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AbstractThis paper is an expert review of the current implementation of visual elements on the Target.com home page through the concept of preattentive mechanisms. The paper starts with a description of visual perception and very briefly touches on the concepts of saccadic motion and signal processing that occur in the eye. In order to understand what the purpose of preattentive processing is, the paper goes over relevant biological and psychological research on how the visual sensory system uses preattentive processing to distinguish interesting groupings of elements in the visual field. The paper uses the available research to describe preattentive mechanisms such as constancy, color, relative size, and Gestalt properties including proximity, similarity, alignment, continuity, and closure. This paper will then study the Target.com website, concentrating on elements that stimulate preattentive grouping responses, as well as any distractors. The paper closes with some recommendations for the Target.com site.
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Running Head: PREATTENTIVE PROCESSING AND TARGET.COM 1
Preattentive Processing and Target.com
Armen J. Chakmakjian
Bentley University
PREATTENTIVE PROCESSING AND TARGET.COM 2
Abstract
This paper is an expert review of the current implementation of visual elements on the
Target.com home page through the concept of preattentive mechanisms. The paper starts with a
description of visual perception and very briefly touches on the concepts of saccadic motion and
signal processing that occur in the eye. In order to understand what the purpose of preattentive
processing is, the paper goes over relevant biological and psychological research on how the
visual sensory system uses preattentive processing to distinguish interesting groupings of
elements in the visual field. The paper uses the available research to describe preattentive
mechanisms such as constancy, color, relative size, and Gestalt properties including proximity,
similarity, alignment, continuity, and closure. This paper will then study the Target.com website,
concentrating on elements that stimulate preattentive grouping responses, as well as any
distractors. The paper closes with some recommendations for the Target.com site.
PREATTENTIVE PROCESSING AND TARGET.COM 3
Preattentive Processing and Target.com
Visual perception relies on many stages of processing of signal data before ultimately
being used by higher cognitive functions. (Gazzanina, Ivry, & Mangun, 2002, p. 150) After
detection in the eye, preattentive processing allows the organization of stimulus being sent
through the visual sensory system. (Moore & Egeth, 1997) Preattentive processes involuntarily
and in less than 250 milliseconds signal the presence of a grouping of differences in the
environment confronting a sensory input and are recognized by sensory memory. (Yoo, 2007)
The preattentive mechanism seems to be there to attempt to process items so that they seem to
pop out of the background and allow the observer to choose to attend to them. (Gazzanina, Ivry,
& Mangun, 2002, p. 253). These impressions may be lost if active attention is not triggered,
possibly indicating a near term memory of patterns which informs preattention. (Yoo, 2007)
At the start the paper briefly describes the biological stages of visual sensory processing
including eye movements. In order to understand what the purpose of preattentive processing is,
the paper will go over both the biological and psychological research available in this area and
describes the processing that our visual sensory system uses to distinguish interesting elements in
the visual field. The paper then considers preattentive mechanisms such as constancy, color,
relative size, and Gestalt properties including proximity, similarity, alignment continuity, and
closure. This paper then investigates the use of elements on the Target.com website that stimulate
preattentive responses. The paper closes with some recommendations based on the survey of
research for the Target.com site.
Visual Perception, Gestalt Theory and the Preattentive Mechanism
Visual perception follows the process of visual detection that starts in the eye. Cornsweet
tells us that the eye is in constant motion due to voluntary scanning, involuntary tremors and
saccadic movements. Saccadic movements are drift of the object of focus and the eye’s reaction
to bring that object back to the center of the fovea. (Cornsweet, 1970, 400). Concurrently, the
rods that surround the fovea detect changes in light, and generate a movement called “pro-
saccades” or externally movement triggered towards the sudden appearance of a peripheral
stimulus. (Pierrot-Desilligny, Milea, Muri, 2004).
Once detected, the visual perception system behaves in a way that groups information for
efficient processing through systems called preattentive mechanisms. As Ware points out, the
preattentive mechanisms can be characterized by the Gestalt principles of grouping such as
proximity, similarity, alignment, continuity, and symmetry (as cited in Fekete, van Wilk, Stasko
& North, 2008). Pomerantz makes an argument that color should be accepted as a “psychological
primitive” (Pomerantz, 2006) since it may lead to a pop-out, in other words a signal that
something significant should be attended to in the visual field. Constancy is also thought of as a
preattentive mechanism and one research study points to data that describes how children
PREATTENTIVE PROCESSING AND TARGET.COM 4
generate a preattentive memory of constancy of features (Molholm, Gomes & Ritter, 2001) In
this particular case there are some differences in opinion on whether the affects of constancy
precede or are part of an iterative grouping and processing mechanism. (Palmer, Brooks &
Nelson, 2003). Palmer and Rock argue that preattentive processes are a multi-stage event that
results in a concept of uniform connectedness. (Palmer & Rock, 1994). In their theory,
individually detected and perceived elements are grouped together by subsequent stages that are
both bottom-up Gestalt groupings and informed by pattern memory, indicating involvement of an
involuntary top-down process. (Palmer & Rock, 1994).
