TY  - JOUR
AU  - Niessen, Eva
AU  - Fink, G. R.
AU  - Schweitzer, L.
AU  - Kluender, N.
AU  - Weiss-Blankenhorn, Peter
TI  - Implicit interactions between number and space indigit-color synesthesia.
JO  - Cortex
VL  - 64
SN  - 0010-9452
CY  - Paris
PB  - Elsevier Masson
M1  - FZJ-2014-07042
SP  - 225 – 234
PY  - 2015
AB  - In digit-color synesthesia, a variant of grapheme-color synesthesia, digits trigger an additional color percept. Recent work on number processing in synesthesia suggests that colors can implicitly elicit numerical representations in digit-color synesthetes implying that synesthesia is bidirectional. Furthermore, morphometric investigations revealed structural differences in the parietal cortex of grapheme-color synesthetes, i.e., in the brain region where interactions between number and space occur in non-synesthetic subjects. Based upon these previous findings, we here examined whether implicitly evoked numerical representations interact with spatial representations in synesthesia in such a way that even a non-numerical, visuo-spatial task (here: line bisection) is modulated, i.e., whether synesthetes exhibit a systematic bisection bias for colored lines.Thirteen digit-color synesthetes were asked to bisect two sets of lines which were colored in their individual synesthetic colors associated with a small or a large digit, respectively. For all colored line stimuli combined, digit-color synesthetes showed – like control subjects (n = 13, matched for age, gender, IQ and handedness) – a pseudo-neglect when bisecting colored lines. Measuring the color-induced change of the bisection bias (i.e., comparing the biases when bisecting lines colored according to a small number vs those lines corresponding to a large number) revealed that only digit-color synesthetes were significantly influenced by line color.The results provide further evidence for the bidirectional nature of synesthesia and support the concept of a mental number line. In addition, they extend previous reports on bidirectionality in synesthesia by showing that even non-numerical, visuo-spatial performance can be modulated by implicit bidirectional processes.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000351248400021
C6  - pmid:25498947
DO  - DOI:10.1016/j.cortex.2014.11.001
UR  - https://juser.fz-juelich.de/record/185616
ER  -