Abstract
The flash-lag effect (FLE) is a prime example of the perceptual problem of time representation. The effect appears to be a temporal perceptual violation of simultaneity that occurs whenever a flash (i.e., sudden and brief) stimulus happens to be physically aligned in space and time with a constantly moving object. This study aims to contribute to the FLE phenomenon by focusing on attention (i.e., as indexed by pupil dilation) and hemispheric specialization (i.e., as indexed by visual hemifields’ differences). The main purposes of this thesis were: 1) To study how visual processing deals with motion interpolation. 2) To investigate whether pupillary responses and eye movements can index mental effort during the FLE task. 3) To investigate or confirm functional asymmetries (e.g., Strong et al., 2019) across left (LVF) and right visual fields (RVF) in terms of motion stimuli processing. Statistical analysis on performance and the effect of asynchrony of motion and flash replicated the classic effect. In addition, they showed interesting differences across visual fields, reaching a significant advantage in the LVF than in RVF in response time and a marginal, non-significant, effect in accuracy. Further, results showed that pupillary responses can index mental effort and hemispheric differences since participants had a tendency to larger pupils in the LVF compared to RVF. Moreover, contrary to previous studies, which claimed that the FLE is not affected by attentional deployment, our study suggests that participants are more engaged with attention (i.e., larger pupils) in the LVF. In addition, results provide a visual field and lag interaction for response time: participants were more accurate, and faster.