Are We Living in the Past?

Researchers from the University of Aberdeen and the University of California, Berkeley describe a “before undiscovered visual illusion” that helps us smooth out what we see over time in a new report published last month in the journal Science Advances.

We perceive an average of what we saw in the previous 15 seconds, rather than analyzing every single visual image, the authors discuss in a paper published in The Conversation, a website where scientists often discuss their latest findings. As a result, our brain deceives us into believing we are in a stable environment by grouping objects together to make them appear more similar. It’s possible that living ‘in the past’ explains why we don’t notice little changes over time.

This optical illusion of visual stability may take some explaining before it makes intuitive sense. Consider our eyes’ ability to focus on distant objects while maintaining steady in their ability to lock on to objects in their path. Consider what happens to your eyeballs while they’re focused; they have to move all about in order to retain that smooth feeling while focusing on distant objects—much like a gyroscope that stays upright at all times.

Different ideas exist to explain how our eyes and brain collaborate to smooth out what we see. Change blindness (when an input changes but we don’t perceive it) and inattentional blindness (when we fail to see a visual object because our attention is diverted elsewhere) are two examples of reasons that could explain our lack of jitters despite our perception’s kaleidoscope-like disarray. These theories have spawned real-world innovations, such as smartphone video smoothing software. The researchers in this study, however, wanted to learn more about a different idea known as serial dependence.

To put this notion to the test, the researchers created an experiment in which participants saw a steadily shifting image of a face transforming from young to elderly or from old to young. Our brains will notice a lag between the age we perceive the face to be in the shifting picture and the actual age of the face in the picture if we are stuck in the recent past. 

The researchers added increasing intervals of time in the center of the moving image, starting at one second and actually moving up to 15 seconds, while still reporting the same illusory misgauging of the picture’s age, to further examine the specificity of serial reliance. This suggests that our brains can smooth out images as ancient as 15 seconds, and potentially even longer.

Source: https://www.science.org/doi/10.1126/sciadv.abk2480