A Comparison of Selected Behaviors of Identical Twins,One Blind from Birth

The purpose of this study was to compare differences in mental-emotional, fine perceptual-motor and gross motor behaviors of a set of 13 year-old identical twins, one of whom was blind from birth. In general, the blind twin was superior in performances where total body involvements were minimal and fine manipulative movements of the hands and/or fingers were stressed. The blind twin also appeared to be more well-adjusted emotionally than the sighted twin.     

The development of hand preference in children: The effect of task demands and links with manual dexterity

Lateralisation of hand preference and manual dexterity are known to develop over childhood, while in adulthood strength of hand preference has been shown to interact with extrinsic task demands. Some evidence exists to suggest that strength of hand preference and motor skill may be related. In the current study a handedness inventory, midline crossing (QHP) and peg-moving tasks were used to investigate: (1) the development of hand preference between 4 and 11 years; (2) whether extrinsic task demands affect strength of hand preference, and (3) whether strength of hand preference was associated with manual dexterity. Younger children (4–5 years) showed weak hand preference in comparison to older children (8–11 years), and extrinsic task demands influenced willingness to cross the body’s midline with the preferred hand. Age and peg-moving speed were associated with midline crossing in certain task conditions. Overall, results suggest a coupling between manual dexterity and brain maturation in typical development.     

Improvement in children’s fine motor skills following a computerized typing intervention

Children spend a large proportion of their school day engaged in tasks that require manual dexterity. If children experience difficulties with their manual dexterity skills it can have a consequential effect on their academic achievement. The first aim of this paper was to explore whether an online interactive typing intervention could improve children’s scores on a standardised measure of manual dexterity. The second aim was to implement a serial reaction time tapping task as an index of children's finger movement learning, and to see whether performance on this task would improve after the intervention. Seventy-eight typically developing children aged between 8 and 10 were tested at their school on the pre-intervention Movement Assessment Battery for Children (2nd edition; MABC-2) and tapping tasks. Twenty-eight of these children volunteered to be randomly allocated to the intervention or control group. Children in the intervention group had a choice of two online games to play at home over a period of four weeks, while the children in the control group were not given these games to play. The intervention and control groups were then re-tested on the MABC-2 manual dexterity and the tapping task. Children in the intervention group significantly improved their manual dexterity scores in the MABC-2 compared to the control group. On average, all children learnt the tapping sequence, however, there were no group differences and no effect of the intervention on the tapping task. These results have important implications for implementing a freely available, easy to administer, fun and interactive intervention to help children improve their manual dexterity skills.     

Empathizing, systemizing and finger length ratio in a Swedish sample

von Horn, A., Bäckman, L., Davidsson, T. & Hansen, S. (2010). Empathizing, systemizing and finger length ratio in a Swedish sample. Scandinavian Journal of Psychology, 51, 31–37.
The Empathy- and Systemizing Quotients (EQ and SQ, respectively; Baron-Cohen, 2003 ) were determined in a Swedish sample consisting mainly of university undergraduates. Females had significantly higher EQ than males, who in turn scored higher on the SQ inventory. Gender explained 12–14% of the variation. Males were strikingly overrepresented in the group defined by a high SQ/low EQ profile or by a large SQ – EQ difference; females dominated among people with a low SQ/high EQ profile or by a large EQ – SQ difference. Students majoring in the natural sciences had higher SQs than psychology majors, but in both groups the gender difference in SQ and EQ was strong. For each participant a weighted composite score was generated by multivariate processing of the EQ and SQ data (Partial Least Square Discriminant Analysis). These scores were associated in a sex-linked fashion to a biometric measure reflecting prenatal testosterone exposure, i.e. the ratio between index (2D)- and ring (4D) finger lengths. In males a high (female-typical) 2D:4D ratio predicted an enhanced tendency to empathize and a reduced tendency to systemize; in women, by contrast, the 2D:4D ratio was unrelated to these traits. The present research confirms earlier work of a gender difference in EQ and SQ. The difference appears robust as it appears as large in Sweden (a country with high cultural gender-equality) as in countries with considerably lower gender-equality.     

