[accessibleimage] Response 4: Molyneaux's question rephrased

Here, below is another article which strengthens the assertion that touch is
vital for everyone for understanding the world. by The article is "Superior
Performance of Blind Compared With Sighted Individuals on Bimanual
Estimations of Object Size" by Melissa Smith, Elizabeth A. Franz, Susan M.
Joy, and Kirsty Whitehead University of Otago, Dunedin, New Zealand. I think
that everyone, fully sighted and blind people have their primary sense of
the size of things in relationship to their own bodies and their sense of
touch.  If you have already read this article, please excuse the repetition.
But, I have found it relevant to re-read a few times.

Sylvie

Research Report

Superior Performance of Blind Compared With Sighted Individuals on Bimanual
Estimations of Object Size

by Melissa Smith, Elizabeth A. Franz, Susan M. Joy, and Kirsty Whitehead
University of Otago, Dunedin, New Zealand

PSYCHOLOGICAL SCIENCE

Volume 16-Number 1 Copyright r 2005 American Psychological Society 11

Converted from pdf file retrieved from
http://www.psychologicalscience.org/pdf/ps/judging_size.pdf

ABSTRACT-Five preliminary experiments on sighted individuals revealed marked
overestimation on an object size-estimation task using a bimanual response.
These experiments ruled out the possibility that overestimation was due to
the mode of visual presentation (whether two-dimensional or
three-dimensional), the input modality (visual or kinesthetic), or the
influence of other visual cues. The main experiment then investigated
whether these distortions are due to visual experience by using a variant of
the same task to test 24 blind and 24 sighted control participants.
Remarkably, the sighted control participants overestimated object size, on
average, but the blind participants did not. A follow-up experiment
demonstrated that visual memory was the primary influence causing the size
overestimations. We conclude that blind individuals are more accurate than
sighted individuals in representing the size of familiar objects because
they rely on manual representations, which are less influenced by visual
experience than are visual memory representations.

Close your eyes and imagine a familiar object that you see and manipulate
frequently, for example, a loaf of bread. With eyes still closed, indicate
the length of the loaf by the distance between your hands. Without moving
your hands, open your eyes and observe the distance between your hands. Is
this an accu-rate estimation of the length of the bread you imagined? Our
assertion is that, on average, people overestimate size on this type of task
because of biases in their memory representations.

Address correspondence to Liz Franz, Action, Brain, and Cognition
Laboratory, Department of Psychology, University of Otago, Box 56, Dunedin,
New Zealand; e-mail: lfranz@xxxxxxxxxxxxxxxx

The closest variants of this task date as far back as the 1950s, when two
different laboratories examined size perception using visual or nonvisual
judgments. On the basis of the performance of 5 adult subjects on a task
involving size judgments of familiar objects, Bolles and Bailey (1956)
suggested that perception of size comes not only from visual cues, but also
from the past experience that assists one in identifying familiar objects
and therefore their approximate sizes. Bartley, Clifford, and Calvin (1955)
tested 10 blind children and 10 control participants on a task involving
kinesthetic discrimination of the sizes of objects presented in pairs. Their
findings were complicated and mixed, but suggested that the visual and
kinesthetic modalities might result in size judgments that are biased in
different directions, so that in sighted individuals, the two biases cancel
one another to result in reasonably good size judgments. Both studies,
however, used small numbers of subjects and perceptual judgments that did
not indicate the precise size of the object representations held in memory.

More recent research has elucidated direct links between perception and
representation of the size of objects placed at different distances from the
viewer (Kosslyn, 1978; Lockhead & Evans, 1979). These studies indicate that
the same factors that influence visual perception also influence imagery. In
addition, psychophysical methods similar to those used by Bartley et al.
(1955) have shown some differences in the functions that relate actual
object size to memory-based size judgments and perceptually based size
judgments (Moyer, Bradley, Sorenson, Whiting, & Mansfield, 1978).

We were interested in directly measuring people's estimates of object size
in order to investigate internal representations. In a series of five
preliminary experiments, we examined the representation of object size in
neurologically normal, sighted individuals (see results in Table 1). In the
first experiment, 20 undergraduate volunteers were shown 10 familiar grocery
items, each viewed separately from 30 cm away for 6 s. Participants were
then blindfolded and were asked to demonstrate the size of each object when
its name was called out in random order. We observed a marked overestimation
of object size in approximately 70% of the individuals' estimates.

