Effects of part-based similarity on visual search: the Frankenbear experiment

Abstract

Do the target-distractor and distractor-distractor similarity relationships known to exist for simple stimuli extend to real-world objects, and are these effects expressed in search guidance or target verification? Parts of photorealistic distractors were replaced with target parts to create four levels of target-distractor similarity under heterogenous and homogenous conditions. We found that increasing target-distractor similarity and decreasing distractor-distractor similarity impaired search guidance and target verification, but that target-distractor similarity and heterogeneity/homogeneity interacted only in measures of guidance; distractor homogeneity lessens effects of target-distractor similarity by causing gaze to fixate the target sooner, not by speeding target detection following its fixation.

Figure 1

Examples of target and distractor teddy bears from each T-D similarity condition. 0-part, 1-part, 2-part, and 3-part refer to the number of parts from a distractor that were matched to the target.

Figure 2

Representative examples of 0-part similarity search displays in (A) Experiment 1 (heterogenous distractors) and (B) Experiment 2 (homogenous distractors).

Figure 3

The procedure for a representative 3-part target absent trial in Experiment 1.

Figure 4

Time-to-target (A) and target verification time (B) for correct target present trials in Experiments 1 and 2. Error bars show 95% confidence intervals.

Figure 5

Percentage of trials in which the target was the first object fixated in Experiments 1 and 2. Error bars show 95% confidence intervals. The dashed line indicates chance.