Haptic Illusion: Apparent Elongation of a Disk Rotated between the Fingers

Cormack, Robert H.

doi:10.1126/science.179.4073.590

Cited by 10 publications

(5 citation statements)

References 4 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The only example of another instance in which the perceived distance between the fingers is influenced by tactile input are the rotating disk and rotating hourglass illusions [2,6]. When a coin is rotated between thumb and index finger, the coin is perceived to be elongated perpendicular to the rotation axis, while the coin in the direction of the rotation axis sometimes is reported to shrink [2].…”

Section: Resultsmentioning

confidence: 98%

Introducing the shape-length illusion

Plaisier

Ernst

2013

2013 World Haptics Conference (WHC)

View full text Add to dashboard Cite

The size of an object can be perceived by pinching it between thumb and index finger. Here we show a new haptic illusion in which the length of objects with large local curvature is overestimated. Participants pinched ellipses between the thumb and the index finger and matched the size of the major axis to a set of rectangles which carry no curvature information. Ellipses with high local curvature at the contact areas were consistently rated to be larger than those with smaller curvature. This illusion shows that local shape information can influence judgment the size of an object.

show abstract

Section: Resultsmentioning

confidence: 98%

Introducing the shape-length illusion

Plaisier

Ernst

2013

2013 World Haptics Conference (WHC)

View full text Add to dashboard Cite

show abstract

“…While this paper was in preparation, Cormack (1973) reported a similar illusion. Cormack's illusion is obtained by turning a disk edge for edge between the thumb and forefinger.…”

Section: A Tactile Illusiqn 337 Experiments Ii: a Similar Illusionmentioning

confidence: 85%

A tactile illusion: The rotating hourglass

Jones

Touchstone

Gettys

1974

Perception & Psychophysics

View full text Add to dashboard Cite

A new tactile (more properly termed haptic) illusion, the rotating hourglass, was investigated in the laboratory by rotating a rod end for end between the S's thumb and forefinger. This illusion, which is an apparent decrease in the diameter of the rod at the point of contact with the fingers, was easily observed by 19 of the 20 Ss. When the illusion was studied as a function of time, the magnitude of the illusion increased over time with a mean decrease in apparent diameter of 52.3% from the beginning to the end of the 38-sec trials. A theory of differential adaptation of the skin is postulated to explain the rotating hourglass illusion and a similar illusion.This illusion, which we call the rotating hourglass, is an apparent decrease in the diameter of the part of a rotating rod which is in contact with the finger. Most people can experience a weak version of this illusion by using a piece of chalk. To obtain the illusion, hold the chalk in the center with the thumb and forefinger. Then steadily rotate the piece of chalk end over end with the other hand so that each end passes through the circle formed by the thumb and forefinger. While rotating the chalk end for end at 30-50 rpm, grip it fairly firmly, keep your fingers in the same location on the piece of chalk, and concentrate on the tactile sensations produced by the piece of chalk. After a short period of time, the diameter of the chalk should appear to decrease where it is in contact with the holding fingers.The purpose of this experiment was to investigate the rotating hourglass illusion in the laboratory under more controlled conditions. A tentative theory suggested that adaptation to the sensation of pressure produced by tissue movement was a probable explanation for the illusion. The rate of tissue movement over time is a negatively accelerated function of depth of deformation (Nafe & Wagoner, 1941a). The authors felt that, if the illusion was to be explained by a theory of pressure adaptation of the skin, the study of the time-course of the illusion was important and the rate of rotation of the rod might have an effect on the extent of the illusion. EXPERIMENT I MethodApparatus. To gain better stimulus control, an apparatus was constructed to rotate a rod between S's thumb and forefinger. A *Requests for reprints should be sent to Karen N. Jones, Department of Psychology, University of Oklahoma, Norman, Oklahoma 73069. schematic drawing of this apparatus is shown in Fig. 1. A steel rod (a), 6.35 mm in diam, was mounted in a flat ring (b), 1.86 em wide with an outside diameter of 5.67 em and an inside diameter of 5.60 em. The ring was mounted in three flanged rollers, whieh were tangent to the ring at three plaees around its circumference. Two of the rollers (c) served as idlers; the third roller (d) was driven by a variable-speed motor (e), which could tum the ring containing the rod at a calibrated rpm. S's thumb and forefinger encircled, but did not touch, the ring holding the rod when the thumb and forefinger were in contact with the rod.A schema...

show abstract

“…Recently, a new series of studies reveals a variety of new effects involving this type of judgments, in conjunction with vision [7], complex movements [26], and force cues [88]. In this section we may also include an effect described by Cormack that involves rotating a disk using two passive fingers of one hand and two active fingers from the other [15]. The disk no longer feels round but oval.…”

Section: Kinaesthetic Effectsmentioning

confidence: 99%

A brief taxonomy of tactile illusions and demonstrations that can be done in a hardware store

Hayward

2008

Brain Research Bulletin

139

101

View full text Add to dashboard Cite

This paper surveys more than twenty types of tactile illusions and discusses several of their aspects. These aspects include the ease with which they can be demonstrated and whether they have clear visual analogs. The paper also shows how to construct equipment made of simple supplies able to deliver well controlled tactile signals in order to conveniently demonstrate four different tactile illusions.

show abstract

Haptic Illusion: Apparent Elongation of a Disk Rotated between the Fingers

Cited by 10 publications

References 4 publications

Introducing the shape-length illusion

Introducing the shape-length illusion

A tactile illusion: The rotating hourglass

A brief taxonomy of tactile illusions and demonstrations that can be done in a hardware store

Contact Info

Product

Resources

About