Response Behaviour in the fMRI Experiment

For the fMRI experiment, the paradigm was altered to meet the criteria of fMRI measurements, which was jittering the timings. Further, another stimulus category (animal) was included to disentangle match operations from visual memory and visual model building but also to disentangle the time dependencies across the sequential positions. That means in every series the animal stimuli did appear at a different position within in a sequential position. In a post-measures questionnaire, all participants reported that the animal stimuli did not intrude the identification and learning of the target face. For the fMRI experiment, 6 series were measured, which was half of the number of series of the MEG experiment. For all behaviour measures, 36 participants were respected.

The ANOVA revealed for all response types but the response bias significant main effects of the factor Sequence position (Table 3.4). Considering the effect size, the strongest effect was observed in the HR for match responses (F=21.40, p=6.7*10^-11, Eta²= 0.167), followed by discriminability (F11.26, p=3*10^-6, Eta²=0.133).

The post-hoc analysis of HR for match responses revealed three significant simple effects. These significant simple effects were the first three simple effects, which indicated via the mean HR and the effect sizes an increase from the first to the second sequential positions (1vs2: t=-5.38, p=1.3*10^-5, CoD=0.913) but not further. The subsequent two simple effects (1vs3: F=-5.77, p=0.00015, CoD=1.014; 1vs4: F=-5.88, p=1.1*10^-6, CoD=1.088) were significant and hardly differed in effect size. This could indicate a stabilizing saturation effect of HR across sequential positions. The post-hoc analysis of HR for non-match responses revealed only an increase from the first to the third sequential positions by a significant second simple effect (1vs3: F=-3.10, p=0.0277, CoD=0.430).

Figure 3-4: Behaviour measures of the fMRI study: Hit and response rate, discriminability and response bias, and reaction times. The behaviour measures revealed a positive progress of target identification across the first three sequential positions. A: Hit rates of match responses significantly increased from the first sequential position with a saturation effect beginning at the second sequential position. Hit rates of non- match responses increased significantly from the first to the third sequential positions only. B: The response rates for match and non-match responses followed an opposing trend across the sequential position: The match responses significantly increased while the non-match responses significantly decreased reaching chance level. C: Discriminability significantly increased always compared to the first sequential position. Participants detected the target face better upon a better signal to noise ratio. D: Criterion C values between 0.7 and 0.9 across the sequential position indicated no change in the response bias. Participants remained conservative when responding with ‘Yes’. E: Long reaction times of hit rates of match and non- match responses indicate a difficult task. Only a post-hoc analysis revealed a significant decrease in reaction times of hit rates of match responses. F: Reaction times of response rates significantly decreased from the first to third sequential position for the match responses and when considering overall responses (match and non-match responses together) also from the first and the fourth sequential position. A horizontal line connecting two bars and together with an asterisk indicate a significant post-hoc dependent sample t-test of a simple effect. A vertical line connecting two bars together with an asterisk indicated a significant post- hoc Wilcoxon signed rank test (Red asterisks = p<0.001; Black asterisks = p<0.05). The error-line at each bar represent the standard error. The icons between the panels are described in Figure 3-1.

The post-hoc analysis of RR for match and non-match responses revealed the third simple effect to be significant. The RR for the match responses increased from the first to the last sequential positions (1vs4: F=-3.5, p=0.0078, CoD=0.571), and simultaneously the RR for non-match responses decreased (1vs4: F=3.62, p=0.0055, CoD=0.542). The curse of the mean RR across the sequential positions indicated an increase (match responses) and decrease (non-match responses) to chance level until the fourth sequential position. The post-hoc analysis of the discriminability revealed three significant simple effects. These were the first (1vs2: F= -4.48, p=0.0069, CoD=0.678), the second (1vs3: F=-5.95, p=2.4*10^-6, CoD=0.923) and third simple effect (1vs4: F=-3.61, p=0.0061, CoD=0.585). All revealed an increase across the sequential position. The post-hoc analysis of the response bias indicated no difference in criterion C across the sequential positions. This means that the participants stay on the same level of conservative responses.

Table 3-4: Overview of the test results of the fMRI study for the different response types and reaction times. Repeated measure ANOVA for four different response types and the signal detection theory measures discriminability and response bias. The results are related to effects shown in Figure 3-3. Only between group results are shown. P-values are Bonferroni-Holm corrected.

SS df MS F P-Value Eta²

SS df MS Chi² P-Value Eta²

0.52 3 0.17 21.40 0.0000 0.1669 0.10 3 0.03 4.548 0.0049 0.0332 0.08 3 0.03 5.392 0.0034 0.0421 0.08 3 0.03 5.437 0.0049 0.0382 2.15 3 0.72 11.26 0.0000 0.1326 0.08 3 0.03 1.20 0.3161 0.0161 15.28 3 5.09 9.16 0.0815 0.0849 8.00 3 2.67 4.80 0.3741 0.0444 20.44 3 6.81 12.26 0.0261 0.1136 4.17 3 1.39 2.50 0.4753 0.0231 28.72 3 9.57 17.23 0.0032 0.1596

Response types

Reaction times

Hit rate, ma tch responses Hit rate, non-ma tch responses Ma tch res pons e rate

Nonma tch res pons e rate Hit rate, ma tch responses Hit rate, non-ma tch responses Ma tch res pons e rate

Analysing the RT, the Friedman test revealed two main effects the factor Sequence

position for RT. One main effect was observed for RT regarding RR for match responses

(Chi²=12.26, p=0.0261, Eta²=0.114) and for RT regarding the overall responses (Chi²=17.23, p=0.0032, Eta²=0.160). The post-hoc analysis revealed for both main effects a decrease in RT for the second simple effect and for the overall responses additionally for the third simple effect.