Abstract
Esref Armagan is a blind painter. Cognitive and neural scientists have described his use of line structure when drawing and his visual cortex activation during tactile exploration. But what remains unknown is how Esref, without ever having sight, may be able to understand the use of depth cues such as relative size in a picture. To examine whether tactile experience provides information about relative size, we blindfolded sighted individuals and asked them to haptically explore a set of objects in either near or far locations before drawing the objects on paper. Objects explored with an arms extended position were drawn significantly smaller than those explored just in front of the face. Our results provide the first evidence that haptic object interaction can provide information about relative size, akin to that garnered visually. It can be used to inform spatial layout or, in Esref's case, to artistically render objects in three dimensions.
Esref Armagan is arguably the most famous blind painter. He has been the focus of scientific considerations and his paintings have been presented in galleries that span the globe. He has been featured in a media campaign for Volvo. It is compelling to observe Esref's paintings, as they include color-appropriate vistas of land, air, or water. But the real intrigue happens when one considers the extent to which Esref is able to appropriately represent the three-dimensional world in two dimensions.
The situation becomes even more fascinating when one considers that Esref typically paints landscapes. One of his paintings, in particular, is of three windmills on a hillside, each smaller, higher in field, and less detailed than its neighbor down and to the left (Figure 1). Of course, there is life experience—the walking within space, a hillside, and interaction with place, a windmill, that he may draw upon. Kennedy and Juricevic (2006) evaluated Esref's rendering ability in the lab and found his drawings invoked the use of a number of depth cues including line convergence, occlusion, height in the field, and relative size. A case study examining Esref's brain revealed similar patterns of activity during drawing and imagery tasks, patterns that mimic how the visual cortex works during vision and visual imagery tasks in sighted individuals (Amedi, et al., 2015). A number of studies have demonstrated visual cortex activity in blind individuals during tactile exploration, outlining a bona fide alternate route to visual representation (Sathian, 2005).
Armagan's windmills. Photo credit: Joan Eroncel & Esref Armagan.
But perhaps Esref's painting success becomes the most challenging to consider as one realizes that even if a landscape is presented in miniature allowing for haptic exploration, relative size cues are simply not present. If a miniature mock-up of Esref's windmill scene were created, the three windmills would still be the same size. The critical issue to consider is how a person without sight understands the use of relative size in drawing as object form is absolute. That is, the size of an object does not change based on where it lies in space.
For sighted individuals, an object lying in the distance looks smaller than when it is located up close. In situations when tactile information is used in the absence of sight, does a similar experience of relative size emerge? To investigate this idea, I began by simulating life without sight alone in my office, holding up objects at various distances with my eyes closed. I most often ended up holding my glasses, the magnifiers I have come to be so dependent upon of late. And, the two positions I compared most were glasses held just in front of my closed eyes and glasses held at eye level but at arm's length away. In terms of visualization, the imagined size of my glasses changed from flooding my entire visual field to taking up a small percentage of it. But something illuminating happened when I focused on how the glasses felt. They felt larger when they were held in front of my closed eyes compared to when they were held at arm's length—same as they were visualized to be larger when in front of my closed eyes, same as they visually appeared larger in front of my open eyes. The reader can recreate this experience now using any handheld object found nearby.
The next step involved using a between-group design and asking blindfolded, sighted participants to hold different objects either directly in front of their eyes (near condition) or at arm's length (far condition). Ten participants were tested in each of the conditions using common (bowl, stapler, toy-sized football, tennis ball, light bulb) and uncommon (caster wheel, toilet bulb, T pipe fitting, guitar clip, drain pipe elbow) objects. On each trial, there was a brief period of haptic exploration (10–15 s) before the object was taken away and participants rotated to the left, removed their blindfold and were asked to draw the object in the size they felt it to be on graph paper with a.25-inch square grid. To calculate drawing size, the longest horizontal and vertical axes were measured then multiplied to yield area. Objects explored close to the face (M = 526.77, SD = 92.26) were drawn larger than objects explored with arm's extended (M = 355.14, SD = 100.03), t(18) = 3.988, p = .001(Figure 2). The same effect held for common and uncommon objects, demonstrating drawing size to be unrelated to familiarity, common t(18) = 3.416, p = .003, uncommon t(18) = 3.818, p = .001.
(a) Example objects (leftmost) and drawings in near (rightmost) and far (center) conditions. (b) Average area for each object by condition.
It may be surprising that distally held objects feel smaller than those held relatively near but one should consider what it would be like for an object to shrink in visual appearance when it moves to the background but still feel a foreground size. It is possible that participants relied on tacit knowledge, in particular, the use of relative size to represent distance in a drawing, to inform their responses. But they were instructed to draw the objects based on the size each object was felt to be, both familiar and unfamiliar objects revealed the same effect, and we used a between-subject design. It would be difficult to accurately alter the size of an unknown object up or down to capture an effect of relative size without knowledge of actual size and in the absence of a within-subject comparison. The data reveal that information about objects in our visual field, including the angles the objects portend, is available to sensory systems beyond vision providing a viable route to tacit knowledge about the spatial layout of the environment. This finding opens up a series of queries worthy of investigation including tests using stimuli sets that include the same objects across a range of sizes, comparison of size estimates between tactile and visual experience conditions, and evaluation of sighted and blind participants.
Footnotes
Declaration of Conflicting Interests
The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.
Funding
The authors received no financial support for the research, authorship, and/or publication of this article.
