Abstract
Perception famously involves both bottom-up and top-down processes. The latter are influenced by our previous knowledge and expectations about the world. In recent years, many studies have focused on the role of expectations in perception in general, and in object processing in particular. Yet studying this question is not an easy feat, requiring—among other things—the creation and validation of appropriate stimuli. Here, we introduce the ObjAct stimulus-set of free-to-use, highly controlled real-life scenes, on which critical objects are pasted. All scenes depict human agents performing an action with an object that is either congruent or incongruent with the action. The focus on human actions yields highly constraining contexts, strengthening congruency effects. The stimuli were analyzed for low-level properties, using the SHINE toolbox to control for luminance and contrast, and using a deep convolutional neural network to mimic V1 processing and potentially discover other low-level factors that might differ between congruent and incongruent scenes. Two online validation studies (N = 500) were also conducted to assess the congruency manipulation and collect additional ratings of our images (e.g., arousal, likeability, visual complexity). We also provide full descriptions of the online sources from which all images were taken, as well as verbal descriptions of their content. Taken together, this extensive validation and characterization procedure makes the ObjAct stimulus-set highly informative and easy to use for future researchers in multiple fields, from object and scene processing, through top-down contextual effects, to the study of actions.
Highlights
Despite what they might think, people do not see the world “as it is”: top-down processes, such as knowledge, memories, and feelings, affect what we perceive, as we continually evaluate our surroundings and act (e.g., Gilbert & Li, 2013; Gilbert & Sigman, 2007; Lupyan, 2015; but see Firestone & Scholl, 2016)
Behav Res (2021) 53:1895–1909 object within the scene to be invariant to some degree, so it is more likely to appear in a specific location within the setting than in others; and (e) we expect objects to appear in their familiar size, which should match the setting in which they are located
For each context image, we searched for images of the congruent and incongruent objects, in an attempt to find the best fit in terms of size, lighting, sharpness, and orientation
Summary
Despite what they might think, people do not see the world “as it is”: top-down processes, such as knowledge, memories, and feelings, affect what we perceive, as we continually evaluate our surroundings and act (e.g., Gilbert & Li, 2013; Gilbert & Sigman, 2007; Lupyan, 2015; but see Firestone & Scholl, 2016). When we see a scene, we expect particular objects to be in it, and when we see an object, we have expectations regarding the scene in which it appears. What happens when these expectations are violated?. The most widely studied types of incongruencies have focused on objects’ probability of appearing in specific settings or within specific contexts. Such incongruencies have been studied in different ways. Again, some manipulated the probability of the object being in the scene (e.g., Bonitz & Gordon, 2008; Zacharia, Ahuja, Kaur, Mehta, & Sharma, 2020), while others manipulated its probability of being in a certain location in the scene (e.g., Võ & Wolfe, 2013), or the object’s obedience to the rules of gravity (e.g., Võ & Henderson, 2011)
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