Mental Imagery and Visual Working Memory

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Keogh, R., & Pearson, J. (2011). Mental imagery and visual working memory. PLoS ONE, 6(12), e29221. doi:10.1371/journal.pone.0029221

Abstract

Visual working memory provides an essential link between past and future events. Despite recent efforts, capacity limits, their genesis and the underlying neural structures of visual working memory remain unclear. Here we show that performance in visual working memory - but not iconic visual memory - can be predicted by the strength of mental imagery as assessed with binocular rivalry in a given individual. In addition, for individuals with strong imagery, modulating the background luminance diminished performance on visual working memory and imagery tasks, but not working memory for number strings. This suggests that luminance signals were disrupting sensory-based imagery mechanisms and not a general working memory system. Individuals with poor imagery still performed above chance in the visual working memory task, but their performance was not affected by the background luminance, suggesting a dichotomy in strategies for visual working memory: individuals with strong mental imagery rely on sensory-based imagery to support mnemonic performance, while those with poor imagery rely on different strategies. These findings could help reconcile current controversy regarding the mechanism and location of visual mnemonic storage.

Authors

Rebecca Keogh17
Joel Pearson35

What This Study Is About

Researchers investigated whether mental imagery—the ability to picture things in your mind—is the same thing as visual working memory, which is the ability to briefly hold and manipulate visual information. They wanted to see if people with stronger mental images are naturally better at memory tasks that involve pictures.

How They Studied It

The study involved 35 university students who completed several tasks. To measure the strength of their mental imagery objectively, researchers used a "binocular rivalry" test, where different images are shown to each eye and the brain must choose one to see; imagining one of the images beforehand can influence which one the brain picks. Participants also performed visual working memory tasks (remembering the orientation of patterns) and "iconic memory" tasks (remembering very brief flashes of images). In a second experiment with 17 students, researchers used bright background lights to see if "cluttering" the visual system would specifically hurt the memory of people with strong imagery.

What They Found

The researchers discovered that people with stronger mental imagery were significantly better at visual working memory tasks. However, imagery strength had no connection to iconic memory (the very short-term "afterimage" memory). Most importantly, when researchers added background light to interfere with the brain's visual processing, it only lowered the memory scores of people with strong imagery. People with weak imagery (similar to aphantasia) were not affected by the light, and they still performed well on the memory tests.

What This Might Mean

This suggests that there isn't just one way to remember a picture. People with strong mental imagery seem to use their "mind's eye" as a tool to help them remember. People with weak imagery or aphantasia likely use different, non-visual strategies to store the same information. This helps explain why someone might not be able to "see" a memory but can still remember the details of what they saw.

One Interesting Detail

The study found that while background light disrupted the visual memory of "strong imagers," it did not affect their ability to remember strings of numbers. This proves the light was specifically interfering with their mental "pictures," not their general ability to focus or remember things.

Mental Imagery and Visual Working Memory

Abstract

Authors

Mental Imagery and Visual Working Memory

Abstract

Authors

Mental Imagery and Visual Working Memory

Abstract

Authors

Mental Imagery and Visual Working Memory

Abstract

Authors

What This Study Is About

How They Studied It

What They Found

What This Might Mean

One Interesting Detail

What This Study Is About

How They Studied It

What They Found

What This Might Mean

One Interesting Detail

Joel Pearson

Merlin Monzel

Adam Zeman

Rebecca Keogh

Martin Reuter

Juha Silvanto

Paolo Bartolomeo

Carla Dance

Jianghao Liu

Fraser Milton