Appearance and disappearance of unilateral spatial neglect for an object: influence of attention-attracting...

We reported a dramatic phenomenon of appearance and disappearance of left unilateral spatial neglect for the same single object. In experiment 1, four patients with mild neglect who copied a single flower satisfactorily showed left neglect in copying of the same flower when it was accompanied with some peripheral stimuli. In experiment 2, we included three additional conditions to determine the stimulus component crucial for left neglect of the flower: a flower with a stem and a flower with either right or left peripheral stimuli were also used for copying. Overall results showed that neglect was most evident for the flower with the right peripheral stimuli. On the other hand, the presence of left stimuli provoked less severe neglect of the flower, which was as mild as that in the single flower condition. The results were explained in terms of an attentional mechanism underlying unilateral spatial neglect. When copying the flower with peripheral stimuli on both sides or on the right side, the stimuli on the right side might attract the patient's attention. Consequently, he exhibited left neglect on the central flower. On the other hand, neglect was less evident in the other conditions, since the figures did not include such attention-attracting stimuli on the right side.