Laterality, hand preference, and human spatial ability.

6 left-handed females scored significantly below 60 right-handed females on a test of spatial visualization (p less than .005). 13 left-handed males showed a higher mean score than 33 right-handed males on the spatial test, although this difference was not statistically significant. These results are consistent with the hypothesis that the left cerebral hemisphere is of greater relative importance to spatial functioning in females than males.     

A performance measure of the degree of hand preference

The present paper describes a performance method for determining hand preference. The task requires participants to reach into different regions of hemispace to perform various actions (point, pick up, toss, sweep, and position) with a dowel located at each position. In accordance with the participants' hand preference as measured by the Waterloo Handedness Questionnaire, the preferred hand was used more frequently on the various performance tasks. The distribution of hand use in working space indicates that preferred hand use was almost exclusive for actions carried out in ipsilateral hemispace, while it is used only moderately for actions in contralateral hemispace, revealing that this hand is used throughout a wider range of extrapersonal space than the nonpreferred hand. These trends were observed across all of the performance tasks, suggesting that task complexity did not affect the frequency of preferred hand use either overall or, more specifically, in right hemispace, as was predicted. This finding is inconsistent with empirical work on questionnaires indicating that verbal reports of preferred hand use increase for more complex tasks (e.g., Steenhuis & Bryden, 1988). As well, performance on the preferential reaching task correlated significantly with hand preference as measured on the Waterloo Handedness Questionnaire (Bryden, 1977), unlike the other performance measure examined, indicating that the preferential reaching task is sensitive to differences in the degree of hand preference.     

A developmental analysis of the relationship between hand preference and performance: II. A performance-based method of measuring hand preference in children

The present study describes a performance-based method of measuring hand preference in children. Three aspects of handedness were considered to be important in developing the paradigm (a) overall hand preference across a number of tasks, (b) consistency of hand use and, (c) the use of the preferred hand in a bimanual task. The new paradigm, termed the WatHand Box Test (WBT), requires participants to perform a variety of unimanual tasks such as, using a hammer, tossing a ball, and opening a lock with a key. To determine the validity of the WBT and examine the developmental trends in hand preference, eighty right-handed children and adults (ages 3-4, 6-7, 9-10, and 18-24 years) performed the WBT. First, the WBT was found to correlate significantly with scores on a standard hand preference questionnaire for the adults. As well, significant developmental trends were noted in hand preference as measured by the WBT. Most specifically, three- and four-year-olds had significantly lower scores on the WBT indicating a less stable pattern of hand preference than in the other three age groups.     

Strength of hand preference and dual task performance by common marmosets

Study of avian and piscine species has shown that animals with stronger lateralization of the brain are able to perform two tasks presented simultaneously better than can animals with weaker lateralization. We investigated whether this might apply also to primates by testing common marmosets to see whether there is a relationship between the strength of hand preference, as an indicator of strength of brain lateralization, and the ability to carry out two tasks simultaneously. A model predator was introduced into the testing room while the marmoset was foraging. Marmosets with stronger hand preferences detected the ‘predator’ after shorter latency than those with weaker hand preferences. Furthermore, the marmosets with stronger hand preferences produced more mobbing (tsik) vocalizations when they reacted to the predators than did those with weaker hand preferences. There was no such association between hand preference and either latency to respond to the predator or mobbing reaction when the marmosets were not foraging at the time the predator was introduced. Hence, strength of lateralization is associated with the ability to perform foraging and predator detection simultaneously. These results are discussed with reference to the evolution of brain lateralization.     

Postural stability and hand preference as constraints on one-handed catching performance in children

Effects of postural state and hand preference as constraints on 1-handed catching performance were investigated in different ability groups of children aged 9-10 years. On the basis of pretest data, the authors classified 48 participants into groups of good, intermediate, and poor catchers (n = 16 in each) and asked them to perform 1-handed catches with their preferred and nonpreferred hands while standing and sitting. The good catchers' performance was not affected by the imposed postural constraints but did improve when they used the preferred hand. A similar effect of hand preference was evident in the intermediate and poor catchers, but there was also an effect of postural constraint. Independent of hand preference, intermediate catchers' performance while seated improved significantly compared with that during standing. For poor catchers, there was an interaction between hand preference and posture; significant improvement was evident only when they used the preferred hand in the sitting condition. The finding that manipulation of posture and hand preference affected performance outcomes indicates that perceptual skill is not the only influence on catching performance in children. Manipulation of those key constraints may facilitate the acquisition of catching skill, but more research is needed to determine the permanence of those effects.     

