**Part 1**

**Haptic Perception** 

**1** 

**Haptic Concepts** 

*Arizona State University, United States of America* 

Phuong Do, Donald Homa, Ryan Ferguson and Thomas Crawford

A concept may be defined as a collection of objects grouped together by a common name whose members are usually, but not always, generated by a plan or algorithm. All words are concepts, as are the natural categories, esthetic style, the various diseases, and social stereotypes. In virtually all cases, an endless number of discriminably different examples of a concept has been rendered equivalent. A striking example was provided by Bruner, Goodnow, and Austin (1956), who noted that humans can make 7 million color discriminations and yet rely on a relative handful of color names. We categorize, according to Bruner et al., for a number of reasons – it is cognitively adaptive to segment the world into manageable categories, categories once acquired permit inference to novel instances, and concepts, once identified, provide direction for instrumental activity. For example, we avoid poisonous plants, fight or flee when encountering threat, and make decisions following a diagnosis. With rare exceptions, all concepts are acquired by experiences that

However, the substantial and growing literature on formal models of concepts (e.g., Busemeyer & Pleskac, 2009) and the discovery of variables that shape concepts (e.g., Homa, 1984) has been acquired, almost exclusively, from studies that investigate the appearance of objects, i.e., the presentation of stimuli that are apprehended visually. Yet a moment's reflection reveals that our common concepts are associated with inputs from the various modalities. The taste, texture, odor, and appearance of food might critically inform us that this food is spoiled and not fresh; that the distinctive shape, gait, and sound marks this stray dog as probably lost and not dangerous; and the sounds, odors, and handling might be telling us that the family car needs a tune-up. Little is known about haptic or auditory concepts and virtually nothing is known about cross-modal transfer of categorical information between the different modalities, at least not from formal, experimental studies. In contrast to the dearth of studies involving multimodal input and cross-modal transfer in category formation, there exists ample, albeit indirect, support for the role of multimodal properties revealed from other cognitive paradigms, ranging from feature and associative listing of words and category instances to the solution of analogies and logical decisionmaking. When asked to list attributes of category members (e.g., Garrard, Lambon, Ralph, Hodges, & Patterson, 2001; Rosch & Mervis, 1975), subjects typically include properties drawn from vision, audition, touch, olfaction, and taste. Similarly, the solution of analogies (e.g., Rumelhart & Abrahamson, 1973) and category-based induction (e.g., Osherson, Smith,

**1. Introduction** 

are enormously complex and always unique.
