Age Differences in Visual Search for Traffic Signs During a Simulated Conversation 學生：董瑩蟬

Purpose This paper main investigated the age different for search traffic signs. They want to know when at divide attention the subject reaction time, error and eye movement different weather or not. And found the different on the task for younger and older adults.

Reference When search task, the older adults’ eye movement were less systematic. (Maltz and Shinar, 1999) When the signs were large enough, that the older adults’ performance has no different with younger adults. (Ho et al., 2001)

Method Participants –16 younger (M=22.62, range=17-33 years),11F and 5M –16 older (M=64.19, range=56-71 years), 7F and 9M Stimuli and Apparatus –There were 14 regulatory signs and warning signs. The size about 2°, luminance was cd/m2. –The secondary task used four short prose. There were 15 yes/no questions followed each passage

Method Stimuli and Apparatus –Images were presented on a Sony Trinitron Multiscan CPD-100 GS 14-inch (35.6-cm) monitor on a 486 Platform. –Used Eyegaze Development System and Software record manual RT and eye movement. –Used light Velcro head strap to observed maintain viewing distance and gaze angle.

Method Process –The first images was indicated the target present place. –If subject want to start trial, they press the key –There were half trial that the sign present. And half absent. If they respond on the keyboard as soon as possible. –There were 20 trials. –The single-task were given memory test when the subject completing search task.

Method Process –The dual-task completing search task and memory task at the same time. –The experimenter was presenting an audiotaped recording of the prose passages. Subject hearing the passages and responding questions. The older respond correctly that was rewarded. –The subjects workload used NASA-TLX record data.

Method Data collect –Errors, Reaction time, fixation number and average fixation duration. Analysis –Group(2) × Task condition (2, signal or dual) × Clutter (2) × target (2, present or absent) ANOVAs

Result The participants were educated, there were not significant different on formal education. (P=.21; younger=15.25, older=16.38) Used Likert-type scale that found age has on significant different on reported themselves health. (P=0.65; younger=4.14, older=4.21) The younger visual acuity has significant better than older. (P=0.002, younger 20/18, older 20/20) There were significant different between younger and older of driver years. (P<0.001 younger=5.96 older=42.75) The annual distance driven has no significant different on age. (P=0.61; younger=14718, older=13325)

Result-Errors Figure 1. Error rates as a function of attention condition and clutter for target-present (top) and target-absent (bottom) trials for younger (left) and older (right) adults. Rightmost plots indicate significant two-way interactions. Bars are 1 SD.

Result-Errors There were higher error in dual-task F(1,30)=9.41, P=0.005, and in high-clutter scenes F(1,30)=23.36, P< The age has significant different on errors. (F(1,30)=5.33,P=0.03) There was interaction between Age and Present. (F(1,30)=5.3, P=0.028) The older has higher miss sign when sign was present.

Result-reaction time Figure 2. Reaction times as a function of attention condition and clutter for target-present (top) and targetabsent (bottom) trials for younger (left) and older (right) adults. The rightmost plot indicates significant twoway interactions. Bars are 1 SD.

Result-Reaction time The older’ RT was slower than younger. (F(1,30)=25.17, P<0.001) The dual-task has longer RT than single- task. (F(1,30)=11.34,P=0.002) The high-clutter has longer RT than low- clutter. (F(1,30)=34.01, P<0.001) When target-absent, the younger RT was faster than older. (F(1,30)=5.30, P=0.028)

Result-Fixation number Figure 3. Fixation frequency as a function of attention condition and clutter for target-present (top) and targetabsent (bottom) trials for younger (left) and older (right) adults. Rightmost plots indicate significant two-way interactions. Bars are 1 SD.

Result-Fixation number The older has more eye movement than younger. (F(1,30)=15.21, P<0.001) The has more eye movement in high- clutter F(1,30)=73.9, P<0.001, and in target-absent F(1,30)=70.3,P< There was no significant different between signal-task and dual-task. (P=0.25)

Result-Average Fixation duration Figure 4. Average fixation duration as a function of attention condition and clutter for target-present (top) and target-absent (bottom) trials for younger (left) and older (right) adults. The rightmost plot indicates significant two-way interactions. Bars are 1 SD.

Result-Average Fixation duration The older adults has longer average fixation durations. (F(1,30)=11.05, P=0.002) And in high-clutter. (F(1,30)=9.28, P=0.005) And also on target-present trial. (F(1,30)=33.85, P<0.001) There has significant different between Dual- Task and signal-task. (F(1,30)=11.55, P=0.002) There were interaction between Age and task condition. (F(1,30)=9.03, P=0.005) Younger adult has shorter fixation durations in the dual-task.

Result The memory scores was lower in the dual-task. (F(1,30)=84.36, P<0.001) The age was significant different. (P=0.12) The age and task condition has interaction. (F(1,30)=16.29, P<0.001) The signal-task has no different for age (P=0.4). But the dual-task has significant different between younger and older adults (P=0.002). The workload performance has significant different between younger and older adults. (F(1,30)=5.72, P=0.023)

Discussion The secondary task influenced driver performance. (Brookhuis et al.,1991; Strayer et al.,2001) The older adults were slower and less accurate. It has often on search tasks. (Ho et al.,2001) The older adults’ RT and fixation number were longer when target-absent. (Danziger, 1980; Scialfa et al.,2000)

Discussion Like HO et al. (2001) found that older adults has longer RT at clutter. Schieber and Goodspeed (1997) found age and Clutter no interaction at comparable levels of clutter. The divided attention effect older adult’s RT and fixation duration. (Crook et al.,1993; ponds et al.,1988)

Conclusion The older adult has batter performance when at secondary task or clutter task. The older adult RT and fixation number were bad than younger adults. The more errors for older adults. The secondary task effect attention and performance.