Improvement of a figure copying deficit during subsensory galvanic vestibular stimulation

We describe the effects of galvanic vestibular stimulation (GVS) on an individual who, following right hemisphere stroke, is unable to copy figures accurately. His copies contain most of the constituent elements, but are poorly integrated and drawn in a seemingly haphazard manner. To test whether GVS could help overcome these difficulties, we administered the Rey-Osterrieth complex figure copy task while manipulating both the presence and laterality of the galvanic signal. The signal was applied at a level that was too low to elicit sensation which ensured that the individual was unaware of either when or on what side he was being stimulated. Relative to a sham condition, two consecutive blocks of GVS increased both the accuracy with which the main configural elements of the figure were reconstructed, and there was some, albeit less consistent evidence, that these were drawn in a more wholistic as opposed to piecemeal manner. Improvement was not reliant on the polarity of the stimulating electrodes. These results suggest that GVS can help overcome difficulties in the perception and/or reconstruction of hierarchical visual form, and thereby uncover a new link between vestibular information processing and visual task performance.     

Theoretical and methodological analysis of partial knowledge

A theory of partial knowledge is proposed as an explanation of cognitive development, and methods are described for testing the theory. The theory consists of three structure-process pairs, each of which postulates a type of cognitive structure and a developmental process specific to that type. In restricted knowledge, a unitary algorithm is the cognitive structure, and amendment is the developmental process. In variable sampling, a structure of unitary substitutes is paired with a process of selection. In variable integration, modular components are paired with self-monitoring. Methods for testing the theory form a sequence of mathematical models. The first model in the sequence, called a model of double assessment, is described both verbally and mathematically. Other models in the sequence are described verbally with reference to other articles for the formal mathematics. Also described are some nonmathematical methods to be used as sequels to the double assessment model.     

Book reviews

Paul Ricoeur. Freud and Philosophy: An Essay On Interpretation (trans. Denis Savage). New Haven: Yale University Press, 1970. Pp. 1–551. Indexed. $15.00.

Keith Campbell. Body and Mind. Garden City, N.Y.: Doubleday, 1970. Pp. vi, 150. Indexed. $1.45 (paper).

D. J. O'Connor. Free Will. Garden City, N.Y.: Doubleday Anchor Books, 1971. Pp. 1–150. Indexed. $1.45.

Dwight van de Vate, Jr. (ed.). Persons, Privacy, and Feeling: Essays in the Philosophy of Mind. Memphis: Memphis State University Press, 1970. Pp. vii, 140. Indexed. $5.00.