Transcript Visual Search for Traffic Signs: The Effects of Clutter
Visual Search for Traffic Signs: The Effects of Clutter, Luminance, and Aging
Professor: Liu Student: Ruby
References
• The driver needed a greater number of fixations to see the target when the scenes were very confusion. Boersema, Zwaga, and Adams (1988) • The elderly experience change their visual very often when they were effected by the clutter. Kline & Scialfa (1997)
References
• The elderly drivers reduced useful field of view, therefore they make a larger number of eye movements to search a scene. Owsley et al. (1991); Scialfa, Thomas, & Joffe (1994) • The elderly showed cognitive declines that may affect sign obtaining, including problems with working memory and attention. (Caird & Chugh, 1997; Fisk & Warr, 1998; Kidder, Park, Hertzog, & Morrell, 1997; Parasuraman & Nestor, 1991; Plude & Doussard-Roosevelt, 1989; Ponds, Brouwer, & van Wolffelaar, 1988; Stine & Wingfield, 1990)
References
• Older adults are difficulties in low luminance (Chrysler, Danielson, & Kirby, 1996; Kline et al., 1992; Sivak, Olson, & Pastalan, 1981), perhaps because the reductions in retinal illuminance. (Weale, 1961) • The older drive had long response times (RT) in the clutter and different inversely with luminance. Schieber and Goodspeed (1997)
Experiment1
• Objective – The clutter were rated by subjective and allowed for the top-down influences to determine clutter.
• Participants – 14 older adults (
M
= 64.71, range = 56–71 years). – 14 younger adults (
M
= 23.43, range = 20–27 years).
– Daytime was composed of 5 women (4 younger, 1 older) and 9 men (3 younger, 6 older) – Nighttime was composed of 10 women (5 younger, 5 older) and 4 men (2 younger, 2 older).
Experiment1
• The practice trials was composed of 2scenes for each high-clutter and low clutter.
• Participants were instructed to press the “High” key (the
q
key) if they judged the scene to be high clutter and to press the “Low” key (the
p
key) if they judged the scene to be low clutter.
Results
• The 37 images initially presented: – 21 were rated as low clutter. (scores between 0 to 8) – 5 as intermediate clutter. (scores between 8 to 19) – 11 as high clutter. (scores between 19 to 28) • The reliability of the ratings was 0.97.
• Divided reliabilities were 0.97 for the nighttime ratings and 0.91 for the daytime ratings.
Experiment 2
• Objective – Participants search for a target sign which inserted to traffic scenes and related to clutter and luminance.
• Participants – 14 older adults (
M
= 63.93, range = 54–79 years).
– 14 younger adults (
M
= 24.07, range = 18–30 years).
Experiment 2
Procedure
• 10 practice trials that contained both target present and target-absent scenes. (5 were daytime scenes and 5 were nighttime scenes.) • There were two blocks of 25 trials, half the participants searched the 25 daytime scenes first and the 25 nighttime scenes second.
Results
• The analysis of five dependent measures is reported: (a) errors (b) reaction time (c) fixation number (d) average fixation duration (e) fixation duration.
•
Errors
Results -
Errors
Figure 2
. Errors for target-present (top) and target-absent trials (bottom) as a function of clutter and luminance.
Results -
Errors
• Older adults were less accurate than younger ones,
F
(1, 26) = 5.99,
p
=0.021
.
• Errors were more common in high-clutter scenes than in low clutter scenes,
F
(1, 26) = 32.48,
p
< 0.001
and on target-present trials compared with target absent trials,
F
(1, 26) = 6.16,
p
= 0.020.
Results -
Errors
• Interaction – Clutter × Presence effect,
F
(1, 26) = 6.77,
p
= .015
. because more errors were made on target-present trials involving greater clutter.
– Luminance × Presence effect,
F
(1, 26) = 5.67,
p
= .025.
because accuracy for daytime scenes was independent of target presence.
– Clutter × Luminance interaction,
F
(1, 26) = 10.95,
p
= .003.
because in daytime scenes the errors were more common in high clutter than in low clutter.
– Clutter × Presence × Luminance interaction,
F
(1, 26) = 10.79,
p
= .003.
Errors were relatively high in three of the four high-clutter conditions.
Results -
Reaction times
Results -
Reaction times
• The main effects of age,
F
(1, 23) = 27.97,
p
< .001
; clutter,
F
(1, 23) = 570.07,
p
< .001
; and presence,
F
(1, 23) = 49.49,
p
< .001
, were all significant.
• The Age × Presence interaction was also significant,
F
(1, 23) = 7.80,
p
= .01
.
– because age differences were greater on target absent trials than on target present trials.
• Older adults had even slower RTs in the target absent condition than did their younger counterparts,
F
(1, 23) = 10.66,
p
= .003
.
Results -
Fixation number
Results -
Fixation number
• Older adults made more fixations,
F
(1, 23) = 31.89,
p
< .001
.
• Need more fixations for high-clutter,
F
(1, 23) = 60.40,
p
< .001, and for target-absent scenes,
F
(1, 23) = 74.40,
p
< .001
.
• Age × Presence interaction was significant,
F
(1, 23) = 11.53,
p
= .002. • Clutter × Presence,
F
(1, 23) = 12.76,
p
= .002
.
• Nighttime scenes with high clutter also required more fixations,
F
(1, 23) = 9.39,
p
= .005.
Results -
Last fixation duration
Results -
Last fixation duration
• The last fixation duration means the last fixated object with the target representation and the terminal decision (in our case, a key press) regarding target presence.
• The main effect of age was significant,
F
(1, 23) = 13.87,
p
= .001
.
• The main effect of presence,
F
(1, 23) = 23.41,
p
< .001.
• The Age × 8.71,
p
= .007.
Presence interaction was significant,
F
(1, 23) = In contrast with the RT data, age differences were greater on target-present trials than on target absent trials.
Results -
Average fixation duration
Results -
Average fixation duration
• There was a main effect of age,
F
(1, 23) = 11.11,
p
= .003
; clutter,
F
(1, 23) = 130.08,
p
= .001
; and presence,
F
(1, 23) = 49.43,
p
< .001
, in the expected direction.
• Age × Clutter interaction,
F
(1, 23) = 5.76,
p
= .025.
because younger participants showed longer fixations in high-clutter scenes.
• A Clutter × Presence × Luminance interaction,
F
(1, 23) = 9.85,
p
= .005
.
because daytime scenes and high-clutter nighttime scenes including a target resulted in longer average fixation durations.
Discussion
• In Experiment 1 found that observers were able to classify images reliably on the basis of clutter.
• High clutter needed longer fixations to get the sign, which had more errors, and had longer fixation durations.
• Older adults used the visual cues that decided targets and distracters to quickly isolate the target on target-present trials.
Discussion
• The age effects on RT and fixation number were more cleared on target-absent trials.
• Older adults in the present study were not more badly affected when the clutter was increased.
because the definition of clutter.
• The different age groups had differences result in searching daytime and nighttime scenes.