# Visual and Haptic Guidance for Enhancing Target Search Performance in Dual-Task Settings
## 3 Study 1: Visual Guidance Design and Evaluation
### Results
#### 3.2.1 Selection Time and User Behavior Data in Primary Task of Study 1  
Selection Time The definition of selection time varied, based on the nature of the preceding selection task. If the previous selection task was the same Primary Task, with the target in front of the participant, we defined the selection time as the interval fromwhen the target (denoted by the letter \"P\") appeared to the successful completion of the selection. Alternatively, if the preceding selection task was a Secondary Task, with the target positioned behind the participant, we needed to adjust the start point of the selection time as users needed time to turn their head forward again. We took into account that the human central visual field's typical span of a 60\({}^{\circ}\) diameter [62], and all targets of the Primary Task were within this region. Therefore, we measured the selection time from when the participant adjusted their head to a direction 30 degrees from the forward direction up to the successful execution of the selection. Main effects were found for Arrow \((F_{1,11}=7.78,p<0.05)\), Row \((F_{2,23,24.51}=11.72,p<0.001)\), and Column \((F_{4,44}=15.25,p<0.001)\). (The sphericity assumption was not met so the Greenhouse-Geisser correction was applied; the corrected degrees of freedom are shown.) The mean selection times across Arrow Type, Visual Guidance Continuity, Row, and Column are illustrated in Figure 2a. Post hoc Bonferroni pairwise comparisons showed that the selection time with the Dynamic Arrow (2.73 s) was significantly faster than that with the Static Arrow (2.87 s) \((p<0.05)\). The selection time of row 1 (3.05 s) was significantly longer than those of row 2 (2.58 s) \((p<0.001)\), row 3 (2.65 s) \((p<0.01)\), and row 4 (2.62 s) \((p<0.05)\); row 5 (3.08 s) was significantly longer than row 2 (2.58 s) \((p<0.05)\), row 3 (2.65 s), \((p<0.01)\) and row 4 (2.62 s) \((p<0.01)\). The selection time of column 2 (2.65 s) was significantly faster than that of column 1 (2.94 s) \((p<0.05)\) and column 5 (3.13 s) \((p<0.001)\); column 3 (2.54 s) was significantly faster than column 1 (2.94 s) \((p<0.05)\), column 4 (2.73 s) \((p<0.01)\), and column 5 (3.13 s) \((p<0.001)\); column 4 (2.73 s) was significantly faster than column 5 (3.13 s) \((p<0.05)\). Head Rotation Angle We recorded the total head rotation angle during the selection time. Main effects were found for Row \((F_{2,37,26.05}=8.88,p<0.01)\) and Column \((F_{4,44}=7.75,p<0.001)\). (The sphericity assumption was not met so the Greenhouse-Geisser correction was applied; the corrected degrees of freedom are shown.) No other main or interaction effect was found. The mean head rotation angles across Arrow Type, Visual Guidance Continuity, Row, and Column are illustrated in Figure 2b. Post hoc Bonferroni pairwise comparisons showed that the head rotation angle of row 1 (83.80 degrees) was significantly longer than those of row 2 (62.99 degrees) \((p<0.001)\) and row 3 (68.06 degrees) \((p<0.01)\), and that row 5 (84.36 degrees) was significantly longer than row 3 (68.06 degrees) \((p<0.01)\) and row 4 (68.48 degrees) \((p<0.05)\). Head Movement Distance We recorded the total head movement distance during the selection time. Main effects were found for Row \((F_{4,44}=9.19,p<0.001)\) and Column \((F_{4,44}=4.71,p<0.05)\). The mean head total movement distances across Arrow Type, Visual Guidance Continuity, Row, and Column are illustrated in Figure 2c. Post hoc Bonferroni pairwise comparisons showed that the distance of row 1 (17.20 cm) was significantly longer than those of row 2 (13.40 cm) \((p<0.001)\), row 3 (14.16 cm) \((p<0.01)\), and row 4 (14.13 cm) \((p<0.05)\), and row 5 (16.72 cm) was significantly longer than two 4 (14.13 cm) \((p<0.05)\). The distance of column 5 (16.82 cm) was significantly longer than those of column 2 (14.31 cm) and column 3 (14.12 cm) \((p<0.05)\). We also recorded the head movement distance along the X, Y, and Z dimensions.