Future Research Directions in Laterality

This paper considers the current conceptual state of research into neuropsychological laterality and considers some issues which might appropriately be considered for the forward development of the field. It considers the biological context which has been adopted for these studies and the psychological significance of performance asymmetries. A principal emphasis of the paper is the degree to which inferences, rather than direct methodological deductions, can be drawn from the research undertaken. The status of the dichotomies which have been proposed, the role of interhemispheric transfer, and stages of processing models are considered. The degree to which cerebral asymmetries may be inferred to reflect normal processes of the brain is questioned, and some prospects of the future discussed.     

Interhemispheric transfer of figural information in right- and non-right-handed subjects.

The capacity of normal human Ss to match abstract shapes across the cerebral hemispheres was studied as a function of exposure duration. A general right hemisphere superiority was found, and in the conditions where one stimulus was presented to each hemisphere, the order of stimuli (to the right or left hemisphere first) did not affect performance. Decreasing stimulus exposure was shown to interact with hemisphere differences. An overall superiority of non-right-handed subjects was found, although their pattern of results did not differ from right-handed Ss, and it is argued that this supports the hypothesis that the cerebral organisation of the non-right-hander is more diffuse in its general organisational structure.     

Transfer between the cerebral hemisphere in human learning

Meaningless paired-associate duograms were presented with one member directed to each cerebral hemisphere, and the test stimulus directed to either the same or different hemisphere as that of original presentation. No differences were found between these conditions or between left- or right-handed subjects. In association with other experimental work on interhemispheric learning effects, it can be concluded that presentation to the left or to both hemispheres leads to bilateral learning, while presentation to the right hemisphere alone results only in learning in that hemisphere.     

Hemispheric control of hand function in the human brain

The cerebral dominance argument holds that the hand is representative of the functions of the hemisphere by which it is controlled. An influx of visual information to that hemisphere should result in a disruption of simultaneous performance by the hand. This view was tested by requiring the subject to perform a sorting task with one hand whilst at the same time performing a visual task on which information was projected either to the hemisphere relating to hand performance or to its opposite member. Visual information projected to the same hemisphere does not interfere with the performance of the hand. This suggests that control of hand function can be switched from one hemisphere to the other as the need arises.     

Identity Processing Styles and Psychosocial Balance during Early and Middle Adulthood: The Role of Identity in Intimacy and Generativity

Identity styles and Eriksonian psychosocial balance were examined in young adults (N = 163; 64.4% women) and middle-aged adults (N = 132; 51.5% women). Participants completed self-report measures of identity styles (informational, normative, and diffuse-avoidant), identity commitment, and psychosocial balance (identity, intimacy, and generativity). Different patterns of psychosocial balance were found for each identity style, with largely consistent findings across age groups. The diffuse-avoidant style was negatively associated with all forms of psychosocial balance, the normative style was positively associated with identity and intimacy balance, and the informational style was positively associated with intimacy and generativity. Structural equation modeling revealed that identity balance predicted both intimacy and generativity for the diffuse-avoidant style (negative prediction) and normative style (positive prediction), whereas the informational style provided direct positive prediction of intimacy and generativity. The importance of an informational identity style for psychosocial balance during both early and middle adulthood is discussed.     

Lateral asymmetries of orientation to track control in extrapersonal space

In an initial experiment, subjects were asked to make simple lateral lever responses to left and right verbal and arrow directions with the preferred hand. No asymmetries were found. In two subsequent experiments, subjects guided a track through a left or right turn in one of four orientations under instructions which were direct, compass points, or physical referents, by either a rotary or a discrete control. Asymmetries of direction of turn were observed. Rotary control produced a response bias towards the body midline, but independently of this factor there was a powerful bias towards right turns of track direction in extrapersonal space. Discrimination in the horizontal plane was more difficult than in the vertical plane especially when the instructions were compass points. Within the horizontal plane, together with the bias to right turns of track direction, a bias towards the right of the display was present. The interaction of these factors is believed to underlie reported errors in route finding and direction giving situations.     

A contingent view of reactions to objective pay conditions: interdependence among pay structure characteristics and pay relative to internal and external referents

The authors studied the general proposition that because social comparisons are so central to how people react to pay, the effect of an important pay condition likely depends on a social pay comparison that is relevant to that condition. To investigate this, the authors used actual pay data on more than 2,000 public school teachers across more than 400 school districts and tested whether pay equity perceptions resulted from interactions among objective measures of structural (pay dispersion, entry-level pay, pay range maximum, external competitiveness) and individual (pay relative to internal referents, pay relative to external referents) pay conditions. Cross-level interactions indicated that pay relative to internal referents moderated how pay structure conditions related to pay equity perceptions. Additionally, within-level interactions indicated that the effect of employee standing in the external pay hierarchy depended on where one stood in the internal pay hierarchy; this dynamic emerged both for individual-level measures of current standing and for organization-level measures that suggested future standing.