In a second experiment, 20 naive undergraduates were presented with the same
objects in two-dimensional form-each as a picture on an index card. All the
pictures were the same size. Using the same procedures as in the first
experiment, participants overestimated object size to the same degree as
participants in the first experiment.

In a third experiment, a new group of 20 undergraduates were each
blindfolded as they entered our laboratory. They were then presented the
same three-dimensional objects as in the first experiment, and were asked to
touch them with both hands and identify them. Using the same estimation
procedures as before, participants overestimated the size of the objects to
the same degree as in the earlier experiments using visual presentation.

To examine whether overestimation might occur because people are unaware of
where their hands are in space (given that the size estimations in the
previous experiments were performed under blindfolded conditions), in a
fourth experiment we placed small (0.5-cm diameter) light-emitting diodes on
the tips of the index fingers of the participants' hands. We then presented
the objects in the same manner as in the visual-presentation experiments and
conducted the size estimation in a dark booth (without blindfolding the
participants), so that no visual information was available other than the
lights on the fingers. Participants overestimated object size to the same
extent as in the previous experiments, despite being able to see the
distance between their hands.

A fifth experiment examined whether the participants' over-estimation might
be related to responding in unfilled space. Specifically, the perception of
space might be different when one produces a distance between two endpoints
(in this case, the hands) than when one marks a distance on a solid object
contained in that space. We assembled an apparatus that consisted of a piece
of wood (2 in. X 4 in. X 4 ft) with a cover on each end that could be
adjusted to make the exposed piece of wood shorter or longer. Using this
apparatus to respond, participants again overestimated object size following
visual presentation of three-dimensional objects, even with full vision of
their estimates. We therefore concluded that the bi-manual
object-overestimation effect was not due to the mode of visual presentation
(whether two-dimensional or three-dimensional), the input modality (visual
or kinesthetic), or the influence of other visual cues.

TABLE 1

Mean Ratios and Standard Errors for the Preliminary Experiments



Experiment 1 (visual-objects):

Measure:  M: Mean Ratios: 1.20

Measure:  SE: Standard Errors: 0.025

Experiment 2 (visual-pictures):

Measure:  M: Mean Ratios: 1.18

Measure:  SE: Standard Errors: 0.031

Experiment 3 (haptic):

Measure:  M: Mean Ratios: 1.21

Measure:  SE: Standard Errors: 0.033

Experiment 4 (visual-objects, response with LEDs):

Measure:  M: Mean Ratios: 1.19

Measure:  SE: Standard Errors: 0.028

Experiment 5 (visual-objects, response with solid object):

Measure:  M: Mean Ratios: 1.10

Measure:  SE: Standard Errors: 0.040


Measure:  M: Mean Ratios

Experiment 1 (visual-objects):  1.20

Experiment 2 (visual-pictures):  1.18

Experiment 3 (haptic):  1.21

Experiment 4 (visual-objects, response with LEDs):  1.19

Experiment 5 (visual-objects, response with solid object):  1.10

Measure:  SE: Standard Errors

Experiment 1 (visual-objects):  0.025

Experiment 2 (visual-pictures):  0.031

Experiment 3 (haptic):  0.033

Experiment 4 (visual-objects, response with LEDs):  0.028

Experiment 5 (visual-objects, response with solid object):  0.040

Note. As indicated, the experiments varied in whether the objects were
presented visually (as three-dimensional objects or two-dimensional
pictures) or haptically. In the first through fourth experiments, subjects
estimated size by their hand span; they were blindfolded in the first three
experiments but in the fourth were in a dark room and could see LEDs on
their fingertips. In the fifth experiment, subjects were blindfolded while
estimating size using a block of wood. The ratios reported were calculated
by dividing subjects' estimates by the corresponding actual measures of the
objects and averaging across objects and subjects. All t tests assessing
deviations of mean ratios from 1.00 were significant, including those for
size estimates on the initial trial of each object (all ps < .05).

