Image- and Task-Based Contributions to Human Object Localization in Natural Scenes
Colin S. Flowers, Mary A. Peterson · Journal of Vision · 2021
To investigate object localization in natural scenes, we presented a flickering dot probe in 384 color photographs (100 ms; masked). Participants reported whether the probe was “on” or “off” the object bounded by the nearest border. Object localization sensitivity (d') was > 1.0 (VSS 2019). Now, we compared performance with these masked photographs under three conditions. Participants (1) made a localization judgment only (N = 39), (2) also made an object categorization judgment (N = 48), or (3) made a localization judgment on photographs preceded by one of three intermixed primes: a neutral letter string or a word denoting either the object near the probe or a different object (N = 122; ~40/prime condition). Photograph-based analyses of d' and criterion (c) were conducted for each task. Sensitivity was higher when participants made localization responses only (d' = 1.26) than when they also made categorization judgments or when any prime preceded the photographs, [F(4,1532) = 12.385, p 0.165; p’s <0.01): As complexity increased, the bias to respond ‘on’ increased. We consider how attention, object borders, and distinct task requirements contribute to these effects of task and complexity on both object localization sensitivity and participants’ criterion.