Dottorato in NEUROSCIENZE DEL COMPORTAMENTO

Titolo della tesi: Cognitive components in visual spatial exploration, reading and binary decision tasks: experimental studies in healthy and pathological populations.

The thesis is comprised of three chapters. The first two chapters examine the attentional and perceptual components of spatial exploration and reading, in both healthy and pathological subjects. Chapter three focuses on the speed of processing and decision making in healthy populations. Chapter 1 investigates the possible relationship between the allocentric component of neglect and visual extinction. On the one hand, the understanding of the allocentric component nature is still incomplete. What is known is that it has a less sensitivity to treatment and a worse impact on patient’s life, as compared to the egocentric component. On the other hand, visual extinction is a poorly evaluated phenomenon in clinical practice with neglect patients. This is mainly due to the high number of trials that are necessary for its evaluation. Therefore, the effects of the frequent co-occurrence of extinction and neglect on the outcomes of rehabilitation programs are largely unknown. The Chapter also explores the possible presence of neglect dyslexia, by focusing on a link between reading errors types (omission and substitution) and the specific components of neglect (egocentric and allocentric). Data collection was a lengthy and laborious process. The two years of the Covid-19 pandemic, when access to hospitals and laboratories was banned or highly restricted, were not helpful. Chapters 2 and 3 are written as primary research articles. Chapter 3 has been recently submitted to the Experimental Brain Research journal and is currently under revision. Chapter 2 describes two experiments conducted on normal readers to investigate how crowding modulates the word length effect in peripheral reading. Through the manipulation of size and inter letter spacing of the stimuli, we also evaluate the effect of stimulus spatial extension at different eccentricities on reaction times (RTs) and on the oculomotor pattern. Chapter 3 gives an overview of binary decision-making process and RTs models. It is a follow-up work of my master’s degree thesis. More specifically, the Diffusion Model by Ratcliff (1978) is applied on data from a lexical decision and a gender judgment tasks. The model calculates the relevance of the total RT’s intervenient cognitive components, namely the drift rate, the z value, the boundary separation and the Ter. The study explores the cross-linguistic differences in terms of drift and boundary separation, or response criterion parameter of a group of native Italian (a transparent orthography) and English (an opaque orthography) young speakers using a lexical decision task. The chapter also describes a gender identification study conducted as a control to the previous experiment to confirm that the decision-making differences emerged, were only related to differences in orthographic depth between the two languages.