This variety of processing implies that biological systems inhibit a significant amount of
information. (Mattingley & Davis, 1997). The next logical question is why did a biological
mechanism evolve in which information is sorted and filtered before attentive processing is done.
Cornsweet posits that because we have a system that can learn, only the stimulus that indicates
change needs to be passed along to higher cognitive processes. Unchanging conditions of the
sensory field are not processed thoroughly since it would be redundant to a learning system.
(Cornsweet, 1970, 443)
Research in Preattentive Mechanisms
In 1966, Beck ran an experiment in which fields of letters in different orientations were
presented to a subject for a short fixed amount of time via a shutter. The experiment found that
grouping by similarity was still possible despite changes in orientation of the letters in the visual
field. (Beck, 1966) Vuilleumier and Landis researched grouping and filling-in in 1997 on patients
with left spatial neglect (they were unable to detect attentively on the left side). In this study it
was shown that contours were perceived without explicit attention, meaning they were handled by
a preattentive mechanism. (Vuilleumier & Landis, 1997) Findings from infant research done by
Quinn, et al, show that 6 to 7 month-olds retain information about the elements presented in the
visual field as well as being able to form larger perceptual groupings such as rows and columns.
(Quinn, Bhatt, Brush, Grimes & Sharpnack, 2002) Later research by Beck, et al, shows that
detection of symmetry is preattentive since subjects’ neural activity was heightened even when
they were not attending to that symmetrical stimulus because a red dot was detected in the
stimulus field. (Beck, Pinsk, Kastner, 2005).
Finally, a 1997 study described a patient that had had a cardiac episode that left him with
normal speech and motor functioning but tests proved that his connection between his
preattentive grouping processes and his spatial attention had been impaired. (Vecera &
Behrmann, 1997, p. 30) The tests showed that for proximity, similarity, and closure that the
patient scored very close to a control subject. However, the patient had significant difficulty with
symmetry and continuity tests. (Vecera & Behrmann, 1997, pp. 39-42) From this research it can
be extrapolated that the brain can still do grouping of visual stimulus in many cases, but this may
PREATTENTIVE PROCESSING AND TARGET.COM 5
indicate that preattentive processing allows it to be more efficient.
Preattentive Processes and the Target.com Website
Today’s e-commerce websites are full of rich, interactive information that convey a sense
of engagement with the user and Target.com is a typical example of this. This paper will analyze
Target.com to see what elements are present that stimulate preattentive mechanisms. The concept
of competition for attention and distraction and the malicious use of preattentive stimulating
elements will also be discussed.
On the left side of figure 1, the top of the landing page of Target.com that was available
on October 14, 2012 is shown. The right side of Figure 1 is skeleton sketch of regions that are
numbered to facilitate this discussion. We will navigate through the regions under 3 basic topics:
The Page Header, The Main Body, and Motion, Distractors and Competition for Attention.
The Page Header
Regions 1, 2 and 3, are the page header. Regions 1 and 2 are separated because the
background colors of white for region 1 and red for region 2 would lead to an obvious discernable
border. The subtle saturation difference in red between regions 2 and 3 would also get processed
preattentively and the fact that regions 2 and 3 are different would get registered. Because these
regions have a color difference, anything inside of those regions would be grouped together under
then mechanism of closure. Adding to this, the text items inside those regions run parallel to the
regional boundaries, the alignment Gestalt mechanism would further imprint grouping on the text
within those regions.
Items 13 and 14 are in these regions also. Item 13 is a search box, in white, inside of
Figure 1: Target.com screen capture (Left) and Skeleton region map (Right)
PREATTENTIVE PROCESSING AND TARGET.COM 6
region 2. While being a normal part of the top of many web pages, and might be a pattern in
pattern memory that is normally grouped in this area of the screen, the color and shape of the
object are distinct enough from the text to achieve pop-out. Item 14 contains the shopping cart
and a number in black in the yellow bubble. Preattentively, this looks like items that are
superimposed on region 3 and while they might satisfy proximity, would pop-out because the
alignment of the cart crosses the boundaries of region 3 at an angle and the yellow bubble would
achieve pop-out since both by shape and color would be different than the contents of region 3.
By the strategic use of yellow here, the most visible color at different levels of luminance, the red
items in the page are grouped together, but the yellow becomes a distractor. Even with the color
difference the cart and bubble might be grouped with each other because of their proximity to
each other.
The Main Page Body
Regions 4 and 5 are long blank white regions without any content. There is no border
between items 4 and 6, but because of the alignment of the blue text in region 6, the preattentive
mechanisms would infer that a different region exists and a border would be filled-in between
them. Similarly, region 5 and the two abutting regions 10 and 9 would be subject to preattentive
filling-in. In this case, regions 5 and 9 are separated from each other with a thin gray line. That
line does not extend upward to separate regions 5 and 10, but preattentively that line would be
drawn to satisfy closure of region 5.
