Dissociation Between Physical And Mental Number Line Bisection In Schizophrenic Patients

Objective In patients with schizophrenia has been verified the existence of attention disorder. To further confirm the existence of unilateral spatial attention disorder in patients with schizophrenia by physical line bisection test. To explore whether there was number spacial representaional disorder in schizophrenic patients through mental number line bisection test. Through the above two tests in patients with schizophrenia to explore the existence of dissociation of processing between physical line and mental number line.Method Test subjects were thirty schizophrenic patients and thirty matched healthy controls. In the physical line bisection tests, two groups of subjects were asked to mark the mid-point of 4-20cm length of line segments to observe the offset and offset rate. In the mental nuber line bisection tests, paticipants heard two numbers with fixed number intervals. The size of the interval could be three (for example, 2-4), five (for example, 1-5), seven or nine. All participants were asked to answer the midpoint number without making calculations. Calculated the deviation values and rates.Result In the physical line bisection test,when the length of lines were 4 cm,6,10,12,14,16,18 and 20 cm, the mean deviations of the schizophrenic patients were higher than control group; the differences were significant(P<0.01).In the number line bisection test, when the interval sizes of numbers were 3, 5, 7 or 9,the mean deviations of schizophrenic patients of antrorse presentation were not significant difference with control group(P>0.05).No significant difference was found contrasted with control group, When the interval sizes of numbers were reverse presentation(P>0.05). When numbers were tactic presentation and reverse presentation, the difference was not obvious(P>0.05).Conclusions Schizophrenic patients showed a significant leftward bias in the physical line bisection test, confirming the existence of unilateral spatial attention disorder. In the number bisetion test, no significant deviation was found contrasted with control group. The results suggested that schizophrenic patients are associated with a deficit of attention, not associated with a deficit of representation of number space. Combining these two experiments, we found leftword deviation in the bisection of numeric and physical intervals was doubly dissociated. It suggested there may were two different neural mechanisms between physical line and mental number line processing.