Multiple spatial correspondence effects on dual-task performance

Three dual-task experiments were conducted to examine whether the underadditive interaction of the Simon effect and stimulus onset asynchrony (SOA) on Task 2 performance is due to decay. The experiments tested whether the reverse Simon effect obtained with an incompatible stimulus-response (S-R) mapping would show an overadditive interaction with SOA, as predicted by R. De Jong, C.-C. Liang, and E. Lauber's (1994) dual-process model. Tone or letter identification tasks with vocal or keypress responses were used as Task 1. Task 2 was keypresses to arrow direction (or letter identity in Experiment 1). For all experiments, the normal Simon effect showed an underadditive interaction with SOA, but the reverse Simon effect did not show an overadditive interaction. The results imply that the dual-process model is not applicable to the dual-task context. Multiple correspondence effects across tasks implicate an explanation in terms of automatic S-R translation.     

A developmental analysis of the relationship between hand preference and performance: I. Preferential reaching into hemispace

The present study describes a developmental performance measure of hand preference that considers task complexity and position in hemispace. Eighty right-handed children and adults (ages 3-4, 6-7, 9-10, 18-24) were observed for hand selection responses to 2 unimanual tasks (simple vs complex) across positions in hemispace. Results revealed an age-related trend in the tendency to use the preferred hand in right and left hemispace. While the adult's and 3- to 4-year-old's preferred hand use decreased as they moved into left hemispace, children between the ages of 6 and 10 years tended to use their preferred hands consistently throughout both regions of hemispace. The relationship between hand preference and skilled, cost-efficient performance throughout development are discussed.     

Consistency of hand preference: predictions to intelligence and school achievement.

Gottfried and Bathurst (1983) reported that hand preference consistency measured over time during infancy and early childhood predicts intellectual precocity for females, but not for males. In the present study longitudinal assessments of children previously classified by Gottfried and Bathurst as consistent or nonconsistent in cross-time hand preference were conducted during middle childhood (ages 5 to 9). Findings show that (a) early measurement of hand preference consistency for females predicts school-age intellectual precocity, (b) the locus of the difference between consistent vs. nonconsistent females is in verbal intelligence, and (c) the precocity of the consistent females was also revealed on tests of school achievement, particularly tests of reading and mathematics.     

The effects of elimination of hand gestures and of verbal codability on speech performance

Subjects were required to describe line drawings of two-dimensional shapes at two levels of verbal codability, with and without using hand gestures. Elimination of gesture affected speech performance by changing the semantic content of utterances and the proportion of speaking time spent pausing; numbers of words, numbers of pauses, mean pause length and semantic content were found to be related to the verbal codability of the stimulus material; and the number of hesitations was related to both gesture and level of codability.     

Behavioral asymmetries of psychomotor performance in rhesus monkeys (Macaca mulatta): a dissociation between hand preference and skill.

Hand preferences were recorded for 35 rhesus monkeys (Macaca mulatta) as they manipulated a joystick in response to 2 computerized tasks. These preferences were then used to contrast 8 left- and 10 right-handed subjects on performance measures of hand skill. Individual hand preferences were found, but no significant population asymmetry was observed across the sample. However, the performance data reveal substantial benefits of right-handedness for joystick manipulation, as this group of monkeys mastered the 2 psychomotor tasks significantly faster than did their left-handed counterparts. The data support earlier reports of a right-hand advantage for joystick manipulation and also support the importance of distinguishing between hand preference and manual performance in research on functional asymmetries.     

The effects of temporal-precision and time-minimization constraints on the spatial and temporal accuracy of aimed hand movements

Discrete aimed hand movements, made by subjects given temporal-accuracy and time-minimization task instructions, were compared. Movements in the temporal-accuracy task were made to a point target with a goal movement time of 400 ms. A circular target then was manufactured that incorporated the measured spatial errors from the temporal-accuracy task, and subjects attempted to contact the target with a minimum movement time and without missing the circular target (time-minimization task instructions). This procedure resulted in equal movement amplitude and approximately equal spatial accuracy for the two task instructions. Movements under the time-minimization instructions were completed rapidly (M = 307 ms) without target misses, and tended to be made up of two submovements. In contrast, movements under temporal-accuracy instructions were made more slowly (M = 397 ms), matching the goal movement time, and were typically characterized by a single submovement. These data support the hypothesis that movement times, at a fixed movement amplitude versus target width ratio, decrease as the number of submovements increases, and that movements produced under temporal-accuracy and time-minimization have different control characteristics. These control differences are related to the linear and logarithmic speed-accuracy relations observed for temporal-accuracy and time-minimization tasks, respectively.     

Writing hand posture and four indexes of lateral preference

The relationship between writing hand posture and lateral preference for hand, foot, eye, and ear was examined in a sample of 3709 college undergraduates. A markedly different pattern of lateral preferences was observed in left-handed males and females as a function of hand posture. Left-handed male inverters displayed a tendency toward more leftward lateral preferences in all four indexes; while it was found that hand inversion during writing in left-handed females reflected, if anything, a tendency toward more rightward lateral preferences.     

