Representational pseudoneglect in normals

Abstract

Pseudoneglect in perceptual space is a highly reliable and significant phenomenon (as tested by conventional line bisection tasks)[25, 26]. Much less is known about the existence of pseudoneglect in the representational domain.

Sixty healthy volunteers (30 students, 30 ‘healthy elderly’) were tested on a simple visuo-spatial working memory task. They were asked to study a novel array of ten images presented on a white 590mm x 420mm experiment board for 30 seconds, and to encode the layout as a visual representation. In recall, subjects were requested to report what stimuli they could remember, and where they could remember them. Ten trials were conducted. In five of the trials, subjects were asked to report exactly what they had just seen (condition one). In the remaining five trials they were asked to report from the opposite perspective, requiring a 180o mental rotation of the memorised representation (condition two). The two conditions were requested at random.

An additional case study of a patient with representational neglect (JG) is included as a means to find out the extent to which healthy controls perform exactly as neglect patients. A family study of an individual (Y1) showing gross-transposition is also included, as a means to determine any hereditary factors of this phenomenon. Findings show a striking rightward bias of transposition errors, especially in condition one (double the number of stimuli were transposed towards the right). Age has clear detrimental effects on task performance, with transposers exceeding non-transposers in the healthy elderly group. Four individuals showing representational neglect are documented. All show characteristic behaviours that are analogous with behaviours seen in representational neglect patients.

Future studies need to explore pseudoneglect at depth in the representational domain; addressing statistical significance and hereditary factors. Ultimately, evidence needs to be provided for the true relationship between representational pseudoneglect and representational neglect.