The attentional modulation of visual processing dynamics in the human brain

<p>Selective attention is crucial to effectively function in the world around us. We need to select the relevant information from the large amount of sensory input that we receive. The aim of this thesis is to investigate how selective attention affects the processing of visual information in the brain, and how this information is in turn used by the brain to effectively guide behaviour. I aim to separate attention effects from other factors, such as visual short-term memory, decision-making, and temporal expectation. I use multivariate pattern analyses in combination with neuroimaging and time-resolved electrophysiological methods to investigate these questions in both space and time, with a special emphasis on the time-course of attention effects. Together, this thesis aims to increase our understanding of the dynamic attentional modulation on the representation of visual information in the brain.</p> <p>In the first study, I investigated whether attention affects the coding of visual information in the brain, separately from decision-making processes, in both space and time. The results showed that attention affected the processing of visual information, before a decision could be made. In addition, attention affected stimulus coding in frontoparietal cortex and visual cortex, separately from decision-making processes. These results provide evidence that attention can affect the representation of visual information in frontoparietal cortex as well as visual cortex separate from decision-making processes.</p> <p>In the second study, I explored whether attention can affect information processing in the brain when separating out the contribution of target-related processes, such as visual short-term memory and decision-making. In addition, I investigated whether the attention vii effect was modulated by temporal expectation. The results showed stronger coding of attended compared to unattended information, with a similar time-course as established in the first study. This attention effect occurred even when separating out target-related processes, and was not modulated by whether the onset time of the visual stimulus was expected or not. These findings provide insight into the time-course of the effect of attention, separate from target-related processes and temporal expectation.</p> <p>In the third study, I determined whether the coding of attended and unattended information was modulated by the similarity between the attended and unattended information. In addition, I investigated whether the coding of this information was linked to behaviour. The results showed that similarity between the attended and unattended information affected the neural coding of both of these types of information. In addition, the results showed that the coding of the distracting unattended information could bias behaviour. These results provide insight into the time-course of interference between the attended and unattended information affects the coding of this information, and show that this information is used by the brain.</p> <p>Together, these findings provide insight into the time-course of attention effects on the representation of visual information in the brain, separate from other cognitive processes, such as visual short-term memory, decision-making, and temporal expectation. In addition, the representation of distracting information can bias behaviour, providing insight into how this information is used by the brain to shape our behaviour.</p>