Perceptual flexibility after frontal or temporal lobectomy.

Using stimuli with ambiguous figure-ground relationships, Ricci and Blundo (1990, Neuropsychologia 28, 1163-1173) demonstrated that patients with frontal-lobe lesions are impaired at shifting perspective. No significant difference between right frontal and left frontal groups was found. To investigate this phenomenon further and to look for a possible lateralization-of-lesion effect, 31 patients who had undergone focal cortical excision for the relief of intractable epilepsy and 10 normal control subjects were tested on an expanded version of the original task. It was found that no subjects had any difficulty recognizing at least one aspect in each of the figures and that only patients with right frontal lesions were significantly impaired in recognizing a second. These results indicate that the right frontal region has a particularly important role in the ability to shift visual perspective.