Dissociable effects of stimulus range on perception and action

Area of Science:

• Cognitive Psychology
• Neuroscience
• Human Perception

Background:

• The just noticeable difference (JND) is influenced by the range of stimuli presented.
• Previous research indicated that a wider range of standard stimuli increases the JND for perceptual estimations.

Purpose of the Study:

• To investigate whether the range of standards effect (RSE) applies to action as well as perception.
• To differentiate the mechanisms underlying visual perception and visually controlled action.

Main Methods:

• Participants perceptually estimated object sizes under varying ranges of standard stimuli.
• Participants physically grasped objects (action) under varying ranges of standard stimuli.
• The just noticeable difference (JND) was measured in both perceptual and action tasks.

Main Results:

• The range of standards effect (RSE) was observed in perceptual size estimations, where JND increased with a wider stimulus range.
• The RSE was not observed in the action task; JND remained invariant regardless of the stimulus range during grasping.
• This dissociation indicates a difference in how perception and action process stimulus range information.

Conclusions:

• The range of standards effect is specific to perceptual estimations and does not extend to motor actions.
• Visual perception and visually controlled action are governed by distinct rules and potentially different neural mechanisms.
• This finding supports a dual-route hypothesis for visual processing, separating perceptual interpretation from action execution.