![]() ![]() 2005), exactly how these descriptors relate to the primary dimensions is not clear. 2003), “blurred”, and “clear” ( Gescheider et al. Although other putative adjectives have been used to describe textures including “thin”, “thick”, “relief”, “harsh” ( Picard et al. The perceptual space for tactile textures during direct touch is spanned by the primary dimensions of roughness, hardness, and stickiness, and to a lesser degree warmth ( Hollins et al. With indirect touch, vibrations must convey texture information, and RA and PC afferents that are sensitive to vibratory stimuli are likely to be employed when textures are scanned through a probe ( Gardner and Palmer 1989a, 1989b Kops and Gardner 1996 Craig and Rollman 1999). 1990 Connor and Johnson 1992 Johnson and Yoshioka 2002). In direct touch, a spatial image of the texture is available in the population response of SA1 afferents ( Connor et al. In other words, the spatial image of the texture that is sent to the central nervous system by the different afferent populations in the two scanning modes is quite different.īecause of this difference in inputs to the nervous system, the neural mechanisms of texture perception differ between direct and indirect touch. In the probe-scanning condition, the information about the surface must rely on transmitted vibrations that quasi-synchronously activate the mechanoreceptors in the hand: no spatial cues are available for texture perception since the pattern of deformation of the skin reflects the contours of the probe rather than the properties of the scanned surface ( Klatzky et al. ![]() When exploring surfaces with the finger (i.e., direct touch), both a crisp two-dimensional spatial image of the texture and vibratory information are available to the receptors in the finger pad. Our motivation for performing this study is the observation that while perception of textures appears intact through a tool, the information available to subjects about the surfaces is different in direct and indirect touch. Although much is known about texture perception with direct touch ( Johnson 2002), less is known about the texture perception with indirect touch, and how the percepts in the two scanning modes are related. Despite this indirect perception of objects through a tool, people experience a rich impression of the surface, not of the tool or the vibrations through it ( Katz 1925/1989 Klatzky et al. Examples include drawing with a pencil, using cooking utensils, or in more special cases, performing minimally invasive surgery with laparoscopic instruments. Given that different types of texture information are processed by separate groups of neurons across direct and indirect touch, we propose that the neural mechanisms underlying texture perception differ between scanning modes.Įxploring the world with probes or tools is a ubiquitous experience in our daily life. Finally, we demonstrate that three physical quantities, vibratory power, compliance, and friction carry roughness, hardness, and stickiness information, predicting perceived dissimilarity of texture pairs with indirect touch. These differences between the two modes of scanning are apparent in perceptual space for tactile textures based on multidimensional scaling (MDS) analysis. From the adjective rating experiments, we found that while roughness ratings are similar, hardness and stickiness ratings tend to differ between scanning conditions. From the dissimilarity judgment experiment, we found that the texture percept is similar though not identical in the two scanning modes. In the second task, subjects rated each texture along three continua, namely, perceived roughness, hardness, and stickiness of the surfaces, shown previously as the primary dimensions of texture perception in direct touch. In the first task, subjects rated the overall pair-wise dissimilarity of the textures. Here we investigate the perception of a variety of textured surfaces encountered daily (e.g., corduroy, paper, and rubber) using the two scanning modes-direct touch through the finger and indirect touch through a probe held in the hand-in two tasks. It is not clear, however, how texture perception with a probe compares with texture perception with the bare finger. Considerable information about the texture of objects can be perceived remotely through a probe. ![]()
0 Comments
Leave a Reply. |