Source:SISSA

When observing an object, what we see might not be an accurate representation of its actual size. Instead, our perception might be influenced by previously viewed objects – a large object might make the subsequent one seem bigger than it is, and vice versa for a small object.

This visual bias is linked with early visual-evoked brain activity and is driven by the residual information retained by neural populations in our brain’s basic visual analysis levels. In essence, what we see is an ‘average’ our brain creates between what’s happening before our eyes and what has occurred in the past.

Recently published in the Journal of Neuroscience, this research reaffirms an intriguing concept in neuroscience: our perceptions are often distorted representations of the external world, rather than faithful reproductions.

Researchers Michele Fornaciai, Irene Togoli and Domenica Bueti from Scuola internazionale Superiore di Studi Avanzati (SISSA) suggest that this bias arises from a mismatch between our brain’s limited computational resources and the multitude of stimuli bombarding our senses.

This distortion helps our brain find regularities, making the external world more predictable and manageable.

One such perceptual distortion involves seeing similarities between stimuli presented in succession. For example, our judgment of a group of objects’ numerosity may be skewed based on the number of objects we’ve seen before.

The neural mechanisms behind this perceptual bias remain a subject of ongoing investigation.

To study this phenomenon, the SISSA team asked volunteers to watch sequences of simple black-and-white dots on a computer screen, and then estimate their number, size, and display duration.

The scientists observed that perception was indeed influenced by previously viewed images. EEG signals revealed that the occipital cortex, the visual part of the brain, retained traces of past images, and the stronger this trace, the more pronounced the perceptual bias.

These results highlight an essential aspect of perceptual history bias: our brains combine current sensory information with past information, creating an ‘average’ of the past and present images at the earliest stages of visual analysis.

These findings underscore our brain’s role not merely as a mirror of reality, but as a constructor of reality, where our perception is partially based on our expectations and past experiences.

Keywords; Perception, reality