Summary: A new study introduces an objective way to measure individual differences in perceptual capacity, showing that people tend to perform consistently across different perceptual tasks.
Source: UCL.
Some people display notably greater perceptual ability, able to spot objects in cluttered scenes, detect changes after very brief exposures, and notice items outside their current focus of attention. A new UCL study presents an objective testing method for measuring this perceptual capacity and shows that it varies reliably across individuals.
The research, published in the Journal of Experimental Psychology: Human Perception and Performance, defines perceptual capacity as the number of items a person can perceive and detect at once. The authors found that individuals show a consistent level of performance across a range of perceptual tasks. For example, participants who were better at detecting a single change in a busy image also tended to be more accurate when tracking several moving objects, more likely to detect unattended items, and more successful at instantly recognizing the number of objects briefly presented to them.
The study is the first to demonstrate that perceptual capacity is a distinct, measurable trait that differs between people. Importantly, this capacity is separate from broader cognitive abilities and cannot be explained simply by working memory capacity — the amount of information someone can actively hold and process in the short term. Factor analyses in the study revealed two orthogonal factors: one reflecting perceptual capacity and another reflecting working memory, indicating these are independent constructs.
Researchers showed that simple, objective tests can predict an individual’s overall perceptual capacity. One example is a brief enumeration test that measures subitizing — the rapid, near-instant ability to identify the number of items in a small set when those items are shown for a fraction of a second. From performance on this task the researchers derived a personal “breakpoint,” the limit at which a person could no longer accurately perceive the number of items instantly. That breakpoint proved to be a reliable predictor of that person’s performance across the other perceptual tasks in the study.
In practice, a short battery of computerized measures combining enumeration, change detection, multiple object tracking, and load-based perception tasks could serve as a robust assessment of perceptual capacity. The authors suggest this testing approach could provide a scientific basis for selection or screening in safety-critical roles — for example, pilots, air traffic controllers, or security personnel who must monitor complex, high-load displays and rapidly detect important events.
Part of the research was conducted at the Science Museum in London, where members of the public completed the tests. Museum visitors took the subitizing task and a change-detection task that presented pairs of busy street scenes differing by a single change. Performance on the quick enumeration task predicted how well the same individuals detected changes in those scenes, reinforcing the idea of a common perceptual capacity underlying different measures.
Source: UCL
Publisher: Organized by NeuroscienceNews.com
Image Source: Image adapted from the UCL news release.
Original Research: Abstract for “Establishing individual differences in perceptual capacity” by Eayrs, Joshua and Lavie, Nilli in Journal of Experimental Psychology: Human Perception and Performance. Published April 23, 2018.
doi: 10.1037/xhp0000530
UCL. “People Differ in Their Power of Perception.” NeuroscienceNews. 25 April 2018. (Adapted summary.)
Abstract
Establishing individual differences in perceptual capacity
Visual perception has a limited capacity, which can give rise to inattentional blindness under high perceptual load. The authors propose a generalized perceptual capacity that underlies several well-known phenomena, including subitizing — the rapid enumeration of a small number of items from a brief display. To test this, they measured individual performance across tasks that load visual perception: change blindness, load-induced blindness, and multiple object tracking, alongside an enumeration task to estimate subitizing capacity. Subitizing capacity consistently predicted performance in the other perceptual tasks, beyond any general factors related to estimating larger set sizes. When working memory measures were included, factor analysis separated perceptual capacity and working memory into distinct, orthogonal factors. These results support the existence of a generalized visual perceptual capacity and establish subitizing as a useful predictor of individual susceptibility to perceptual failures under load.