Exposure effects on music preference and recognition

In three experiments, the effects of exposure to melodies on their subsequent liking and recognition were explored. In each experiment, the subjects first listened to a set of familiar and unfamiliar melodies in a study phase. In the subsequent test phase, the melodies were repeated, along with a set of distractors matched in familiarity. Half the subjects were required to rate their liking of each melody, and half had to identify the melodies they had heard earlier in the study phase. Repetition of the studied melodies was found to increase liking of the unfamiliar melodies in the affect task and to be best for detection of familiar melodies in the recognition task (Experiments 1, 2, and 3). These memory effects were found to fade at different time delays between study and test in the affect and recognition tasks, with the latter leading to the most persistent effects (Experiment 2). Both study-to-test changes in melody timbre and manipulation of study tasks had a marked impact on recognition and little influence on liking judgments (Experiment 3). Thus, all manipulated variables were found to dissociate the memory effects in the two tasks. The results are consistent with the view that memory effects in the affect and recognition tasks pertain to the implicit and explicit forms of memory, respectively. Part of the results are, however, at variance with the literature on implicit and explicit memory in the auditory domain. Attribution of these differences to the use of musical material is discussed.     

Some effects of sex-linked clothing and gender schema on the stereotyping of infants

Two predictions were evaluated: first, that given minimal information about an infant, individuals would use sex-related cues (i.e., clothing) to categorize, evaluate, and make attributions about the infant, and second, that gender schematic individuals would be more likely than gender aschematic individuals to use such sex-related cues. On the basis of the Bem Sex Role Inventory, American college students were classified as either gender schematic (masculine or feminine) or gender aschematic (undifferentiated or androgynous). The students categorized, evaluated, and made trait attributions about an infant dressed in male, female, or ambiguous clothing. Both gender schematic and gender aschematic individuals relied on sex-related cues in their perceptions of the infant.     

Development of hand preference in the Colorado Adoption Project

A longitudinal study of the development of hand preference in 152 adopted and 120 nonadopted (control) infants measured in natural behavioral situations at both 12 and 24 mo. of age is reported. Significant developmental trends were observed for both increasing strength and direction of handedness. Less than 10% of the infants exhibited a clear preference at 12 mo. of age, whereas about 30% were lateralized at 24 mo., with more boys than girls being left-handed. In contrast, over 90% of the parents of these children (both biological and adoptive parents of the adopted children and parents of the nonadopted children) were lateralized. Perhaps because so few infants were lateralized at either age, parent-offspring resemblances were inconsistent and the number of significant parent/child correlations was about that expected on the basis of chance alone.     

Posture and target location effects on manual preference

Twenty-nine right-handed participants made unimanual movements to 5 target locations while standing and while balancing on a rocker platform. Manual preference was affected by target location (p < .001; manual preference tended to be concordant with target hemispace) and posture (p < .05; responses from the rocker platform were associated with a lower level of right-hand responding). A location by posture interaction (p < .05) indicated that the effect of posture was present only for targets in left hemispace; the right hand was used less frequently in the rocker condition than simple standing. Manual preference is viewed as a process of response selection motivated by an effort to minimize neural processing and mechanical costs.     

Independence of response force and reinforcement rate on concurrent variable-interval schedule performance

Five pigeons were trained over 43 experimental conditions on a variety of concurrent variable-interval schedules on which the forces required on the response keys were varied. The results were well described by the generalized matching law with log reinforcement ratios and log force ratios exerting independent (noninteractive) effects on preference. A further analysis using the Akaike criterion, an information-theoretic measure of the efficiency of a model, showed that overall reinforcement rate and overall force requirement did not affect preference. Unlike reinforcement rate changes, force requirement increases did not change the response rate on the alternate key, and an extension of Herrnstein's absolute response rate function for force variation on a single variable-interval schedule is suggested.     

The spatial proximity hypothesis of the hand advantage in spatial precuing tasks : A short note concerning discrepant criterion effects

Within the context of the spatial precuing paradigm a consistent finding is that with the hands placed adjacently precuing of two fingers on the same hand results in faster discrete finger responses than precuing of two fingers on different hands. This phenomenon is known as the ‘hand advantage’. Both Miller (1982) and Reeve and Proctor (1984) considered, and rejected, the ‘spatial proximity’ hypothesis as a possible perceptual explanation of the hand advantage. However, data reported by Miller (1982) and Reeve and Proctor (1984) to discount the spatial proximity hypothesis showed a puzzling inconsistency which weakened the strength of the rejection. In this article I address this inconsistency theoretically and experimentally. I conclude that its origin lies in differential operationalizations of the concept ‘preparation effect’. This conclusion justifies rejection of the spatial proximity hypothesis.