Real World Context Improves Color Memory

Human memory is at the heart of all we do. From remembering the face of a new acquaintance to locating the cell phone that was just left on a table, one’s “visual working memory”—the primary cognitive system that maintains visual information in an active state for a brief amount of time—is critical.

Previous research has discovered that visual working memory capacity is highly correlated with other important cognitive abilities such as academic performance and fluid intelligence, which includes general reasoning and problem solving, so understanding its limits is critical to understanding how human cognition works.

Previously, ideas stated that an individual’s capacity for visual working memory is fixed, but a recent Dartmouth-led study indicates that when stimuli are relevant, more visual information can be kept, suggesting that visual working memory capacity is flexible. The findings have been published in Psychological Science.

“Our findings broadly suggest that the capacity for visual working memory may be more continuous and flexible than we thought,” says lead author Yong Hoon Chung, a Ph.D. student in cognitive neuroscience and member of the Perception, Attention, and Memory Laboratory at Dartmouth.

In one experiment, participants were shown photos of four distinct colored items on a single computer screen and asked to recall the colors as best they could. They were shown identifiable objects in the “meaningful” state and scrambled versions of the objects in the “meaningless” state.

They were then shown a blank computer screen. They were then shown an image of one of the things or scrambled copies of the objects in two different colors and asked to identify the color they had just seen. Participants were never asked about the object’s identify, simply its color. “What color did you see?” not “Did you see a tea kettle?” was the task. Participants were then shown hundreds of objects as well as scrambled objects in random hues, and their color memory was examined.

The researchers assessed participants’ ability to remember the colors of identifiable real-world things, such as a tea kettle, versus an unrecognizable imitation of the object in a series of five studies. To turn the known object into a scrambled, abstract shape with equivalent visual complexity, the team employed an algorithm created by other academics.

The original and scrambled items were then randomly colored using a 360-degree color wheel. The assumption was that the brain’s earlier visual processing would be similar across intact and scrambled items, but the scrambled things would be unidentifiable to the observers. The meaning of the stimuli would thus be erased by scrambling the item.

The researchers compared how well individuals remembered the colors of the stimuli in meaningful and meaningless settings.

“Our results show that participants’ memory for color was better when they had a meaningful context,” says Chung. “For example, people could remember the color blue better when it was part of a blue kettle than the scrambled blue shape of a jacket. When colors are seen as part of something meaningful, you are more likely to remember that color,” says Chung.

The other studies in the study were comparable and functioned as controls to see if color memory would improve with identifiable objects, which it did. To rule out the possibility that color memory of the stimuli was attributable to verbalizing what was seen or adding a spatial clue during retrieval, the controls included employing upside-down stimuli instead of scrambled items or adding a vocal task on top of the visual task.

“Prior research has shown that space is one of the strongest cues that our visual working memory system uses, as it is kind of baked in to our visual representations, so we were also interested in examining if the effect of meaningfulness would remain when participants could use spatial locations to retrieve the colors,” says senior author Viola Störmer, an assistant professor of psychological and brain sciences, and principal investigator of the Perception, Attention, and Memory Laboratory at Dartmouth.

“What we found is that participants continued to remember the colors better when they were part of real-world objects and didn’t only rely on the spatial locations of where the object was seen.”

“Our study demonstrates that this higher-level semantic meaning, which draws on the long-term storage of general knowledge or in this case the recognition of an object, can help make a really low-level feature that’s not meaningful by itself, like color, meaningful,” says Störmer. “When relatively abstract information is combined with conceptual knowledge that people already have, this can enhance one’s capacity to retain this new information better.”

“A lot of working memory measures are used as diagnostic tools in clinical settings to help identify deficits in memory, but they are based on the assumption that there is a fixed capacity for this type of memory,” says Chung. “So, how we are testing in those fields might not necessarily be as accurate as we originally thought. It may be time to rethink the testing methodologies in order to obtain a more accurate measure of human memory,” says Chung.

“Beyond the clinical setting, our findings may also have implications for how artificial intelligence systems model and manipulate human behavior, as working memory capacity is known to be related to general capacity of human cognition.”

The study builds on Störmer’s previous co-authored work, which discovered that the ability to remember real-world items is superior to the ability to remember abstract concepts.

To better understand how the brain responds to the visual context of colors, the team intends to explore the fundamental mechanisms of visual working memory utilizing electroencephalogram (EEG) and fMRI technologies.

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