Hey, Look at That! New Study Shows Saliency is Only Short-Lived in the Brain

Our eyes see millions of things every single day. It doesn’t take much to realize that in a visual field, we tend to look at the most distinctive, or salient, features: a bright, red, feather boa among black suits is more eye-catching than a dark-grey tie, for example. But a new study has found that the human brain retains information of distinctive features for only a short period of time.

According to psychologists Mieke Donk and Wieske van Zoest of the Vrije Universiteit in Amsterdam, vision is only affected by salient features for a limited amount of time after the presentation of a visual scene.

In their experiment, the researchers had participants look at a series of displays, each with two singletons that had been orientated to various degrees. The participants had to make an eye movement towards the more salient object in each display. If information regarding distinctiveness was retained, participants would be able to perform this task irrespective of the amount of time it took them to respond.

The results, published in the July issue of Psychological Science, a journal of the Association for Psychological Science, were rather surprising. As the latency of eye movements increased, participants became less accurate in correctly making an eye movement towards the more salient singleton. In fact, performance dropped to chance level for high-latency eye movements. This refuted the researchers’ initial hypothesis that humans have unlimited access to salience information. When the experiment was repeated with displays presented for different amounts of time, this time having participants manually indicate which singleton was more conspicuous, the results were the same: people were less well able to indicate the location of the more salient singleton when display presentation time increased.

According to the authors “These results suggest that salience is represented in the visual system only briefly after a visual image enters the brain.”

Previous studies on saliency demonstrated that in free-viewing conditions, participants were able to identify distinctive objects in a visual field even after a longer period of time. It is possible, therefore, that salient information was re-sent to the brain when eye movements were made. “Further studies may be able to provide insight into how the transience of salience affects visual search in the course of a sequence of eye movements,” the authors concluded.