measure of closeness, and Jackson's (1956) short form of the Embedded Figures Test. No significant differences were found between the MZ and DZ twin groups with regard to their expressed closeness to one another, as measured with Paluszny and Beit-Hallahmi's index of closeness; in addition, there were no significant differences between the two twin groups on the measure of field dependency. However, significant relationships of these two variables with intelligence were found and possible reasons for such an occurrence were offered.     

The effect of information content upon the perception and after-effects of a rotating field

From an investigation of movement after-effects induced by a rotating field, it seems that the information content of the inspection field is an important determinant of the subsequent movement after-effects (M.A.E.). This finding, considered in conjunction with phenomena evoked during perception of high information content and highly redundant fields, is discussed in connection with Anstis and Gregory's (1965) work on the role of retinal stimulation in the production of M.A.E.s.