Perceived diagonals in grids and lattices

Area of Science:

• Visual perception
• Computational neuroscience

Background:

• Repetitive grid patterns can elicit illusory diagonal lines.
• These lines possess reverse contrast relative to the grid.
• Existing models struggle to explain this phenomenon fully.

Purpose of the Study:

• Investigate the underlying mechanisms of illusory diagonal lines in grid patterns.
• Determine if global Fourier components or specific filtering explain the lines.
• Propose a novel model for visual processing of such patterns.

Main Methods:

• Analysis of grid patterns and dot lattices.
• Testing explanations based on global Fourier components.
• Evaluating low-pass orientation-specific filtering.
• Developing a model based on local feature detection and integration.

Main Results:

• Illusory diagonal lines are observed in grids but not dot lattices.
• The lines are not explained by global Fourier components or low-pass filtering.
• The phenomenon relies on local diagonal components at intersections.
• A model involving local detectors and collector units explains the findings.

Conclusions:

• Illusory diagonal lines in grid patterns result from local visual processing, not global features.
• The proposed model of local detectors and collector units provides a framework for understanding this illusion.
• The model is applicable to related phenomena like subjective contours and the Fraser twisted cord illusion.