Region 6 is interesting as all the blue text and picture items in the column are in
alignment with each other. This proximity and alignment would allow these items to be grouped
together within that contour. The icons in the lower half of this region, under the title “ways to
save” would also be grouped together because of proximity and similar color and size. However,
this region also has 2 unaligned items superimposed on it. Item 11 corresponds to a picture of the
circular sent to people’s homes. Since item 11 is tipped slightly, it pops out from the column
indicating that although it is proximate to that column it is unaligned and therefore another area
of interest for the user. The item also slightly occludes regions 4 and 7 further indicating
superimposition. Region 12 is superimposed on this column and corresponds to the Target brand
symbol. Because of closure, the concentric circles would be grouped together and since the top of
the circle is apparently occluded by region 3, preattentively the circles would be completed. If the
Target symbol were of interest to the reader, it would have already been processed as the full
symbol should the user wish to selectively attend to it.
The matrix of items in the middle defines region 7. This area might be detected as a
region of rows and columns of red items, all similar. In particular, the items change shape but
each is red and accompanied by similar blue text captions. From a preattentive point of view, this
region of squares would be viewed as a grouping because of similarity of the color red of the
PREATTENTIVE PROCESSING AND TARGET.COM 7
items, the alignment of blue text to each item in a regular pattern and the fact that each one seems
to be in a gray-bordered square. Within that region, one might expect some competition for
attention between the differently shaped items. As one study points out that the arrangement of
products in a list or a table will offer different amounts of competition for attention and that the
tabular form of presentation offers less competition for attention than the list format. (Weiyin,
Thong &Yan, 2004). It might be concluded that this format suppresses the preattentive
mechanism slightly so that the user can have a pleasurable experience searching the site, but this
paper closes with a alternative analysis and recommendation for this area.
Motion, Distraction and Competition for Attention
Region 8, just above region 7, has a gray-blue background, and contains text using 5
different colors and sizes. The dark black letters pop out and may cause them to be grouped
together to also seem to be competing for attention with the rest of the page.
Off to the right of region 7 is region 9, containing a Palmolive advertisement inside a
dark gray box. This indicates a differently shaped region from the matrix next to it. This
advertising region uses different colors than the ubiquitous red and blues of the site. In this case
the Palmolive bottles themselves being placed closely together in the ad would lend to grouping
items there. Further, the Palmolive brand banner appears large at the top of the region, and on the
bottles themselves. Preattentively these banners would signal a grouping based on similarity even
though the sizes of the banners were different.
Finally in region 10, just above regions 8 and 9, there is a revolving banner that updates
every 5 seconds. This area is defined by both the regions that create the perimeter around it, but
also by the motion of the banner. While the rest of the page attentively processed as static, Target
uses motion as a distractor in region 10. Some of the vendors that advertise in region 9 do the
same. In their cases, they are deliberately distracting a user from their current task. For example,
on a refresh of this page a Tide detergent advertisement appears in region 9 that has a significant
amount of motion (not captured in this screenshot).
Recommendations
Target’s website has some problems which will make for a less than engaging user experience.
There are many distractors on the page, even amongst things that might be grouped together
effectively by the preattentive mechanism. This competition for attention can lead to distraction
and anxiety because of the inability of the subject to ignore irrelevant data and would impair task
efficiency or speed of execution. (Derakshan & Eysenck, 2009). In their ubiquitous use of the red
brand color, they have created a lot of visual noise. In particular, since they made red a
background color, the color of action icons, and the color of objects representing different
departments and then further placed them in close grids, all the red starts to become a distractor.
A 1992 study showed that response competition was dependent on the proximity of objects to be
PREATTENTIVE PROCESSING AND TARGET.COM 8
grouped but even more so when the target (in the visual field) and distractor of a similar color
were somehow connected or showed continuity. (Baylis & Driver, 1992). The recommendations
here are to vary the red product icons in the matrix using some other colors and to eliminate the
thin gray line that creates the separating effect of the matrix cells. While we have pointed out
previously that tabular presentation might offer less competition for attention than a list (Weiyin,
Thong &Yan, 2004), given the contents of the grid being the same colors, this may blunt the good
effect of the matrix.
Conclusion
This paper surveyed the relevant research on preattentive mechanisms and their role in
between the physical detection of stimuli by the eye and the later cognitive functions including
attention. The paper explained several mechanisms including Gestalt theory with respect to the
preattentive mechanism and the role of pop out and various types of grouping. The paper
navigated through the Target.com landing page suggesting areas that might stimulate preattentive
grouping and offered a few recommendations to reduce the number of distractors to improve the
page.
PREATTENTIVE PROCESSING AND TARGET.COM 9
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