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Measuring the size of mental images
Journal of Experimental Psychology. Human Perception and Performance
|February 1, 1979
Summary
Researchers measured the physical size of mental images using visual angle. Findings indicate that imagined letters occupy a measurable visual space, with implications for understanding mental imagery.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Visual Perception
Background:
- Mental images appear to possess spatial dimensions.
- Quantifying the physical size of mental images has been an experimental challenge.
- Understanding the relationship between mental imagery and physical measurement is crucial.
Purpose of the Study:
- To experimentally measure the size of mental images in degrees of visual angle.
- To map the subjective experience of mental image size onto objective physical scales.
- To investigate the relationship between imagined letter strings and visual angle.
Main Methods:
- Experiment 1: Participants used light pointers to demarcate the perceived horizontal extent of imagined words (letter strings).
- Experiment 2: Eye-movement responses were recorded to objectively measure the visual angle of imagined letter strings.
- Both experiments focused on quantifying mental image size in degrees of visual angle.
Main Results:
- In Experiment 1, imagined words were estimated to span approximately 1.0 degree of visual angle per letter.
- Experiment 2 demonstrated a regular increase in eye-movement visual angle with greater letter distances in imagined strings.
- Each letter in four-letter strings occupied roughly 2.5 degrees of visual angle under default conditions.
Conclusions:
- Mental images, specifically imagined letter strings, can be quantified in terms of physical visual angle.
- The size of mental images correlates with measurable physical units, suggesting a spatial representation.
- Further research is needed to explore the complex relationship between eye movements and the nature of mental imagery.
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