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Different Mechanisms for Supporting Mental Imagery and Perceptual Representations: Modulation Versus Excitation

DOI: 10.1177/09567976231198435
Pace, T., Koenig-Robert, R., & Pearson, J. (2023). Different mechanisms for supporting mental imagery and perceptual representations: modulation versus excitation. Psychological Science, 34(11), 1229–1243. doi:10.1177/09567976231198435

Abstract

Recent research suggests imagery is functionally equivalent to a weak form of visual perception. Here we report evidence across five independent experiments on adults that perception and imagery are supported by fundamentally different mechanisms: Whereas perceptual representations are largely formed via increases in excitatory activity, imagery representations are largely supported by modulating nonimagined content. We developed two behavioral techniques that allowed us to first put the visual system into a state of adaptation and then probe the additivity of perception and imagery. If imagery drives similar excitatory visual activity to perception, pairing imagery with perceptual adapters should increase the state of adaptation. Whereas pairing weak perception with adapters increased measures of adaptation, pairing imagery reversed their effects. Further experiments demonstrated that these nonadditive effects were due to imagery weakening representations of nonimagined content. Together these data provide empirical evidence that the brain uses categorically different mechanisms to represent imagery and perception.

Authors

  • Thomas Pace1
  • Roger Koenig-Robert1
  • Joel Pearson28

Understanding Mental Imagery and Visual Perception: A New Perspective

Overview/Introduction

Have you ever tried to picture a favorite memory in your mind and noticed that it doesn't feel as vivid as the actual experience? This phenomenon is at the heart of a recent study exploring the differences between mental imagery and visual perception. The research reveals that these two processes are supported by fundamentally different mechanisms in the brain, challenging the common belief that mental imagery is just a weaker form of perception.

Methodology

The study involved five separate experiments with adult participants. Researchers used innovative behavioral techniques to investigate how the brain processes visual perception and mental imagery. Participants were exposed to visual stimuli and asked to either perceive or imagine them. The researchers then measured how these tasks affected the participants' visual adaptation—a process where the brain becomes less sensitive to a constant stimulus over time.

Key Findings

  • Different Mechanisms: The study found that perception and imagery rely on different brain mechanisms. Perception is driven by increased neural activity, while imagery works by modulating or reducing the activity related to non-imagined content.
  • Imagery's Unique Role: When participants imagined visual stimuli, it actually reversed the effects of visual adaptation, unlike perception, which increased adaptation.
  • Imagery Vividness: The vividness of mental imagery played a significant role. More vivid imagery had a stronger effect on reversing adaptation, suggesting that the clearer the mental image, the more it can influence perception.

Implications

These findings suggest that mental imagery is not just a weaker version of perception but a distinct cognitive process. This new understanding could have practical implications in fields like cognitive therapy, education, and even virtual reality, where mental imagery is often used as a tool for learning and treatment. By recognizing the unique mechanisms of imagery, we can better tailor these applications to enhance their effectiveness.

Limitations

While the study provides compelling evidence, it is important to note that it focused on specific visual tasks and may not fully represent how imagery and perception interact in more complex or real-world scenarios. Further research is needed to explore these interactions in different contexts and with more diverse participant groups.
In summary, this research offers a fresh perspective on how our brains process mental imagery and perception, highlighting the unique and complex nature of these cognitive functions. Understanding these differences can pave the way for more effective applications in various fields, enhancing how we use mental imagery in everyday life.