Macaques preferentially attend to visual patterns with higher fractal dimension contours

Area of Science:

• Neuroscience
• Evolutionary Biology
• Visual Perception

Background:

• Animal sensory systems evolve for niche-specific information processing.
• Natural environments feature complex shapes and textures crucial for survival.
• Vision is primary for primates, necessitating sophisticated visual processing.

Purpose of the Study:

• To investigate if sensitivity to fractal dimension, a measure of visual complexity, is an evolutionarily conserved trait.
• To test this hypothesis in rhesus macaques (Macaca mulatta).

Main Methods:

• Monkeys viewed paired images with varying fractal dimensions.
• Noninvasive infrared eye tracking measured attention to stimuli.
• Fixation duration and frequency were analyzed.

Main Results:

• Rhesus macaques demonstrated longer fixations and dwell times on images with higher fractal dimensions.
• Attentional biases were observed towards stimuli with greater visual complexity.
• Monkeys discriminated between visual stimuli based on fractal dimension.

Conclusions:

• Rhesus macaques, like humans, can discriminate visual stimuli by fractal dimension.
• Preference for information-rich visual stimuli may be a conserved trait.
• Sensitivity to fractal dimension could be a widespread ability in vertebrate vision.