To examine how participants were processing the scenes during and after search, we examined the fixation map similarity
during and
after search and their relationship to search duration. The fixation map similarity during (or after) search was calculated in the same manner (
Figure 2d) but using the individual fixation maps that were generated from the fixations during (or after) search. Regarding the three different fixation map similarity values, we found that the similarity values during and after search were weakly correlated with each other (Pearson's
r(1348) = 0.06 [0.00, 0.11],
p = 0.04) and that the similarity values from the full 8 s data mainly reflected the similarity after search (Pearson's
r = 0.83 [0.82, 0.85],
p < 0.001). The correlation between the similarity from the 8 s and that during search was 0.47 [0.43, 0.51],
p < 0.001. Regarding the relationships between the fixation map similarity and search duration (
Figure 5c), we found that the fixation map similarity during and after search both increased with viewing time (Pearson's
rs = 0.18 [0.13, 0.23] and 0.35 [0.30, 0.39], respectively, both
ps < 0.001), which was either the search duration or free-viewing duration; but the association was stronger in the after-search, free-viewing condition: ANCOVA
F(1, 2930) = 92.54,
p < 0.001). Regarding the relationship between fixation map similarity and scene memory, the fixation map similarity after search, but not that during search, could predict whether a scene would be correctly recognized later (
Figure 5d): AUCs = 0.51 and 0.62,
ps = 0.37 and < 0.001 from permutation testing, for during and after search, respectively. A GLMM analysis (Model S3 in
Table 2; see
Supplementary Table 8 for the full results) confirmed a significant positive effect of fixation map similarity after search on scene memory (β = 0.35 [0.16, 0.55],
p < 0.001) and a nonsignificant effect of fixation map similarity during search (βs = −0.02 [−0.19, 0.14],
p = 0.80). Moreover, the effect of search duration became nonsignificant in Model S3 (
Figure 5b): βs = −0.07 [−1.01, 0.88],
p = 0.89 after adding fixation map similarity during and after search as fixed effects. Together, these results suggest that successful scene encoding happened not during the visual search task but rather after visual search when participants began fixating on memory-relevant regions, providing an explanation to the puzzling negative relationship between search duration and ensuing scene memory.