The reason which is generally given in the usage-based literature to account for the retention of irregularity in high frequency items during analogical change is entrenchment: a frequently occurring irregular linguistic unit resists analogical levelling because it is highly entrenched in speakers’ mental lexicons through its repeated use. Although previous research similarly suggests that the entrenchment of irregular and regularised forms competing during analogical levelling should be proportional to their frequency of use, evidence for this relation between frequency and entrenchment (...) comes exclusively from corpus-based studies; what is missing, therefore, are behavioural tests contrasting the competing innovative and conservative forms. The present paper aims to provide converging evidence for an entrenchment-based explanation of frequency patterns in analogical change on the basis of data obtained from an experiment in which participants are presented with traditional and analogical variants of a variable currently undergoing analogical levelling. Differences in processing latencies obtained during the experiment are interpreted as differences in entrenchment. The results provide i) evidence in favour of the prevalent entrenchment-based explanation of the conserving effect of frequency in analogical change, and ii) evidence of the current state and spread of the change under investigation. (shrink)