Task-demands can immediately reverse the effects of sensory-driven saliency in complex visual stimuli

Area of Science:

• Visual perception
• Cognitive neuroscience
• Attention research

Background:

• Natural vision involves both stimulus-driven (bottom-up) and task-dependent (top-down) attentional control.
• The extent to which task demands can override sensory signals is debated.

Purpose of the Study:

• To investigate how task demands influence attention in naturalistic visual scenes.
• To determine if task demands can fully counteract or even reverse sensory-driven saliency.

Main Methods:

• Recorded human eye movements viewing outdoor scene photographs.
• Manipulated stimulus saliency using contrast gradients and flicker.
• Implemented different search tasks: free-viewing, bull's-eye template search, and oddity search.

Main Results:

• In free-viewing, attention was drawn to high-contrast (high-saliency) areas.
• Task demands overrode sensory bias, directing attention to targets regardless of saliency.
• Attention could be reversed to low-saliency areas when they contained the target.
• Search for a known template target induced stronger top-down drive than oddity search.

Conclusions:

• Task demands can rapidly override and reverse sensory-driven visual saliency.
• The degree of overriding depends on the search target and the specific visual feature.
• Top-down control is a powerful modulator of attention in complex visual environments.