MAGNITUDE VERSUS PARITY IN NUMERICAL JUDGMENTS - EVENT-RELATED BRAIN POTENTIALS IMPLICATE RESPONSE CONFLICT AS THE SOURCE OF INTERFERENCE

When subjects make 'odd/even' and 'low/high' decisions about digits, i nformation about the digit's magnitude can interfere with the decision about the digit's parity. The present experiment used a psychophysiol ogical approach to examine whether this interference arises at the lev el of response processing. Subjects performed a choice-reaction time t ask involving low/high and odd/even judgements about the digits 2 thro ugh 9. The data point to a response locus for the interference effect with the size of the effect being dependent on the ease with which mag nitude information can be used to prime the appropriate response. This , in turn, is influenced by the 'naturalness' of the mapping between m agnitude and response hand as well as by the distance of a digit to th e low/high cut-point.