摘要：The SNARC effect specifically relates small magnitudes to the left hand side and
larger magnitudes to the right hand side (e.g. Dehaene et al., 1990; Dehaene et
al., 1993). It is certain that cultural characteristics define the SNARC effect:
In western cultures small and large numbers are coded in a left-right direction
while in Arabic countries magnitude infor-mation is coded from right to left
(Dehaene et al., 1993; Zebian, in press). In this sense, reading and writing
direction have been considered to be the main determinants of the SNARC effect.
Indeed, a number of recent studies support the idea that the mastering of a
language (and thus reading and writing direction) biases scanning habit in a
favourable di-rection (e.g. Chatterjee et al., 1999; Padakanaya et al., 2002).
If this is indeed the case, it is not surprising that the SNARC effect has been
found with stimuli other than numbers (Gevers et al., 2004). Related to this,
future research could address the question if magnitude and ordinal information
are processed by the same mechanism or by different mechanisms with similar
properties. However, reading and writing direction alone are not sufficient to
explain all SNARC related findings. For instance, it does not allow for an
explanation of a vertical SNARC effect as observed by Schwarz and Keus (2004).
Apparently, other variables are important in the onset of an association between
numbers and space. Furthermore, the existence of a SNARC effect in the vertical
dimension could indicate that the number line can be conceptually extended to a
number map. Another puzzling question is to what reference frame the
SNARC effect is based. Based on the finding of a SNARC effect with both
unimanual (Fischer, 2003a) and oculomotor responses (Fischer et al., 2004;
Schwarz & Keus, 2004) at this moment an egocentric alloca-tion of the SNARC
effect does not seem feasible. On the other hand, both behavioural
(e.g. Bächtold et al., 1998) and neuropsychological studies (Veuilleumier et
al., 2004) point out that the mental representation of numerical information in
itself is of major importance to the SNARC effect. One recent study
provided a first step to relate the SNARC effect to other conflict tasks
(Mapelli et al., 2003). Directly comparing the SNARC effect with the Simon
effect resulted in additive relations between both effects. The question what
the exact cause of this additive relation is remains an interesting topic.
Furthermore, it could also be worthwhile to contrast the SNARC effect with other
conflict tasks such as the Stroop task and the Eriksen Flanker task. To
conclude, 10 years of research on the SNARC effect have unravelled interesting
is-sues regarding the spatial coding of numerical information, fingers crossed
for the following 10.
关键词：SNARC-effect, Spatial Numerical Association of Response Codes, reading and
writing direction, mental representation of numerical information
