The effects of inverting natural stimuli in a flanker task.

The flanker task developed by B. A. Eriksen and C. W. Eriksen (1974) is a reliable method of showing the effect of flanking stimuli (flankers) on responses to central targets. When flankers map to the same or different responses as the targets, response latencies reduce or increase, respectively, relative to neutral flankers. In Experiment 1, the authors present 2-dimensional line drawings of structurally distinct animals: 2 birds, 2 bugs, and 2 dogs. These pairs generated a reliable flanker compatibility effect (FCE) for both upright and inverted flankers. In Experiment 2, the authors present pairs of structurally similar animals: 2 dogs, 2 cows, and 2 horses. These produced a reliable FCE for only upright flankers. The results are discussed in line with structural categorisation of stimuli being invariant of object orientation.