Contribution of coherent motion to the perception of biological motion among persons with Schizophrenia

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.

Specific vulnerability of face perception to noise: A similar effect in schizophrenia patients and healthy individuals

“…First, in schizophrenia, high levels of internal noise in the face processing system have been suggested (Spencer et al, 2013). According to this suggestion, a smaller effect of external noise on face perception would be predicted for patients as their face processing system is presumably noisy.…”

“…Noise-filtering is essential for the processing of perceptual information including faces, and appears to be implicated in various aspects of deficient perceptual processing in schizophrenia (Chen et al, 2014; Kim et al, 2013; Chen et al, 2008). A recent study proposed heightened noise levels as a mechanism underlying abnormal facial processing in schizophrenia (Spencer et al, 2013). The premise of this empirically- and computationally-inspired proposal is that noise within the facial processing system is heightened in this psychiatric disorder and, as a result, the reduced signal-to-noise ratio degrades patients’ capacity in face perception.…”

Individual differences in the perception of biological motion and fragmented figures are not correlated

“…When animated, the structured motions of the dots create the immediate, compelling impression of a body engaged in a specific activity (e.g., running), with sufficient fidelity to convey not only the type of activity but also the sex and emotional state of the actor (see review by Blake and Shiffrar, 2007). Biological motion portrayed by PL animation has been widely used in recent years to study dynamic perceptual organization in children (Pavlova et al, 2001; Friere et al, 2006), young adults (Hiris, 2007) and the elderly (Norman et al, 2004; Billino et al, 2008; Pilz et al, 2010), as well as in clinical populations including people with autism (Moore et al, 1997; Blake et al, 2003; Kaiser and Shiffrar, 2009; McKay et al, 2012; Nackaerts et al, 2012), prosopagnosia (Lange et al, 2009), schizophrenia (Kim et al, 2005, 2011; Spencer et al, 2013), and brain damage (Cowey and Vaina, 2000; Pavlova et al, 2003). …”

“…Finally, perceptual results from clinical neuropsychological studies hint at a possible linkage between the two forms of grouping. Specifically, one study shows that schizophrenic patients have trouble recognizing objects portrayed as fragmented figures (Doniger et al, 2001b) and several other studies have found that patients diagnosed with schizophrenia exhibit deficits in biological motion perception (Kim et al, 2005, 2011; Spencer et al, 2013). …”

Biological Motion

“…Difficulties with other visual tasks, such as global motion perception, can also occur, arguing for the presence of a more generalized visual processing deficit (Brittain, Ffytche, McKendrick, & Surguladze, 2010;Kim, Norton, McBain, Ongur, & Chen, 2013;Spencer, Sekuler, Bennett, & Christensen, 2013). Schizophrenia patients have difficulties judging the direction of, or presence of, point-light walkers; however, these impairments do not occur in isolation.…”