Affective content of simple geometric shapes promotes visual size perception

Area of Science:

• Cognitive Psychology
• Neuroscience
• Visual Perception

Background:

• Emotion-cognition interactions are often studied using threat stimuli like fearful faces.
• Geometric features, such as sharp contours, may contribute to the perceived threat of complex stimuli.
• The Ebbinghaus illusion is a well-established phenomenon demonstrating visual size distortion.

Purpose of the Study:

• To investigate if geometric shapes (V-shapes) can modulate visual size perception like threat stimuli.
• To examine the influence of prime duration and presentation eccentricity on this modulation.
• To determine the role of the prefrontal cortex in mediating this effect.

Main Methods:

• Using downward-pointing V shapes and curved shapes as primes to modulate the Ebbinghaus illusion.
• Varying prime presentation duration (150 ms vs. 16.7 ms) and eccentricity (4° vs. 8°).
• Employing intermittent theta burst stimulation to excite the right dorsolateral prefrontal cortex.

Main Results:

• V-shape primes significantly reduced Ebbinghaus illusion strength compared to curved primes at long durations (150 ms).
• At short durations (16.7 ms), this effect was significant only for central, not peripheral, presentation.
• Excitation of the right dorsolateral prefrontal cortex abolished the threat-related modulation effect.

Conclusions:

• Geometric shapes with threat-related features can influence visual perception similarly to explicit threat stimuli.
• This effect necessitates detailed geometric processing and relies on top-down cognitive control from the prefrontal cortex.
• The findings highlight the intricate relationship between geometric form, threat perception, and visual processing.