Enumeration: Experts take their time

Previous research has demonstrated that grouping information enhances enumeration, and that this advantage is significantly greater for observers with expertise in dynamic visuospatial tasks (e.g. air traffic controllers). We sought to elucidate whether this advantage is the result of over‐learned, automated responding in an enumeration experiment where many of the stimuli were incongruent as to canonical arrangement and numerosity. If so, we predicted that experts' performance would be more severely affected than novices'; if not, and experts continued to perform better than novices, we predicted that their response times should increase, reflective of the additional cognitive load needed. We demonstrated the latter is so. Experts continued to out‐perform novices but their response times were significantly slower suggesting that expertise is not rigid and automatic but, rather, is flexible and responsive to the specific situation, allowing experts to switch between strategies. Copyright © 2010 John Wiley & Sons, Ltd.