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Spatial filtering and the Zöllner-Judd geometrical illusion: further studies
1Department of Psychology, Washington Singer Laboratories, University of Exeter, UK.
Perception
|January 1, 1995
Summary
The Zöllner illusion and Judd illusion are not fully explained by a single band-pass spatial filtering process. New findings suggest a dual-process account may better explain these visual perception effects.
Area of Science:
- Visual Perception
- Computational Neuroscience
- Psychophysics
Background:
- The Zöllner illusion causes perceived non-verticality in lines crossed by oblique lines.
- The Judd illusion leads to perceived compression of vertical spacing.
- A single-process model using difference-of-Gaussians (DOG) filters has been proposed to explain both illusions.
Purpose of the Study:
- To challenge the single-process band-pass filtering account of the Zöllner-Judd illusions.
- To investigate the role of contrast polarity and figure components in these illusions.
- To propose an alternative explanation for the Zöllner-Judd effects.
Main Methods:
- Demonstration of Zöllner-Judd effects with opposite-contrast figures.
- Analysis of illusion presence with and without the main vertical lines.
- Observation of effects with anomalous contours.
Main Results:
- The Zöllner-Judd effects persist with opposite contrast polarity, contradicting DOG filter predictions.
- Normal Zöllner-Judd effects are observed even when the primary vertical lines are absent.
- Illusory effects occur with anomalous contours, further challenging the filtering model.
Conclusions:
- The single-process band-pass filtering model is insufficient to explain the Zöllner-Judd illusions.
- Findings support a dual-process account for these visual perception phenomena.
- The role of contrast and figure components needs further investigation in visual illusions.
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