Effects of Visual Expectation on Perceived Tactile Perception: An Evaluation Method of Surface Texture with Expectation Effect

IntroductionSurface texture is a design factor that consists of physical attributes created by a variety of materials and surface finishes--attributes such as roughness, glossiness, color, and hardness. People perceive and/or predict a surface's characteristics corresponding to each physical attribute through sensory information, a process that we call perceived features (e.g., surface roughness perceived through touch). Using a combination of perceived characteristics of surface texture, people perceive a tactile quality, such as "nice to touch."Directly perceivable surface characteristics differ depending on the kinds of sensory modalities used for perception: for example, people perceive a surface's color by looking at it or perceive its hardness by touching it. Furthermore, some surface characteristics can be perceived through multiple modalities: for example, we can perceive a surface's roughness by looking at it as well as by touching it.In order to design the surface texture of a product, a designer needs to grasp the relationship between the surface's physical attributes, as design parameters, and the customer's psychological response to the surface. This response could be described as how the costumer or user perceives the quality of a product's surface in relation to the particular sensory modality by which the user interacts with the product. Several previous studies have proposed methods to investigate this relationship. A conventional approach has included conducting a sensory evaluation experiment in which participants respond to a set of texture samples, and then the researchers assess the statistical relationships between the physical attributes of the samples and the participants' sensory responses. Such experiments are often conducted using specific sensory modalities, such as vision, touch, or a combination of both. Indeed, studies have been conducted that explore the differences among sensory modalities in terms of perceptual dimensions and sensitivity (Hollins, Bensma, Karlof, & Young, 2000; Picard, Dacremont, Valentin, & Giboreau, 2003).On the other hand, in the course of interacting with a product, a user often switches from one sensory modality to another in order to perceive a target texture quality. In this way, we often first see, and then touch, a surface texture. During such sensory modality transitions, we expect or predict the perceptual experience that we might have through a subsequent sensory modality by first using a prior modality, such as in the case of expecting a particular tactile perception by first looking at a surface texture. However, our prior expectations do not always correspond to our subsequent experience. Such disparities between expectation and actual experience can evoke surprise (Ludden, Schifferstein, & Hekkert, 2009), as well as delight, if the experience exceeds expectations, or disappointment if it does not. For example, in the case of surface texture, a photo of a product in an advertisement may suggest a quality better than that of the actual item, leading to disappointment. This disconfirmation of prior expectations is a factor that affects both positive and negative emotions toward a product and its attributes.On the other hand, prior expectations also affect posterior perceptual experiences--a phenomenon known as the expectation effect. One such case is the size-weight illusion, in which people perceive a smaller object as being heavier than a larger one when the two are actually equal in weight (Flanagan & Beltzner, 2000). People expect the bigger object to be heavier than the smaller one, but when they subsequently hold the objects, they perceive the opposite, even though the weights are the same. In other words, the discrepancy between visual prediction and weight perception works through a contrast effect (Oliver, 1980). With regard to surface texture, however, there have been no studies undertaken or evaluation methods devised for dealing with the expectation effect. …