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Article: T actile-Visual Integration and Stereopsis Slotnick, OD, FAAO, FCOVD Samantha “Eyes don’t tell people what they see. People tell eyes what to look for.” This quote by Lawrence MacDonald encap sulates why it is that any two people viewing the same image/object do not necessarily perceive the same thing. Patients with weak binocularity have difficulty integrating information from the two different vantage points of their two eyes. This contributes to difficulty appreciating stereopsis (solid-seeing) based on visual input alone. However, motor experiences provide abundant opportunities to conceptualize depth. Therefore, tactile input can be harnessed in the binocularly-deficient patient as a way to support the development of stereopsis. We all navigate through and interact with a 3-dimensional world, where we are continually encountering solid objects which take up volumes of space. We learn to depend upon feedback from our hands and arms as to the size, weight and texture of objects. We can judge how much force to apply when picking up an object based on its size, volume, material. For example, when picking up a large vase which exceeds the grip of one hand, we will hold it with two hands, so as not to drop it. The hands conform to the curvature of the vase, taking on its shape and dimension. Manipulating the vase provides us with further information about the overall size of the object. Now, imagine you are in the process of redecorating. You carefully pick up this large vase, and you gain knowledge of its mass, size, and how much effort you must apply to maintain your two-hand grip. You place the vase on a shelf, out of the way. Later on, you return to move the vase to a new location. Do you pick it up as tentatively as you did the first time you encountered it? Or do you directly and efficiently lift it, move it, and release it, with minimal assessment? Now let’s add a twist: You have been blindfolded. Your task is to arrange a display of three large vases of different sizes on a shelf which is 2 feet deep and 4 feet wide. The vases differ in height, in maximal girth, and in texture. Sight-unseen, you assess all three, and set about to place them on the shelf in a visually-pleasing distribution. As you handle each vase, you are forming a spatial picture in your mind, and you are assessing relationships between the three. Although blindfolded, this is a visual process. a Correspondence regarding this article should be emailed to Samantha Slotnick, OD at email@example.com. All statements are the authors’ personal opinion and may not reflect the opinions of the College of Optometrists in Vision Development, Vision Development & Rehabilitation or any institution or organization to which the authors may be affiliated. Permission to use reprints of this article must be obtained from the editor. Copyright 2015 College of Optometrists in Vision Development. VDR is indexed in the Directory of Open Access Journals. Online access is available at http://www.covd.org. Slotnick S. Tactile-visual integration and stereopsis. Vision Dev & Rehab 2015;1(4):272-9. Keywords: multi-sensory integration, stereopsis, vision therapy, vision rehabilitation Vision Development & Rehabilitation 272 Volume 1, Issue 4 • December 2015