From these preliminary experiments, it was clear to us that sighted
individuals, when asked to perform object estimations from memory, tend to
overestimate the size of objects that are frequently seen and manipulated in
the space around the body (peripersonal space). We were curious whether this
effect is due, at least in part, to frequent visual experience with the
world. Specifically, sighted individuals see objects every day in different
orientations, from different distances, and in the context of a variety of
everyday uses. Moreover, somehow a memorial representation of these objects
is maintained, evidenced by the ability to readily imagine them. In
contrast, people who have been blind for some portion of their recent life
experience (or all of their lives) would have had to rely on manual rather
than visual representations. It might be that without visual experience,
memorial representations are more accurate. Note that it could also be
argued that the blind often reach for remembered objects without immediate
guidance from a distal sense, and they may therefore have developed good
manual size estimates.

Another possibility is that the overestimations of object size in sighted
individuals are due not to visual experience, but rather to general
properties of the manual response system. For example, studies on uni-manual
grasping have shown that just prior to reaching an object, the grasp
aperture is larger than the object itself (Jeannerod, 1981). Similar
properties tend to describe bimanual and unimanual grasping (Tresilian &
Stelmach, 1997). In some ways, producing a grasp aperture that is larger
than the object to be grasped might be a mechanism to ensure that a
successful grasp eventually occurs, because the aperture becomes smaller as
the object is approached. Although our participants were asked not to grasp
objects but only to demonstrate their sizes, this task itself might elicit a
representation of grasp aperture. By M. Smith et al.

this account, we would expect sighted and blind individuals to demonstrate
the same degree of size overestimation on our task, given that there is no
reason to suspect that the manual response systems operate any differently
in the two groups.

METHOD

Participants

Twenty-four blind adults recruited from the Royal New Zealand Foundation for
the Blind volunteered to be participants after informed consent was obtained
in accordance with ethical procedures of the University of Otago. Of these
participants, 9 were classified as congenitally blind, having lost their
vision within the first 3 years of life (Thinus-Blanc & Gaunet, 1997). The
remaining participants were classified as adventitiously blind. A control
subject was matched to each blind subject for sex, education, and age (to
within 2 years). None of the control subjects had any known neurological
disorder, and all had normal or corrected vision.

Apparatus

A millimeter tape was used to measure the distance between the participants'
hands. A blindfold was used to block vision. The objects whose sizes were
estimated were common grocery items, categorized as either vertically or
horizontally oriented on the basis of whether the horizontal or vertical
dimension was larger in the object's commonly observed orientation. The five
vertical objects, ranging in height from 62 mm to 345 mm, were a 2-L jug of
milk, 750-g box of crackers, standard can of vegetables, standard can of
soda, and 150-g container of yogurt. The five horizontal objects, ranging in
length from 119 mm to 300 mm on their longest side, were a standard loaf of
bread, carton of a dozen eggs, 500-g package of long spaghetti, 500-g
container of butter, and standard candy bar. No interesting effects
differentiated the objects within each set; therefore, data were collapsed
across objects.

Procedure and Design

Participants (both sighted and blind) were blindfolded through-out the
procedure and were instructed to manipulate each of 10 objects for 6 s using
both hands. To ensure that all items were familiar, we asked participants to
report the identity of each object and how often they purchased and used it.
If the item was not familiar to the subject, it was replaced with another
that was (e.g., a package of spaghetti was replaced with a block of cheese).
Such replacement occurred for 6 objects in total, across all subjects (and
all analyses indicated that the re-placement was inconsequential to the
overall effects). After all 10 objects were presented (in random order
across subjects), the measurement phase began.

During the measurement phase, the experimenter called out an object name at
random from the group of possible objects.

The participant then bi-manually estimated the dominant dimension of the
object by indicating a hand span, holding the hands in a rigid posture
extending from the bent elbows. The distance between the index fingers of
the participant's out-stretched hands was measured in millimeters. These
procedures were repeated until each object was tested 10 times. Between
trials, participants were asked to place their hands on their laps, but no
feedback was given. For a subsample of the subjects, responses on all trials
were also recorded using videotape and then measured off-line. The
measurements from the videotapes (adjusted for viewing distance) correlated
with the actual measurements from the experimenter with 90% reliability.

