Display Characteristics that Support
Aided Symbol Use:
Should Symbols that Share a Color Be
Clustered Together or Placed Apart?
Krista M. Wilkinson, Ph.D.
Vinoth Jagaroo, Ph.D.
Emerson College
ASHA Convention, 2007
Funded in part by ASH Foundation New Century Scholar Award, 2006
Rationale
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Because vision is the input and output channel for many users of aided
AAC, understanding visual processing is as critical to its success as the
understanding of auditory processing is to aural-oral interventions.
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Aided AAC displays require placement of symbols on a physically limited
space. For each message, the user must search through the array to find
the desired symbol.
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The effectiveness of aided displays depends in part on the efficiency with
which the visual information can be processed by the user.
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Yet virtually no research has been conducted on visual processing in
children who are likely users of aided AAC or on aided AAC itself. Thus,
clinicians are left to make decisions about display construction in the
absence of an evidence base to guide them. This research initiates study
of visual processing as it relates to aided AAC.
Why color?
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Basic science in human perception
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•
•
•
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Color enhances basic perception,
Identification,
Recall, and
Categorization of stimuli
Clinical AAC
•
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Readily available software programs allow addition and alteration of color
Decisions are made on a daily basis concerning color
Do color cues affect performance?
Wilkinson, Carlin, & Jagaroo, 2006 (typical children only)
“same”
Slowest & least accurate responses:
Target =
Fastest & most accurate responses (both conditions):
“mixed”
“unique”
How should we arrange symbols?
Wilkinson, Carlin, & Thistle, in press
distributed throughout the array…
clustered together within the array…
Methods
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•
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8 younger typically developing (TD < 4 yrs)
8 older typically developing (TD >4 yrs)
7 individuals with Down Syndrome
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Vocabulary matched to the older TD children
pre-assessment: stimuli first presented individually,
then auditory-visual match to sample task with 4
choices of the same color.
“tomato”
“broccoli”
Experimental Task/Conditions
Clustered
Distributed
banana
CLUS
DIST
Results
Mean accuracy (higher = better)
Median Reaction Time
(lower = better/faster)
100%
4
95%
3.5
3
90%
2.5
85%
2
80%
Younger children
Older children
Children with DS
1.5
Younger children Older children
Children with DS
This pattern of results was identical across all stimulus
types (foods, clothes, activities)
Implications
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Symbol-internal color cuing has a clear effect on reaction time (in
all groups) and accuracy (in individuals with DS) during search for
a target in an array, for all stimulus types.
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It would seem from these results that clustering symbols that
share an internal color facilitates search, creating a mini-array
within which to search.
•
Future directions
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•
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Assessment protocol
Autism and other etiologic categories
Displays of different sizes
Relation of foreground to background color
The Effects of Background Color on
Speed of Locating a Symbol:
Implications for AAC Display Design
Jennifer Thistle
Master’s Thesis
ASHA Convention
Funded in part by Emerson College Student Research Funding Award, 2007
Color Encoding
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Using background color to encode different
parts of speech (Goossens’, Crain, & Elder, 1999)
Primary Research Question
What is the role of color cues on the speed with
which children locate a target in an array?
Related Research Questions
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What is the effect on reaction time when the
color cue is internal to the symbol (colored
symbol on a white background) as opposed to
when the color cue is on the background of
the symbol (white symbol on a colored
background)?
Related Research Questions
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What is the effect of a background color
match or mismatch to symbol identity (i.e., red
background or blue background of a
watermelon symbol)?
Related Research Questions
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When given an internal color cue (red
watermelon), what is the effect of adding an
additional background color cue as well (blue
background)?
Related Research Questions
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What are the age-related effects in each of the
above?
Methods
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21 typically developing preschool children, 3;0
to 5;4 years old.
10 younger; 11 older
pre-assessment: stimuli first presented
individually, then auditory-visual match to
sample task with 4 choices of the same color.
Conditions
–
Colored symbol, white
background
–
White symbol, associative color
background
–
White symbol, non-associative
color background
–
Colored symbol, nonassociative color background
Results
5
4.5
Foreground
4
Bac k 1
Mean Latency in Seconds
3.5
Bac k 2
3
Both
2.5
2
1.5
1
A v erage Y ounger
A v erage Older
Child Group
Implications
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Age differences
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When provided with both internal and background color, the
background does not significantly distract
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AAC design and use of background color
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Word order/sentence structure
Learning symbol and symbol location
Future research
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Assessment protocol
Other populations
“Best” colors to use in color coding
Questions