Fortunately, we live in a world rich in stimuli of all kinds, which have to be processed by our brains. The "problem" is that our capacity to attend to this information is limited, and so we sometimes make mistakes; for example, if we have to attend to two objects with different colors and shapes, we are likely to confuse the characteristics of both and the perceived element is erroneous. This type of error is known as "illusory conjunctions" or, to simplify, "illusions".
In a study carried out by Pablo Rodríguez-San Esteban and Ana Chica (CIMCYC), together with Pedro Paz-Alonso (BCBL), participants were presented with a divided attention task, in which they were asked to attend to two stimuli at the same time and give two different responses, thus overloading the capacity of their attentional systems to provoke these illusions. In addition, participants were inside the MRI scanner to record how their brains functioned while doing the task.
It was found that, in addition to activations in the parietal lobe, an area of the brain that is often associated with these processes, the visual cortex was activated differently when the participants did the task well and when they committed illusions. One of the main differences is that there was an initial peak of activation for illusions that was not found for successes, which could point to fast but unstable processing that is vulnerable to errors. Another relevant finding is that when the task was done correctly the visual cortex was functionally connected to the rest of the brain, whereas in illusions this did not occur and information was only propagated within visual areas.
These results point to the important role played in these perceptual processes not only by parietal regions, something already reported in previous literature, but also by visual areas, especially early in the process. Furthermore, the relevance of the functional connections between both brain regions is demonstrated.
Contact:
Pablo Rodríguez-San Esteban: @email
Full Reference:
Rodríguez-San Esteban, P., Chica, A. B., & Paz-Alonso, P. M. (2022). Functional characterization of correct and incorrect feature integration. Cerebral Cortex. https://doi.org/10.1093/cercor/bhac147