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Global precedence and response activation: evidence from LRPs.
1Department of Psychology, University of Otago, Dunedin, New Zealand. miller@otago.ac.nz
Summary
Global shapes can automatically trigger responses, even when irrelevant, influencing reaction times. This early activation of global information impacts visual processing before local shape recognition.
Area of Science:
- Cognitive Psychology
- Neuroscience
- Visual Perception
Background:
- The global advantage phenomenon describes how larger, global shapes are often processed faster than smaller, local shapes.
- Understanding the neural mechanisms underlying this advantage is crucial for cognitive models of visual processing.
Purpose of the Study:
- To investigate the role of global shape information in response activation using lateralized readiness potentials (LRPs).
- To examine whether global shape processing influences response selection even when it is irrelevant or leads to inhibition.
Main Methods:
- Measured lateralized readiness potentials (LRPs) in participants performing left/right/no-go tasks with compound global/local stimuli.
- Experiment 1: Participants responded to local targets while ignoring global shapes.
- Experiment 2: Participants responded to conjunctions of global and local targets, inhibiting responses when targets appeared at only one level.
Main Results:
- Irrelevant global shapes activated associated responses, affecting reaction times based on congruence with local targets.
- In no-go trials, global shapes initiated response activation, whereas local shapes did not.
- Evidence suggests early activation of global shape information preceding local shape recognition and response initiation.
Conclusions:
- Findings support partial-output models where global shape information can partially activate responses.
- Demonstrates that the global advantage emerges early in visual processing, influencing response selection before full local recognition.