Data Reduction

A check was first made to ensure that estimates of object size were
proportional to actual object size. We measured the length of each
horizontal object and the height of each vertical object to produce 10
standard measures. We then computed a correlation coefficient between
estimated and actual object size across all trials for each participant. For
the blind group, these values ranged from .78 to .99 (M 5 .92), and for the
control group, the range was .89 to .98 (M 5 .94). We then transformed the
correlation coefficients to Z scores using a Fisher transform and conducted
an independent t test to assess any group differences in the transformed
correlations. The t test was not significant, t(46) 5 0.44, p> .05.

We divided each recorded measure from the raw data by its corresponding
standard measure to produce a ratio for each trial. A ratio of 1 indicated
that the size estimate was exactly the same as the standard. A number larger
than 1 indicated an overestimation, and a number smaller than 1 indicated an
underestimation.

Two analyses were performed on the ratios. First, one-way t tests assessed
whether the ratios were significantly different from 1 (i.e., whether
participants' estimates were under or over the real object size). Second, we
conducted mixed-effects analyses of variance with the between-subjects
factor of group (blind, sighted) and the within-subjects factor of
orientation (vertical, horizontal).

RESULTS AND DISCUSSION

The blind group's estimates of object size were not different from the
standard measures, t(23) 5 1.008, p 5 .32. In contrast, the sighted
individuals produced overestimations that were significantly larger than the
standard, t(23) 5 8.52, p < .001. The means and standard errors of the
ratios for the two groups are shown in Figure 1. A highly significant effect
of group was found, F(1, 46) 5 10.60, p 5 .002. Note that the two groups
also differed on the first trial of each object, so carryover effects of
repetition were not responsible for the group differences, t(46) 5 -2.60, p
5 .013, Cohen's d 5 0.75. These findings indicate that compared with the
sighted control group, the blind group produced estimations that were
closer, on average, to the actual sizes of objects.

Fig. 1. Means and standard errors of the ratios for the blind and sighted
(''Sighted-'') groups in the main experiment and the sighted (''Sighted1'')
group in the follow-up experiment. In the follow-up experiment, subjects
could view the object while estimating its size, which removed the visual
memory requirement.


At the end of the experiment, each participant was queried about any
strategies he or she used. Interestingly, 50% of the blind group used a
strategy of imagining holding the object. The most frequently reported
strategy among the sighted was to imagine the object's size in relation to
the size of a body part (see Table 2).

We reasoned that the group differences would be more compelling if at least
some aspect of the task was performed similarly across the two groups. For
example, performance might be better for horizontally than for vertically
aligned objects because the mirror-image symmetry of the body would allow
for better distance judgments in the horizontal than in the vertical
orientation. If so, this should be the case for both groups. This prediction
was supported, with overestimation being lower overall for horizontal
objects (mean ratio 5 1.08) than for ver-tical objects (mean ratio 5 1.18),
F(1, 46) 5 17.31, p < .001; orientation did not interact with group, F(1,
46) 5 1.152, p 5 .29. This result suggests that the structural symmetry of
the bimanual system benefited the two groups to a similar degree.

TABLE 2

Strategies Used by Each Group

Group:  Blind
Strategy:  Imagine holding the object
Percentage of subjects:   50

Strategy:  Try visualizing the object
Percentage of subjects:   29 a.

Strategy:  Imagine body parts as a comparison standard
Percentage of subjects:   13

Strategy:  No particular strategy used
Percentage of subjects:  8

Group:  Sighted

Strategy:  Imagine holding the object
Percentage of subjects:  13

Strategy:  Try visualizing the object
Percentage of subjects:   8

Strategy:  Imagine body parts as a comparison standard
Percentage of subjects:  38

Strategy:  No particular strategy used
Percentage of subjects:  41

Note a. Two of these individuals were blind from birth.

We tested an additional 20 (naive) sighted control subjects on a version of
the task that allowed them to see the objects but not their hands during the
size estimations. On each trial, the object was placed directly in front of
the subject on a small shelf (30 cm away) that obstructed the subject's view
of her or his hands while keeping the object in clear view. We then
conducted the size-estimation procedures. Under these conditions, there was
no tendency to overestimate ( p > .05). Thus, when we removed the visual
memory requirement by allowing sighted participants to demonstrate size with
each object in full vision, the tendency to overestimate was significantly
reduced.

