Abstract
People with schizophrenia (SCZ) are impaired in several domains of visual processing, including the discrimination and detection of biological motion. However, the mechanisms underlying SCZ-related biological motion processing deficits are unknown. Moreover, whether these impairments are specific to biological motion or represent a more widespread visual motion processing deficit is unclear. In the current study, three experiments were conducted to investigate the contribution of global coherent motion processing to biological motion perception among patients with SCZ. In Experiments 1 and 2, participants with SCZ (n = 33) and healthy controls (n = 33) were asked to discriminate the direction of motion from upright and inverted point-light walkers in the presence and absence of a noise mask. Additionally, participants discriminated the direction of non-biological global coherent motion. In Experiment 3, participants discriminated the direction of motion from upright scrambled walkers (which contained only local motion information) and upright random position walkers (which contained only global form information). Consistent with previous research, results from Experiment 1 and 2 showed that people with SCZ exhibited deficits in the direction discrimination of point-light walkers; however, this impairment was accounted for by decreased performance in the coherent motion control task. Furthermore, results from Experiment 3 demonstrated similar performance in the discrimination of scrambled and random position point-light walkers.
Highlights
Since Johansson (1973) first introduced point-light walkers as an experimental tool for examining the perception of human motion, many studies have demonstrated the sensitivity of the human visual system with respect to detecting and perceiving biological motion
Bonferroni adjusted paired t-tests revealed that participants performed significantly more accurately in the upright condition compared to the inverted condition (t(263) = 3.41, p < 0.001)
GENERAL DISCUSSION The present study examined the effects of SCZ on the perception of biological motion
Summary
Since Johansson (1973) first introduced point-light walkers as an experimental tool for examining the perception of human motion, many studies have demonstrated the sensitivity of the human visual system with respect to detecting and perceiving biological motion. Individuals with schizophrenia (SCZ) exhibit deficits in several aspects of visual motion processing including speed discrimination (Chen et al, 1999; Clementz et al, 2007) and the perception of coherent global motion (Stuve et al, 1997; Chen et al, 2003). This population exhibits deficits in their ability to recognize and interpret social stimuli (Bigelow et al, 2006; Baas et al, 2008) or detect emotions from affective facial expressions (Edwards et al, 2001; Kohler et al, 2003; Johnston et al, 2006; Monkul et al, 2007). Kim et al (2011) found that people with SCZ were less able to detect and discriminate biological motion on tasks that included a noise mask and the perturbation of kinematic information, respectively
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