sequenced motors controlling rhythm and pattern experiments: active and passive touch

Touch and Perception

The dominance of vision as a primary sense seems to deprioritize one of our primary senses, that of touch. Touch differs from vision and hearing because tactile sense is contingent to contact and the receptors used in touch are spread over the whole body. However touch is limited to the area of contact with objects. In this case the passive tactile perception, known as cutaneous perception, is where the stimulations are applied to a stationary segment of the body; where the perceptual field is reduced and is limited to the area of contact to the particular area of the skin (1.) However In cases where the whole object needs to be felt/touched, voluntary movement needs to be made to compensate for the entire tactile perceptual field; wherein which the field may vary according to the area of contact (i.e., finger, whole hand, arm movement, etc.) This form of “active touch,” or haptic behavior requires a mental integration and synthesis to obtain an integrated rendition of the object. In view of this, touch can provide information about the spacial properties of an environment or object as well as allowing for perception of physical properties such as: texture, direction, distance, shape, size, etc. (2.)

With respect to the the anatomical and neurological bases of tactile manual perception, two forms of perception exist. Cutaneous perception and haptic perception; where cutaneous perception is a passive touch (as mentioned above) and haptic perception, where a motor system is involved in the exploratory activity of the hand which in turn can activate the whole shoulder-arm-hand system (thus being an “active” touch.) In cutaneous perceptions the primary point of touch is unvarying, so only the superficial layers of skins experience mechanical deformations and are thus involved in perceptual processing. Whereas with haptic deformations these include the use of muscles, joints and tendons which results from the exploratory movements that were added to the cutaneous perceptions. Therefore, haptic perceptual processing is more complex as it utilizes cutaneous and proprioceptive signals (3.) However it should be noted that active versus passive touch is often theoretically vague. Also, each form of touch has its advantages in different scenarios.

This tactile system, unlike other sensory systems, allows for quick modification, at will, to adjust the size of the perceptual field during exploration, varying from the specific point on an index finger to the full surface of two hands in movement. The use of one or two hands, one or several fingers, and the use or not use of the palms of hands depend on the properties of the engagement, namely with the scale and volume of the object/environment. Therefore, what level of expertise must be manifested by this modality in object identification? According to Klatzky and Lederman, this identification is accomplished primarily through the tactile interaction of the material properties of the objects such as texture, weight and compliance (4.)

In looking at the psychological procedures at work in the cognitive activities of touch, practical outcomes and characteristics of this modality begin to elucidate. Everyday we interact with objects in our environments, use human-computer interfaces to interact, communicate, and perform various tasks. This flow of data is being sent and manipulated in these various tasks, e.g., using a remote, sending emails, checking the stock reports, downloading data through the internet, or controlling the workflow and process of an manufacturing plant. It seems the dominant senses for these types of activities are geared toward audio and visual modalities. However there should be significant efforts in initiating and applying tactile touch objects and interactions to execute these tasks or to improve the experience of these tasks. In view of this, the question of what practicality can be achieved from facilitating such tactile interactions with our objects and environments? To answer this question, my thesis proposes investigating and speculating this tactile and haptic modality.

This experiment uses a plush tactile sensor. The sensor acts as a variable to control the rhythm and pattern sequence. The rhythmic pattern can be seen as an electrical flow, that is then manipulated by touching the sensor. In this experiment I investigated different materials to “touch” the user. First were plastic plants, second were brushes, and third was carpet. Each test material has different affects on how the user interprets the rhythm and pattern.

These were the first iterations of the experiment. With these iterations I investigated different materials to “touch” the user. First were plastic plants (then plastic plants with plastic tubing to limit the field of spread), second were brushes, and third was carpet. Each test material had different effects on how the user interprets the rhythm and pattern.

This experiment uses a plush tactile sensor. The sensor acts as a variable to control the rhythm and pattern of the motors. The rhythmic pattern can be seen as an electrical flow, that is then manipulated by touching the sensor.

This was the initial experiment to the one above, where I began using motors for feedback. This experiment uses a plush tactile sensor. The sensor is attached to the battery and vibrating motor to create for a handheld object. As the user squeezes the object they receive vibrotactile feedback. This object utilizes tactile and force feedback.

1. Grunwald, Martin. Human Haptic Perception: Basics and Applications. Basel: Birkhauser, 2008. Print.
2,3. Paterson, Mark. The Senses of Touch: Haptics, Affects, and Technologies. Oxford: Berg, 2007. Print.
4. Lederman, S.J., and R.L. Klatzky. Action For Perception: A Manual Exploratory Movements for Haptically Processing Objects and Their Features. New York: Academic, 1996. Print.

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