Implicit versus explicit interference effects in a number-color synesthete.
Ilaria Berteletti, Edward M Hubbard, Marco Zorzi
Cortex; a journal devoted to the study of the nervous system and behavior February 2010 DOI: 10.1016/j.cortex.2008.12.009 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Case study Case report Peer reviewed |
|---|---|
| Sample size | 1 |
| Population | NM, a grapheme-color synesthete |
| Measures | Digit Stroop task, Numerosity Stroop task |
| Key findings | NM showed longer response times in the incongruent condition of both the Digit Stroop and Numerosity Stroop tasks, despite denying any experience of colors for random dot patterns. The authors argue this dissociation indicates that subjective reports should be the primary criterion for distinguishing synesthesia from learned synesthesia-like associations, and that conscious and unconscious interference may stem from qualitatively different mechanisms. |
Abstract
A fundamental question in the study of consciousness is the connection between subjective report and objective measures. We explored this question by testing NM, a grapheme-color synesthete, who experiences colors when viewing digits but not dot patterns. Synesthesia research has traditionally used variants of the Stroop paradigm as an objective correlate of these subjective synesthetic reports. We used both a classical synesthetic Digit Stroop task and a novel Numerosity Stroop task, in which random dot patterns were colored either congruently or incongruently with the colors NM reported for digits. We observed longer response times in the incongruent condition for both tasks, despite the fact that NM denied experiencing colors for random dot patterns, constituting a clear dissociation between subjective and objective measures of synesthetic experience. We argue that distinguishing synesthesia from learned synesthesia-like associations (pseudosynesthesia) should depend primarily on the presence of subjective reports, validated by objective measures. More generally, we suggest that consciously and unconsciously mediated interference may arise from qualitatively different mechanisms.