Asymmetric interference in patterning discriminations: a case of modulated attention

In sequential training positive patterning hinders negative patterning, but not vice versa. This asymmetry was attributed to interference of two different rules. In a Pavlovian skin conductance response conditioning experiment with humans, we further investigated this effect. Two groups performed sequential training of positive and negative patterning with a reduced number of trials per training schedule. In Group PNP, the sequence was positive patterning (A-, B-, AB+), negative patterning (C+, D+, CD-), followed by positive patterning (E-, F-, EF+). Group NPN consisted of negative patterning (A+, B+, AB-), positive patterning (C-, D-, CD+), and negative patterning (E+, F+, EF-) again. As predicted by an attentional explanation we found no interference. Hence, the asymmetry observed earlier had been due to less attention to specific stimuli in consequence of an extensive use of the numerosity-rule.