Daniel W. Kee

Lateralized interference of repetitive finger tapping: influence of familial handedness, cognitive load and verbal production

The repetitive finger tapping of 24 right-handed subjects from dextral and sinistral families was evaluated. Subjects tapped with and without concurrent verbal tasks which included reciting a nursery rhyme, reading words (silent vs aloud) and solving anagrams (silent vs aloud). Overall, results indicated that the concurrent verbal tasks interfered more with right-hand tapping than with left-hand tapping. This pattern was more pronounced for familial dextral subjects than familial sinistral subjects. This latter finding was most evident with the complex verbal task of solving anagrams.

Lateralized interference in finger tapping: Assessment of block design activities

Dual task procedures were used to evaluate lateralized processing of block design solutions. Right-handed college students tapped a micro-key alone vs tapped while solving block design problems. Lateralized interference, implicating right-hemisphere processing, was observed when subjects manually completed block designs with their non-tapping band. When manual block manipulation was not required and subjects solved designs mentally, a different laterality pattern suggesting left-hand facilitation in conjunction with right-hand interference in tapping performance was observed. Only the facilitation effect, however, was reliably different from zero.

Chapter 22 Asymmetric Manual Interference as an Indicator of Lateralized Brain Function

Many concurrent tasks interfere more with the activity of one hand than with the activity of the other hand. The existence of this asymmetric manual interference can provide important insights into attention-related processes. Data from right-handed and left-handed subjects indicate that two factors contribute to the direction and magnitude of asymmetric manual interference: hemisphere-specific competition for attentional resources and hand dominance. Accordingly, when the goal is to use asymmetric manual interference to study one of these factors, it is necessary to control for the other. Procedures are outlined that can accomplish this. When these procedures are employed, it is possible to use asymmetric manual interference to study lateralized brain function and to investigate hypotheses about hemisphere-specific processing capacity.

Lateralized interference in finger tapping: Comparisons of rate and variability measures under speed and consistency tapping instructions ☆ ☆☆

Forty right-handed college subjects tapped with and without a verbal task under two instructional conditions (tap as quickly as possible vs. tap as consistently as possible) and two levels of verbal production (silent vs. aloud). The tapping task consisted of the alternate tapping of two keys with the index finger of the left vs. right hands, while the verbal task was anagram solution. Three rate and four variability measures of tapping performance were evaluated in the identification of lateralized interference. The results indicate that reliable lateralized interference, more right-hand than left-hand tapping disruption, was observed only for variability measures under instructions to tap as consistently as possible. Furthermore, only one of these variability measures was sensitive to an increase in lateralized interference produced by verbal production. Because of the limited demonstration of verbal laterality effects with the two-key tapping procedure in this study, conclusions suggest that the simpler manual task of repetitive tapping of one key should be viewed as the method of choice in future dual-task studies.

Multitask analysis of cerebral hemisphere specialization in monozygotic twins discordant for handedness.

This study constitutes a multitask appraisal of cerebral hemisphere specialization with 13 monozygotic (MZ) twin pairs discordant for handedness. Tasks included dichotic listening, finger tapping with concurrent loads, two tachistoscopic visual half-field tests, and a free-vision face test. Overall, MZ twins showed similar performance asymmetries on most tasks. Different asymmetries, however, were observed on the finger tapping with anagram load and visual half-field with chair stimuli. In these instances, asymmetries for left- and right-handed MZ twins were more similar to patterns reported in the literature for left- and right-handed singletons, respectively, than for opposite-handed co-twins.

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.

Lateralized finger-tapping interference produced by block design activities

Dual task procedures were used to examine hemispheric specialization for nonmanual block design activities. College subjects performed a finger-tapping task with each hand; on some trials concurrent WISC block design solutions were required. Patterns of lateralized interference in tapping under dual-task conditions indicated more left- than right-hemispheric involvement for males, while more bilateral involvement was shown for females.

Lateralized dual task interference in left-handers: initial value differences do not affect the outcome.

The study was conducted to clarify factors involved in dual-task finger-tapping interference. Left-handers, as assessed by hand-writing preference and left-hand baseline tapping advantage, tapped both alone and while solving anagrams. Even though the left-hand baseline tapping advantage was experimentally removed on some (adjusted) trials, greater left- than right-hand tapping interference was observed during concurrent task performance. This result coupled with previous findings for right-handed subjects [Kee and Cherry, Neuropsychologia, Vol. 28, pp. 313-316, 1990] indicates that lateralized interference effects are not merely due to initial baseline tapping differences as proposed by Willis and Goodwin [Neuropsychologia, Vol. 25, pp. 719-724, 1987].

Asymmetries in finger-tapping interference produced by mental versus manual rotation of Shepard and Metzler type objects

Two experiments were conducted using dual-task finger-tapping procedures to examine cerebral hemisphere laterization for mental versus manual rotation. Actual three-dimensional block-designs based on Shepard and Metzlers (1971) abstract three-dimensional cubes were constructed. Forty-eight right-handed introductory psychology students participated in each study. The first experiment showed greater right-hand than left-hand interference for mental rotation implicating more left-hemisphere involvement. In contrast, more left-hand than right-hand finger-tapping disruption with manual rotation was observed suggesting more right-hemisphere involvement. A second experiment was conducted to determine if the right-hemisphere involvement found with manual rotation was due to the manual activity of handling and rotating the blocks. Results showed that dual-task interference produced by irrelevant manual rotation combined with mental rotation was not lateralized. Thus, the pattern of results indicate that the manipulospatial processing required in the first experiment was responsible for the asymmetry implicating right-hemisphere involvement.