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Biomedical subjects

R M Kohl

Publications and source records attributed to R M Kohl.

7 recordsLinked to original sources
PubMed1995

Imaging goal-directed movement.

The main purpose of the present investigation was to determine how Shepard's (1968) second-order isomorphic principle relates to imaging goal-directed movement. Reports of movement times for actual and imaged movements were obtained using Fitts-type tapping tasks. Displays consisted of two different (referential) or two identical (nonreferential) stimulus pairs. In Experiments 1a and 1b, target width and amplitude were manipulated to produce two indexes of difficulty. In Experiments 2a and 2b, the index of difficulty was constant, and biases were created by indicating that movement time increased with decreases in target width or increases in amplitude. In all four experiments, reported movement time reflected Fitts' (1954) law for actual tapping and during early trials for referential imagery. In Experiments 1a and 1b, reported movement times for the two indexes of difficulty were similar for nonreferential imagery and at later trials for referential imagery. In Experiments 2a and 2b, reported movement times reflected the biases for nonreferential imagery and at later trials for referential imagery. The results suggest that propositional knowledge and information processing interact to control movement imagery.

Adult↗
PubMed1992

Alternating actual and imagery practice: preliminary theoretical considerations.

The main purpose of the following experiments was to reexamine the acquisition effects of alternating actual and imagery practice on retention. This was accomplished by making retention comparisons between groups that either alternated actual and imagery practice, alternated actual practice and rest, employed all actual or all imagery practice, or performed an unrelated task (the control) during acquisition. Results from Experiment 1 indicated that the actual practice and the alternating actual and imagery practice groups produced equivalent scores that were greater than the equivalent scores of the imagery practice and alternating actual practice and rest groups. All experimental groups performed better than the control. Because the retention test was identical to the actual practice protocol, practice specificity may have biased the retention relative standings in favor of the actual practice group. Experiment 2 was identical to Experiment 1 except subjects were transferred to a contralateral limb retention test. Results indicated that the alternating actual and imagery practice group produced better retention scores than the equivalent retention scores of the actual practice and imagery practice groups. These three groups produced higher retention scores than the alternating actual practice and rest group, which was better than the control. These results support the notion that alternating actual and imagery practice facilitates motor learning and suggest that practice specificity may be a factor in response imagery experiments. Based on the notion that actual and imagery practice activate shared and unique mechanisms, several hypotheses were offered to explain these results.

Adult↗
PubMed1991

Composition of practice: influence on the retention of motor skills.

The purpose of these experiments was to investigate further the variable practice effect found by Shea and Kohl (1990). Experiment 1 was an initial attempt to determine the locus of the retention benefits demonstrated by subjects provided variable practice experiences. All groups received 20 acquisition blocks consisting of five test trials per block at a target of 150 N. The interval between test trials was either unfilled or filled, with additional trials consisting of the same target force, variable target forces, or practice on an unrelated motor task. The results indicated retention was not incremented (relative to an unfilled interval) by requiring subjects to perform an unrelated motor task in the intertest-trial interval. However, when the interest-trial interval was filled with practice on related motor tasks, retention was significantly improved. Experiment 2 assessed the impact of increasing the number of related motor tasks interpolated between test trials. The results indicated filling the intertest-trial interval with one motor task resulted in large retention benefits relative to an unfilled interval. Further increases in the number of related motor tasks (3) interpolated between test trials resulted in only modest increments to retention. The results were consistent with the elaboration perspective proposed by Shea and Zimny (1983). The elaboration perspective proposes that the simultaneous presence of related items in working memory facilitates interitem elaborative and distinctive processing that ultimately results in retention benefits.

Adult↗
PubMed1990

Specificity and variability of practice.

The specificity of learning principle proposes that motor skills are specific and only superficially resemble other similar skills or variations of the same skill. On the other hand, the variability of practice hypothesis derived from schema theory proposes that experiences with task variations are vital to the development of the memories (schemata) responsible for response production and learning. This paper contrasts these two positions in two experiments aimed at determining the influence of providing variable and/or specific acquisition experiences on the retention of a force production task. The results clearly indicated that acquisition practice with variations of the criterion task leads to better retention than practice on the criterion task alone. This finding is contrary to a strict interpretation of the specificity of learning principle and suggests that paradigms investigating schema notions should be expanded to include potential impacts of variability of practice on tasks experienced during acquisition.

Biofeedback, Psychology↗
PubMed1987

Scaling task complexity along a single dimension.

Time-on-target on pursuit rotor tracking tasks has been shown to decrease for triangle, square, and circle templates, respectively. Since these templates are unrelated geometric shapes they cannot be scaled along a single continuous dimension. For the present study, templates were constructed to be continuously scaled by eccentricity. It was demonstrated that time-on-target on pursuit rotor tracking was a decreasing function of template eccentricity. Also, it was concluded that elliptical templates were preferred over the usual geometric templates because time-on-target relationships among templates can be examined.

Adolescent↗
PubMed1984

Toward a central-peripheralist model of work decrement.

Payne and others, within a Hullian framework, have analytically defined reactive inhibition in terms of a negative drive occurring within the effector system. In strong support, they have demonstrated that the maintenance of work decrement is dependent upon limb, but not task, specificity. However, equally creditable research by Adams allows interpretations of inhibition based on the processing of information. These contrasting arguments are evaluated, and an initial model integrating the two is proposed.

Humans↗