Force Increase in a Repetitive Motor Task Inducing Motor Fatigue

To evaluate task induced motor fatigue in a well-established finger tapping task, we analyzed tapping parameters and included the time course of measures of force. We hypothesized that a decline in tapping force would reflect task induced motor fatigue, defined by a lengthening of inter-tap intervals (ITI). A secondary aim was to investigate the reliability of tapping data acquisition with the force sensor. Results show that, as expected, tapping speed decreased linearly over time, due to both an increase of ITI and tap duration. In contrast, tapping force increased non-linearly over time and was uncorrelated to changes in tapping speed. Force data could serve as a measure to characterize task induced motor fatigue. Force sensors can assess a decline in tapping speed as well as an independent increase of tapping force. We argue that the increase of force reflects central compensation, i.e. perception of fatigue, due to an increase in task effort and difficulty.     

Dynamic Visual Acuity and Performance in a Catching Task

Each of 30 Ss was given tests of dynamic and static visual acuity and then participated in a ball-catching task. Performance in the latter task was an inverted U-shaped function of duration of the occluded period, the time between the termination of the 80-msec. viewing period and the estimated onset of the “latency period” (the point in time at which the ball could no longer serve to cue Ss response). Dynamic and static visual acuity scores were not significantly correlated but, with static visual acuity partialled out, dynamic visual acuity and catching performance were significantly correlated.     

Analysis and treatment of finger sucking

We analyzed and treated the finger sucking of 2 developmentally typical children aged 7 and 10 years. The functional analysis revealed that the finger sucking of both children was exhibited primarily during alone conditions, suggesting that the behavior was maintained by automatic reinforcement. An extended analysis provided support for this hypothesis and demonstrated that attenuation of stimulation produced by the finger sucking resulted in behavior reductions for both children. Treatment consisted of having each child wear a glove on the relevant hand during periods when he or she was alone. Use of the glove produced zero levels of finger sucking for 1 participant, whereas only moderate reductions were obtained for the other. Subsequently, an awareness enhancement device was used that produced an immediate reduction in finger sucking.     

High working memory capacity favours the use of finger counting in six-year-old children

In this study, we show that 6-year-old children with high working memory capacity are more likely to use their fingers in an addition task than children with lower capacity. Moreover and as attested by a strong correlation between finger counting and accuracy in the arithmetic task, finger counting appears to be a very efficient strategy. Therefore, discovering the finger counting strategy seems to require a large amount of working memory resources, which could lack in low-span children. Furthermore, when children with low working memory capacities use their fingers to solve addition problems, they more often use the laborious counting-all strategy than children with higher capacities who use more elaborated procedures such as the Min strategy. Consequently, we suggest that explicit teaching of finger counting during the first years of schooling should be promoted because it could help less gifted children to overcome their difficulties in arithmetic.     

Impact of Handedness Consistency on Bimanual and Unimanual Continuous Movements

Bimanual coordination is an essential human function requiring efficient interhemispheric communication to produce coordinated movements. Previous research suggests a “bimanual advantage” phenomenon, where completing synchronized bimanual tasks results in less variability than unimanual tasks. Additionally, of hand dominance has been shown to influence coordinated performance. The present study examined the bimanual advantage in individuals with consistent and inconsistent handedness. It was predicted that participants with consistent handedness would not display a bimanual advantage unlike those with inconsistent handedness. Fifty-six young adults completed a finger-tapping paradigm in five conditions: unimanual tapping with either left or right hand, in-phase bimanual tapping, and out-of phase bimanual tapping led by either left or right hand. Results were not consistent with the hypothesis that participants with consistent handedness displayed the “bimanual advantage”. However, the “bimanual advantage” was not evident for the inconsistent handers when the temporal consistency was measured with either the left or right hand only. Overall, the “bimanual advantage” may be dependent upon consistency of hand preference, as well as the direction of hand dominance.