Denis Raczkowski

Reliability and validity of some handedness questionnaire items.

Abstract A group of college students filled out a handedness questionnaire; a month later they were asked to perform the tasks mentioned on the questionnaire and then to fill out the questionnaire again. Twenty-three items have been scaled for reliability and validity and for the frequency of right hand preference by predominantly left handed people. On these bases, certain items are recommended for inclusion on future handedness questionnaires.

Visual neglect in the tree shrew after interruption of the descending projections of the deep superior colliculus

Abstract Four tree shrews received tegmental lesions aimed at a transection of those fibers from the deep superior colliculus which cross and descend in the predorsal bundle. In two cases the transection appeared complete or nearly so and these animals suffered a profound deficit in attention which resembles “visual neglect” as that term is used in the neurological clinic, as well as the experimental laboratory. In two cases with lesser lesions, the deficit was less severe. While all of the animals showed some defects in tracking, orienting, and following, and while all tended to sit motionless, they all retained the capacity to discriminate patterns and showed other evidence that they had no sensory or motor loss or a defect in emotion, learning, or level of consciousness. It was concluded that neglect is a specific deficit in attention and is the result of transecting efferent descending pathways from the deep layers of superior colliculus. Since the deep superior colliculus receives fibers from the cortex, it was suggested that neglect in man may be caused by some disruption of the deep tectal system which is normally dependent on the cortex.