Experiment 1: Participant Characteristics on the Analysis on Order

VISUAL SEARCH IN ASD 1

Appendix 1

Table 4

Experiment 1: Participant Characteristics on the Analysis on Order

Table 5

Experiment 1: Participant Characteristics on the Analysis on Block Type

Appendix 2

A repeated-measures mixed model analysis with accuracy as dependent variable, Group as between-subject variable, and Instruction, Target Type, Noise and Complexity as within-subject variables, revealed a main effect of Instruction (F(1, 51) = 18.87, p < .0001), Target Type (F(2, 102) = 45.33, p < .0001), Noise (F(1, 51) = 369.12, p < .0001) and Complexity (F(1, 51) = 735.50, p < .0001), as well as a two-way interaction effect of Group x Instruction (F(1, 51) = 6.02, p = .0176) and Target Type x Instruction (F(2, 103) = 19.37, p < .0001), Instruction x Noise (F(1, 52) = 6.46, p = .0141), Target Type x Noise (F(2, 104) = 21.57, p < .0001), Noise x Complexity (F(1, 52) = 140.58, p < .0001). There was no significant main effect of Group (F(1, 51) = 2.44, p = .1247), and no significant two-way interaction effect between Group x Target Type (F(2, 102) = 1.91, p = .1533), Group x Noise (F(1, 51) = .13, p = .7174) , Group x Complexity (F(1, 51) = 0.09, p = .7643), Instruction x Complexity (F(1, 52) = .35, p = .5570), Target Level x Complexity (F(2, 104) = 1.09, p = .3386). The Instruction x Noise (F(1, 52) = 6.46, p = .0141) interaction effect indicated that, while both in the explicit and implicit condition, participants were more accurate in absence of noise, than when noise was present, the difference between noise-absent and noise-present trials was slightly larger in the explicit task conditions, than in the implicit task conditions. The Target Type x Noise (F(2, 104) = 21.57, p < .0001) interaction effect revealed that, while participants were consistently more accurate in absence of noise, the performance difference between noise-absent and noise-present trials, was stronger for trials with global (open or closed) targets, than for trials with local targets. The Noise x Complexity (F(1, 52) = 140.58, p < .0001) interaction effect revealed that, while participants were sensitive to both manipulations of noise and complexity, their performance was more hindered by the noise manipulation, than hindered by the complexity manipulation. Participants scores best in absence of both noise and complexity, and performed the worst when stimuli included noise and target complexity.

A similar repeated-measures mixed model analysis with logRT as dependent variable revealed similar effects: a main effect of Instruction (F(1, 51) = 92.64, p < .0001), Target Type (F(2, 102) = 364.56, p < .0001), Noise (F(1, 51) = 359.99, p < .0001) and Complexity (F(1, 51) = 1192.78, p < .0001), as well as two-way interaction effects of Group x Instruction (F(1, 51) = 11.66, p = .0013) and Target Type x Instruction (F(2, 103) = 8.89, p = .0003), Instruction x Noise (F(1, 52) = 23.98, p < .0001), Target Type x Noise (F(2, 104) = 91.82, p < .0001), Target Level x Complexity (F(2, 104) = 11.86, p < .0001), Noise x Complexity (F(1, 52) = 24.83, p < .0001). There was no significant main effect of Group (F(1, 51) = 2.66, p = .1090), and no significant two-way interaction effect between Group x Target Type (F(2, 102) = .64, p = .5305), Group x Noise (F(1, 51) = 1.41, p = .2411), Group x Complexity (F(1, 51) = 4.87, p = .0319), Instruction x Complexity (F(1, 52) = 3.97, p = .0516). The Instruction x Noise (F(1, 52) = 23.98, p < .0001) interaction effect indicated that, while both in the explicit and implicit condition, participants responded faster in absence of noise, than when noise was present, the difference between noise-absent and noise-present trials was slightly larger in the explicit task conditions, than in the implicit task conditions. The Target Type x Noise (F(2, 104) = 91.82, p < .0001) interaction effect revealed that, while participants were consistently fastest in absence of noise, the performance difference between noise-absent and noise-present trials, was stronger for trials with global (open or closed) targets, than for trials with local targets. The Target Level x Complexity (F(2, 104) = 11.86, p < .0001) interaction effect revealed that, while participants were consistently faster for the easier trials compared to the trials with more complex targets, the precise difference in performance differed depending on the particular type of target. The Noise x Complexity (F(1, 52) = 140.58, p < .0001) interaction effect revealed that, while participants were sensitive to both manipulations of noise and complexity, their performance was more hindered by the noise manipulation, than hindered by the complexity manipulation. Participants were fastest in absence of both noise and complexity, while the largest reaction times were linked to trials where noise was present and target complexity was increased.

Appendix 3

To evaluate possible differential effects of learning in the explicit condition, two additional analyses were performed. In these analyses data from the first 20 trials per Target Type were compared to data from the last 20 trials per Target Type (under the explicit task instruction).

A mixed-model analysis with accuracy as dependent variable, Group as between-subject variable, and Target Type and Test Block as within-subject variables, revealed a main effect of Test Block, F(1, 51) = 6.00, p = .02 and Target Type, F(2, 102) = 19.42, p < .0001. However, none of the following effects was significant: Group, F(1, 51) = .32, p = .57, Group x Test Block, F(1, 51) = .18, p = .68, Group x Target TypeF(2, 102) = 2.12, p = .13, Test Block x Target Type F(2, 102) = 1.56, p = .22, and Group x Target Type x Test BlockF(2, 102) = .44, p = .65. Both groups became slightly more accurate as the task evolved (ME= .90, SDE=.07 vs MI = .92, SDI=.08) but we found no Group x Test Block interaction effect.

A mixed-model analysis with RT as dependent variable, Group as between-subject variable, and Target Type and Test Block as within-subject variables, revealed a main effect of Test Block, F(1, 51) = 23.70, p < .0001 and Target Type, F(2, 102) = 105.63, p < .0001. However, none of the following effects was significant: Group, F(1, 51) = .80, p = .38, Group x Test Block,F(1, 51) = 1.04, p = .31, Group x Target TypeF(2, 102) = .55 p = .58, Test Block x Target Type F(2, 102) = .15, p = .86, and Group x Target Type x Test Block F(2, 102) = 1.36, p = .26. Both groups became faster as the task evolved (ME= 1317, SDE = 332 vs MI = 1205, SDI = 293) but again, we found no Group x Test Block interaction effect.

These additional analyses indicated that while both groups learned in the explicit condition, both in terms of accuracy and reaction time performance, both groups improved their performance in a similar manner.