Reliability in reporting perceptual experience: Behaviour and electrophysiology in hemianopic patients. (May 2019)

• Record Type: Journal Article
• Authors: Mazzi, Chiara; Tagliabue, Chiara Francesca; Mazzeo, Gaetano; Savazzi, Silvia
• Is Part Of: Neuropsychologia. Volume 128(2019)
• Page Start: 119
• Page End: 126
• Publication Date: 2019-05
• Subjects: Perceptual awareness scale -- Hemianopia -- ERPs -- Visual Awareness Negativity -- Late positivity -- Visual awareness; Neuropsychology -- Periodicals; Neurology -- Periodicals; Psychophysiology -- Periodicals; Neuropsychologie -- Périodiques; Neuropsychology; Periodicals; Electronic journals; 616.8
• DOI: 10.1016/j.neuropsychologia.2018.01.017
• Languages: English
• ISSNs: 0028-3932

Abstract

Abstract: Patients with hemianopia can present with the so called blindsight phenomenon: the ability to perform above chance in the absence of acknowledged awareness. Proper awareness reports are, thus, crucial to distinguish pure forms of blindsight from forms of conscious, yet degraded, vision. It has, in fact, been recently shown that 1) dichotomous and graded measures to assess awareness can lead to different behavioural results in patients with hemianopia and that 2) different grades of perceptual clarity show different electrophysiological correlates in healthy participants. Here, in hemianopic patients, we assessed awareness by means of the four-point Perceptual Awareness Scale (PAS) and investigated its neural correlates with Event Related Potentials (ERPs). Results showed that patients, in most of the cases, can rate the clarity of their perceptual experience in a graded manner. Moreover, graded perceptual experiences correlated with the amplitude of deflections in ERPs. These results call for the need to assess perceptual awareness with graded measures and for the importance to use electrophysiological data to correlate behaviour with neural processing. Highlights: Hemianopic patients can grade their phenomenal experience along PAS levels. The amplitude of VAN is modulated by the perceived clarity of the stimulus. LP, although present, does not increase in amplitude as a function of awareness.