The position selection and timing data were analyzed separately, with the former analysis being based on the normalized frequency data. All analyses of variance (ANOVAs) below report the partial eta-squared (η
2) statistic, which describes the proportion of total variability attributable to the particular factor (Olejnik & Algina, 2003). Huynh–Feldt adjustments were used on the probabilities, where necessary, and all post hoc pairwise comparisons included Bonferroni adjustments and were measured as significant at the p < .05 level.
Pop-out displays: how often do hiders and seekers select the unique item?
To investigate whether selection was biased toward visually unique items, we analyzed pop-out trials,Footnote 2 calculating the relative frequency with which the unique item was selected. The data were split by task type (hide or seek) and partner type (friend or foe). The group means are shown in Fig. 2.
We found a main effect of partner type [F(1, 30) = 87.187, p < .001, η
2 = .744]: The unique item was selected more frequently on friend than on foe trials (.726 vs. .071). No other effects were significant (all ps > .1).
Homogeneous displays: are some spatial positions selected more often than others?
To investigate item selection in the absence of visual biases, we analyzed which items were selected on homogeneous displays.
Near versus far
Reaching for closer items required less effort and energy than does reaching for items at the back of the display. Would such “embodied” considerations have an impact on the locations selected when hiding and finding for a friend or a foe?
We collapsed item selections across the four items in each row, collapsing further the top two and bottom two rows. These data are shown in Fig. 3, from which an overall bias is clear toward participants selecting items closer to themselves. One-sample t tests indicated that the relative frequencies of selecting bottom items were above chance (.5) for all conditions (all ps < .01). A mixed-design, two-factor ANOVA (Partner × Task Type) revealed a main effect of partner type, F(1, 30) = 4.741, p = .037, η
2 = .136), so that participants were more likely to select items closer to themselves on friend than on foe trials (.836 vs. .704). No other effects were significant (all ps > .4).
Center versus corners
Past studies have revealed a tendency to attend, look, and reach toward the middle of displays (e.g., Prime & Marotta, 2013). We compared the numbers of times the center four items were chosen with the numbers of times the four corner items were chosen (see Fig. 4). A three-factor ANOVA (on task type, partner type, and item position) indicated main effects of item position [center vs. corner: F(1, 30) = 9.875, p = .004, η
2 = .248], partner type [friend vs. foe: F(1, 30) = 4.535, p = .042, η
2 = .131], and task type [hide vs. seek: F(1, 30) = 5.742, p = .023, η
2 = .161]. Items in the corner were more likely to be selected than central items (.352 vs. .189), whereas the selection of both types of items was increased on friend as compared with foe trials (.316 vs. .225), and was increased on hide as compared with seek trials (.302 vs. .239). We also found a Partner Type × Item Position interaction [F(1, 30) = 29.209, p < .001, η
2 = .493]: Corner items were more likely to be chosen on friend than on foe trials (a difference of .329, p < .001), whereas central items were more likely to be chosen on foe than on friend trials (a difference of .165, p = .002). No other effects were significant (all ps > .05).
Do the times taken to hide and seek differ?
The time from the start of the trial until participants had selected an item was recorded (completion time). Median completion times were calculated for each participant within each condition (display type + type of partner) and split by task type (hiding, seeking). The group means are shown in Fig. 5.
On trials with no unique items, a borderline interaction emerged between partner type and task type [F(1, 30) = 3.941, p = .056, η
2 = .116]. When hiding, no difference was observable between friend and foe (p = .719), but when seeking, a difference of 268 ms emerged (p = .017). No other main effects or comparisons were significant (all ps > .1).
A main effect of partner type was apparent [F(1, 30) = 8.124, p = .009, η
2 = .213], in which responses were longer for foes than for friends (1,129 vs. 980 ms), as well as an interaction [Task Type × Partner: F(1, 30) = 7.299, p = .011, η
2 = .196]. The interaction was driven by hiding a target for a foe taking far longer than both hiding a target for a friend (290 ms, p = .001) and seeking an item hidden by a foe (a difference of 290 ms, p = .031). No other comparison reached significance (all ps > .9).