In summary, these findings support our novel hypothesis that the memory
representations of sighted individuals overestimate object size unless
visual memory demands are relaxed. The memory representations of people who
have lost vision for some portion of their lives are less likely to
overestimate object size, suggesting that blind people may have developed
accurate haptic size representations in support of reaching and grasping
actions.

Acknowledgments-This research was supported by Otago Research Grant MFUB26
to Liz Franz. We are grateful to the Royal New Zealand Foundation for the
Blind for their invaluable assistance in recruiting participants, the
participants for their generous contributions of time and effort, and John
Kennedy and an anonymous reviewer for very instructive suggestions during
the review process.


REFERENCES

Bartley, S.H., Clifford, L.T., & Calvin, A.D. (1955). Effect of visual
imagery on tactual and kinesthetic space perception. Perceptual and Motor
Skills, 5, 177-184.

Bolles, R.C., & Bailey, D.E. (1956). Importance of object recognition in
size constancy. Journal of Experimental Psychology, 51, 222-225. Jeannerod,
M. (1981). Intersegmental coordination during reaching at natural visual
objects. In J. Long & J. Baddeley (Eds.), Attention and performance IX (pp.
153-169). Hillsdale, NJ: Erlbaum.

Kosslyn, S. (1978). Measuring the visual angle of the mind's eye. Cognitive
Psychology, 10, 356-389.

Lockhead, G., & Evans, N. (1979). Emmert's imaginal law. Bulletin of the
Psychonomic Society, 13(2), 114-116.

Moyer, R., Bradley, D., Sorenson, M., Whiting, J., & Mansfield, D. (1978).
Psychophysical functions for perceived and remembered size. Science, 200,
330-332.

Thinus-Blanc, C., & Gaunet, F. (1997). Representation of space in blind
persons: Vision as a spatial sense? Psychological Bulletin, 121(1), 20-42.

Tresilian, J., & Stelmach, G. (1997). Common organization for uni-manual and
bimanual reach-to-grasp tasks. Experimental Brain Research, 115, 283-299.

(RECEIVED 10/28/03; REVISION ACCEPTED 12/16/03)


----- Original Message ----- 
From: "Lisa Yayla" <fnugg@xxxxxxxxx>
To: <accessibleimage@xxxxxxxxxxxxx>; "Art Beyond Sight Theory and Research"
<art_beyond_sight_theory_and_research@xxxxxxxxxx>
Sent: Sunday, September 03, 2006 6:29 AM
Subject: [accessibleimage] Molyneaux's question rephrased


Hi,
Following are some questions I have about touch and sight. Would
appreciate any feedback, thoughts

In the paper "Recovery from Early Blindness" by Richard Gregory he
describes a man, S.B, gaining vision at the age of 51. Shortly after the
operation he draws pictures from what Gregory calls "touch memory" and
is able to understand objects through vision alone and not touching
them, though they are objects he has known from touch when blind (clock
on wall and written letters). This again touch memory. In his pictures
though he does not enter features which he "had not known previously by
touch".

This seems to answer differently than John Locke's answer to Molyneaux

However S.B had difficulty recognizing faces and facial expressions.
This is also the case for Michael May (blind and regained sight) that he
has difficulty with understanding faces and facial expressions. I was
thinking that perhaps the explanation to this is that facial
expressions, body language are something done "on the fly", there is
movement involved and this is something one can not experience with
touch. Transition of expression involves movement.

In lieu of this would it not seem fair to rephrase Molyneaux problem to:

"If a blind person gains sight will that person, soon after gaining
sight, understand an object from sight alone not having experienced it
by touch from before?"

and/or Could this be compared to an archaeologist who uncovers an object
and doesn't know what it is?

The idea being that touch is very important for sight

Is perhaps sight  the "servant" of touch? That sight discovers things
for us to touch? The original object of development is to touch and
verify?  Is sight the ability to "touch" at a distance? That sight
develops from touch? Sight developed to be able to touch farther away
then the lengths of our arms?

Thanks,
Lisa


http://www.richardgregory.org/

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