The Snodgrass and Vanderwart set revisited: norms for object manipulability and for pictorial ambiguity of objects, chimeric objects, and nonobjects.
Résumé
In this paper, we propose a standardized set of 480 black-and-white line drawings, half meaningful and half meaningless. Meaningful pictures represent a common object, and were selected from the Snodgrass and Vanderwart set (1980). Meaningless pictures include 120 chimeric objects (made up of two halves of real objects) and 120 nonobjects, that were constructed from the meaningful pictures while controlling for visual complexity. We report the results of two experiments designed to standardize the revisited Snodgrass and Vanderwart set along two important dimensions for picture processing: object manipulability (Experiment 1) and pictorial ambiguity (Experiment 2). The relevance of these dimensions is discussed. Experiment 1 permit us to sort objects into four manipulability categories (i.e., the ease and distinctiveness with which use of the object can be mimed) and to propose a manipulability index. This experiment provides additional evidence for a partial overlap in the dichotomy between man-made objects and living things, on the one hand, and manipulable and unmanipulable objects, on the other hand. In Experiment 2, a pictorial ambiguity index was computed for meaningful and meaningless pictures. The results of this experiment point the distinction between chimeric objects and nonobjects showing that chimeric objects are more complex to process than nonobjects and objects. This standardized set of pictures provides a database and an hopefully useful tool for research in cognitive neuroscience.