What drives the automatic retrieval of real-world object size knowledge?

Abstract

Real-world object size is a behaviorally relevant object property that is automatically retrieved when viewing object images: participants are faster to indicate the bigger of two object images when this object is also bigger in the real world. What drives this size Stroop effect? One possibility is that real-world size is automatically retrieved after the objects are recognized. Alternatively, the effect may be driven by automatic associations between mid-level visual features (e.g., rectilinearity) and real-world size, bypassing object recognition. Here, we tested both accounts. In Experiment 1, objects were displayed upright and inverted, disrupting recognition while equating visual features. Inversion strongly reduced the Stroop effect. In Experiment 2, the Stroop effect was compared between manmade objects (for which rectilinearity was associated with size) and animals (no association between rectilinearity and size). The size Stroop effect was larger for animals than for manmade objects, indicating that rectilinearity was not primarily driving the Stroop effect. Finally, in Experiment 3, unrecognizable “texform” objects that maintained size-related visual feature differences were displayed upright and inverted. Results revealed a relatively small Stroop effect for both upright and inverted conditions. Altogether, these results indicate that the automatic retrieval of real-world object size knowledge primarily follows object recognition with an additional contribution from visual feature associations.