Poster #: 95
Thursday, Sep 10, 2015
The relation between psychophysiological and behavioural measures of expectancy and prediction in a roving mismatch negativity paradigm
1Health and Human Sciences, SCU, Coffs Harbour, Australia
Perruchet (1985) reported that as the number of reinforced trials in an eyeblink conditioning preparation increased, participants’ expectation that the next trial would be reinforced decreased. Simultaneously, however, conditioned eyeblink responding was strengthened. These data are often cited as evidence for a discontinuity between explicit and implicit processes in learning. We wished to examine whether a similar discontinuity might exist in an MMN paradigm when the run-length of standards was sufficiently long for participants to begin to expect a deviant was likely. An auditory roving MMN procedure was employed with sequence lengths determined using a hazard function over short (2-3), medium (4-6) and long (7-24) runs. MMN measured at F4 in the 170-190ms window was a linear function of sequence length. The amplitude of a component measured between 300 and 330ms post stimulus onset showed evidence of a quadratic trend. RTs were also largely linearly related to run length, for both deviants and standards. However closer examination of individual run lengths revealed some indication of an increase in RT to standards and a decrease to deviants at long run lengths (greater than 15 trials). Although this experiment failed to provide conclusive evidence for the discontinuity described by Perruchet it is possible that a change in the behavioural response occurs after a relatively large number of trials in the sequence and that the run lengths chosen here were simply not long enough for this effect to be detected. This possibility warrants further attention.