Representational economy, not processing speed, determines preferred processing strategy of visual patterns

According to Garner, visual patterns are mentally represented as categories rather than by their physical identity. On the other hand, physical and categorical identification tasks engender their own specific processing strategies. Nevertheless, categorical strategies should be more generic than physical ones. We tested this prediction using Garner patterns in a same-different task: one version involved categorical, the other physical identification. Both tasks showed effects of categorical representation but also contrasting categorical and physical processing strategies in their response time profiles. When trials from categorical and physical identification tasks were randomly intermixed, mixing costs were additive for categorical trials but not for physical trials, indicating a shift in processing strategy for the latter. For these trials, the physical response time profile was found to be displaced by a categorical profile. We concluded that the more generic processing strategy is the one that maximizes the role of categorical representation.