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Flanker and negative flanker effects in letter identification.
Jeffrey N Rouder1, Jonathan W King
1Department of Psychological Sciences, University of Missouri, Columbia, Missouri 65211, USA. jeff@banta.psyc.missouri.edu
Perception & Psychophysics
|April 26, 2003
Summary
This study reveals two distinct flanker effects in reaction time tasks. Standard flanker effects involve response competition, while a novel negative flanker effect on morphed letters suggests contrast enhancement in perception.
Area of Science:
- Cognitive Psychology
- Perceptual Psychology
Background:
- Flanker effects in reaction time tasks demonstrate how surrounding stimuli influence target responses.
- The standard explanation for flanker effects is response competition, as proposed by Eriksen and Eriksen (1974).
Purpose of the Study:
- To investigate novel flanker effects using morphed letter targets.
- To differentiate between perceptual contrast enhancement and response competition mechanisms.
Main Methods:
- A modified Eriksen task was employed with both standard and morphed letter targets and flankers.
- Reaction times and accuracy were measured to assess response patterns.
Main Results:
- Classic flanker effects were observed for well-formed targets.
- A negative flanker effect, an opposite pattern, was found for morphed letter targets, where flankers influenced target identification.
- Morphed targets (e.g., A/H) were more likely identified as the non-target letter when flanked by it (e.g., 'A' target flanked by 'H').
Conclusions:
- Two distinct mechanisms underlie flanker effects: contrast enhancement in perception and response competition in selection.
- Morphed stimuli reveal perceptual influences, while standard stimuli highlight response competition.