Retinotopic activity in V1 reflects the perceived and not the retinal size of an afterimage

Is the Primary Visual Cortex a Center Stage for the Visual Phenomenology of Object Size?

“…Consistent with previous fMRI studies that examined V1 activation during size perception in the context of optical illusion displays (Murray et al, 2006;Fang et al, 2008) and afterimages (Sperandio et al, 2012), the authors show that their fMRIadaptationparadigmmodulatedV1activityin a manner that mirrored the perceived rather than the retinal image size. This conclusion was based on three key findings.…”

“…Yet, functional magnetic resonance imaging (fMRI) studies in recent years have demonstrated that early sensory structures play a far greater role in size constancy than previously thought. Specifically, fMRI experiments involving optical illusion displays (Murray et al, 2006;Fang et al, 2008) and afterimages (Sperandio et al, 2012) reveal that patterns of activation in the primary visual cortex (V1) more closely reflect the visual experience of an object size than its retinal image size. One view that has been put forth to explain these effects is top-down modulation (Murray et al, 2006;Fang et al, 2008;Sperandio et al, 2012).…”

“…Specifically, fMRI experiments involving optical illusion displays (Murray et al, 2006;Fang et al, 2008) and afterimages (Sperandio et al, 2012) reveal that patterns of activation in the primary visual cortex (V1) more closely reflect the visual experience of an object size than its retinal image size. One view that has been put forth to explain these effects is top-down modulation (Murray et al, 2006;Fang et al, 2008;Sperandio et al, 2012). According to this view, the linear perspective cues in the optical illusion displays providing spatial context in the studies by Murray et al (2006) and Fang et al (2008) In a recent study published in The Journal of Neuroscience, Pooresmaeili et al (2013) examined the role of V1 in size perception using fMRI.…”

“…One view that has been put forth to explain these effects is top-down modulation (Murray et al, 2006;Fang et al, 2008;Sperandio et al, 2012). According to this view, the linear perspective cues in the optical illusion displays providing spatial context in the studies by Murray et al (2006) and Fang et al (2008) In a recent study published in The Journal of Neuroscience, Pooresmaeili et al (2013) examined the role of V1 in size perception using fMRI. The authors argued that their paradigm allowedthemtoexaminelocalresponsesinV1 in a way that is less prone to top-down modulation than the methods used in the previously mentioned size-constancy experiments.…”

Perceptual Organization and Consciousness

“…Subsequent work shows that this was not solely due to larger responses to stimuli perceived as larger and that this effect required participants to attend to the stimulus (Fang, Boyaci, et al 2008). More recently, this effect was further corroborated by the finding that the perceived size of a retinal afterimage is also reflected by V1 activity (Sperandio, Chouinard, et al 2012). Intriguingly, the perceived size of afterimages is also susceptible to contextual size illusions (Sperandio, Lak, et al 2012).…”