Logical reasoning in schizotypal personality

It was examined whether psychotic-like personality traits in a sample of 205 college students could predict logical reasoning deficits, akin to those seen in schizophrenia. The participants were tested on their ability to assess the logical validity of premises (Logical Reasoning Task), and completed a multi-dimensional schizotypy inventory (O-LIFE). Low accuracy was associated with increased levels of disorganized schizotypy (‘Cognitive Disorganization’), while elevated errors were associated with increased levels of positive (‘Unusual Experiences’), negative (‘Introvertive Anhedonia’) and impulsive (‘Impulsivity Non-conformity’) schizotypy. Nevertheless, multiple regression analyses revealed that negative schizotypy was retained as the only significant predictor after performance was corrected for random guessing, and the contribution of the average amount of time spent on each premise was controlled. The results suggest that, although most schizotypy dimensions have a detrimental effect on reasoning performance, possibly due to disadvantageous test-taking strategies, negative schizotypy is the most reliable predictor of logical reasoning deficits. It is proposed that social/interpersonal schizotypal traits, like negative symptoms of schizophrenia, are accompanied by deficient executive functions of working memory, which appear to undermine, inter alia, logical reasoning processing.     

Free viewing perceptual asymmetries for judgment of brightness and quantity: dependence on stimulus orientation

Previous research has indicated that normals exhibit strong leftward biases during free-viewing perceptual judgments of brightness and quantity. When participants view two symmetrical objects and they are forced to choose which object appears darker or more numerous, participants usually select the stimulus with the relevant feature on the left side. The present study investigated the possibility that these perceptual asymmetries are dependent on scanning a stimulus horizontally across the midline by administering a task with two rectangular reversed stimuli presented either horizontally or vertically. When the stimuli were presented horizontally (crossing the midline), participants exhibited leftward biases, but these biases disappeared when the stimuli were presented vertically. This result supports the position that free-viewing perceptual asymmetries are dependent on scanning the stimuli across the midline.     

Handedness and depression in university students: a sex by handedness interaction

Previous research has indicated that there is an increased incidence of left-handedness in samples of depressed individuals. We administered the Beck Depression Inventory (BDI) to a sample of 541 undergraduate students. Left-handed males showed significant elevation of BDI scores. It is unlikely that this result is due to decreased right hemisphere activity or sex-role conflicts. However, one possibility is that known differences in male steroid hormones levels between right- and left-handers contributed to this effect. Press     

Rorschach Comprehensive System data for a sample of 506 adult nonpatients from Argentina

This study is composed of 506 nonpatient adults, ages 18 to 65, all from Argentina. The data were gathered by five examiners, who tested most of the participants at their work site. Inclusion and exclusion criteria are described and interrater reliability statistics at the response level are presented along with findings for the Rorschach Comprehensive System (CS; Exner, 1994).