Apparent motion perception in patients with paranoid schizophrenia

Abstract

Impaired perceptual inference has been suggested to be at the core of positive symptoms in schizophrenia. Apparent motion (AM) is a visual illusion in which perceptual inference gives rise to the experience of a single object moving back and forth when two spatially separated objects are flashed in alternation. Here, we investigated the strength of AM perception in patients with paranoid schizophrenia. Patients were less susceptible to the illusion as indicated by a lower probability of motion perception at the individual's optimal presentation frequency for AM. In addition, the probability of AM perception was inversely related to delusional conviction in the patient group. These results suggest that schizophrenia may be associated with a reduced susceptibility to visual phenomena that commonly rely on perceptual inference.

What visual illusions teach us about schizophrenia

“…Indeed, schizophrenia resistance to VIs and susceptibility to hallucinations can be considered to result from the same circular inferential process in an ambiguous environment. This assumption has strong support in studies that identified negative correlations between illusion susceptibility and the presence of positive symptoms in healthy (Bressan and Kramer, 2013) and clinical populations (Keane et al, 2013; Sanders et al, 2013). …”

“…(2) Top-down expectations are thought to be primarily responsible for the Apparent motion illusion , in which two stationary stimuli alternatively flickering induce an impression of movement. Resistance to the illusion in schizophrenia patients was notably attributed to their incapacity to correctly use top-down processes in this situation (Sanders et al, 2013). (3) The fact that patients with schizophrenia failed to correct for the inverted Hollow Mask to a more plausible (or predictable) interpretation can also be explained by an underweighting of prior knowledge during perceptual inferences (Schmeider et al, 1996; Schneider et al, 2002; Koethe et al, 2009).…”

A review of abnormalities in the perception of visual illusions in schizophrenia

“…Another low-level integration illusion where there is an apparent resistance is illusory line motion. Both studies identified by this review found that patients were significantly less susceptible to the illusion than healthy controls (Crawford et al, 2010; Sanders et al, 2013). Specifically, Sanders and colleagues (2013) found the magnitude of this illusion to be inversely correlated with Peter’s Delusional Ideation conviction subscale.…”

“…greater resistance to illusion) in SCH compared to controls within a week of admission and within 3rd week. However, 1 week before discharge no apparent differences compared to controls.Illusory line motionCrawford et al, 2010 19 Chronic SCH (4 F, 15 M, 24–48 years)26 HC (9 F, 17 M, 21–56 years)N/AN/AForced choiceMagnitude of the illusion weaker in patients with schizophrenia compared to controlsSanders, de Millas, Heinz, Kathmann, & Sterzer, 2013 34 Paranoid SCH (13 F, 21 M, M = 35 years)34 HC (13 F, 21 M, M = 34.6 years)18.1, 21.5, 75.3N/AForced choiceMagnitude of the illusion weaker in patients with paranoid schizophrenia compared to controlsApparent motion of stimuli was negatively correlated with Peter’s Delusional Ideation (PDI) conviction subscaleRoelof effectChen, McBain, Norton, & Ongur, 2011 33 SCH (15 F, 18 M, M = 20.5 years, 17 SCH, 16 SCH-A)34 HC (17 F, 17 M, M = 15.1 years)15.4, 14.4, (total not reported)N/AForced responseGreater illusionary effects seen in responses of patients with schizophrenia compared to healthy controlsKanizsa squareSpencer & Ghorashi, 2014 17 SCH (1 F, 16 M, M = 43.8)14 HC (2 F, 12 M, M = 43.6)N/AN/AForced choiceNo difference in errors of whether an illusory square was present or not.Keane et al, 2014 75 Patients (46 SCH, 29 SCH-A, 62 % M, M = 46.0 years)18 HC (50 % M, M = 41.1 years)20.1, 18.2, 77.9N/AForced choicePatients were less able to distinguish between illusory and non-illusory conditions however, distractor contours reduced illusion perception similarly to as seen in HC suggesting shape perception not illusory contour difficulties.Hermann gridKantrowitz et al, 2009 38 Chronic SCH/SCH-A ( M = 37.3 years)28 HC ( M = 36.5 years)N/A40.9Forced choiceAt 100 and 50 % levels of contrast, patients were significantly less susceptible to the illusion than controls, but not at 10 or 30 %.Contrast–contrast illusionBarch et al, 2012 153 SCH/SCH-A (62 % M; M = 39.6 years)137 HC (55 % M; M = 36.7 years)N/APositive symptoms = 8.7,Negative symptoms = 7.4, Disorganised symptoms = 5.2Forced choiceReduction in the contrast-contrast effect in SCH compared to healthy controls.Dakin, Carlin, & Hemsley, 2005 15 Chronic SCH20 HCN/AN/AForced choicePatients were less vulnerable to contrast-contrast effect than healthy controls.Yang et al …”

Risk genes, metabolic syndrome and eye tracking deficits in psychiatric diseases

“…Sanders et al [7] seized the suggestion of impaired perceptual inference being at the core of positive SZ symptoms via testing the strength of apparent motion (AM) in 34 patients with paranoid SZ compared to 34 healthy controls. AM is a visual illusion triggering the impression of seeing one object moving back and forth when two spatially separate objects are alternately flashed.…”