Two new studies from the Centre for Neuroscience (CNS), Indian Institute of Science (IISc), have explored how closely attention and eye movements are linked, while unveiling how the brain coordinates the two processes.
Attention is a unique phenomenon that allows us to focus on a specific object in our visual world, and ignore distractions. When we pay attention to an object, we tend to gaze towards it. Therefore, scientists have long suspected that attention is tightly coupled to rapid eye movements, called saccades. In fact, even before our eyes move towards an object, our attention focuses on it, allowing us to perceive it more clearly – a well-known phenomenon called pre-saccadic attention, IISc said in a press release.
However, in a new study published in PLOS Biology, the researchers at CNS show that this perceptual advantage is lost when the object changes suddenly, a split second before our gaze falls upon it, making it harder for us to process what changed.
“Our study provides an interesting counterpoint to many previous studies which suggested that pre-saccadic attention is always beneficial,” said Devarajan Sridharan, Associate Professor at CNS and corresponding author of the study.
In the PLOS Biology study, Priyanka Gupta, a PhD student in Sridharan’s lab, trained human volunteers to covertly monitor gratings (line patterns) presented on a screen, without directly looking at them, and to report when one tilted slightly. “Importantly, the participants did this task just before their eyes moved, in the pre-saccadic window. So, we were able to study the relationship between pre-saccadic attention and the detection of changes in the visual environment,” explains Gupta. A tracker was used to monitor their eye movements before, during and after their gaze fell on the object. “To our surprise, participants found it harder to detect the changes in the pre-saccadic window,” Gupta added.
In a follow-up experiment, they made the participants monitor two gratings presented one after the other quickly, again, just before their eyes moved. What the team found was that if the orientation of the second grating suddenly changed during this time, the participants tended to mix up the
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