Random number generation in neglect patients reveals enhanced response stereotypy, but no neglect in number space.

Based on interactions between number and space apparent from healthy subjects' randomization attempts we expected random number generation (RNG) to be sensitive for the monitoring of unilateral spatial deficits. Specifically, we predicted patients with left-sided hemineglect to evidence "neglect in number space", i.e. to produce a deficiency in the generation of small, "left-sided" numbers. In RNG of digits from 1 to 6, 19 patients with left-sided neglect generated sequences with a higher redundancy, but as many small numbers as did a matched control group. We discuss possible reasons for the absence of a small-number neglect and emphasize that the observed redundancy was not due to a counting bias, as known from other neurological patients, but to an unspecific imbalance in the use of response alternatives. We speculate that this may be the consequence of disrupted fronto-parietal functions normally serving in the sequential organization and manipulation of items in working memory.