Path integration refers to the ability to integrate self-motion information to estimate one's current position and orientation relative to the origin. To investigate the effect of active selection in path integration, we used a virtual homing task in which participants traveled along hallways and attempted to directly return to the origin. Two groups of participants differed in the voluntary selection of the path structure, but received the same perceptual and motor information. Information about distance traveled was purely visual via optic flow, whereas turnings were specified both visually and through body senses. The active group made free (Experiment 1) or forced (Experiment 2) selections to determine the structure of the outbound path, whereas the passive group followed these outbound paths. We found no facilitation effects of the active selection on homing performance, suggesting that humans' limited path integration abilities cannot be attributed to the nature of the task.

*piloting*and

*path integration*. Piloting allows navigators to use direct sensory information and landmarks to determine their location and orientation, whereas path integration refers to a phenomenon that navigators integrate information regarding self-motion (e.g., velocity and acceleration information) to estimate their current position and orientation relative to the starting point (Etienne, 1992; Gallistel, 1990; Mittelstaedt & Mittelstaedt, 1982). Information regarding self-motion can be either internal information, such as information from the vestibular, proprioceptive and efferent systems, or external information, such as optic flow.

*path completion tasks*. In this paradigm, human participants travel along several pre-designed segments and then attempt to directly return to the starting point without the aid of direct perceptual cues of the paths. Human participants seldom had opportunity to freely navigate through the environment or voluntarily determine the structure of the paths. Thus, the effects of active exploration on human path integration remain unknown.

*selection*of the paths in path integration. We framed our visual homing task as a “golden apple hunting game” and therefore tested path integration in humans in simulated foraging. In two experiments, one group of participants (active group) navigated in a virtual space to look for golden apples, whereas the other group (passive group) traveled through the paths selected by the active group. Both groups controlled their own movements, including using a game pad to control the translations and physically turning their bodies to achieve the rotations. Thus, the two groups were both physically active and received the same perceptual and motor information, but differed in the voluntary selection of the outbound path structure. Both groups were asked to directly return to the origin of the path upon seeing a golden apple, so their path completion performance was compared to examine the influence of active selection on path integration.

*F*s > 9.57,

*p*< .01). The effect of active selection was marginally significant on the direction errors [

*F*(1, 10) = 3.7,

*p*= .083], but not significant on any other measure (all

*F*s < 1.26,

*p*> .28). The interaction between the active/passive condition and the number of segment was not significant on any measure (all

*F*s < 2.02,

*p*> .13). Planned pair-wise comparisons suggest that no effects of active selection were significant on any measures after Bonferroni corrections for multiple tests (all

*t*s < 2.3, corrected

*p*> .17).

*SD*= 0.78 m), 7.3 m (

*SD*= 0.74 m), 7.4 m (

*SD*= 0.72 m), and 7.4 m (

*SD*= 0.64 m) to be the lengths of the first, second, third, and fourth segments, respectively. The averaged chosen segment length did not change as a function of the number of the segments or the order of appearance of each segment (both

*F*s < 1,

*p*> .41). They also chose an average of 89 deg (

*SD*= 12 deg), 85 deg (

*SD*= 10 deg), and 83 deg (

*SD*= 10 deg) as the turning angles at the first, second, and third intersections, respectively. The averaged chosen turning angle did not change as a function of the number of the intersections or the order of appearance of each intersection (both

*F*s < 2.52,

*p*> .1). As shown in Figure 4, the active group showed a peak at 10 m in length selections and a peak around 90 degrees in turning angle selections, suggesting that the maximum allowable 10-m distance and the right angles (90 degrees) were most frequently chosen when the active group made decisions of their outbound paths.

*F*s > 4.87,

*p*< .01), but neither the RTs nor any of these errors were significantly different between the active and passive conditions (all

*F*s < .79,

*p*> .39). The interaction between the active/passive condition and the number of segment was not significant on any measures (all

*F*s < .84,

*p*> .48). Planned pair-wise comparisons suggest that no effects of active selection were significant on any measures after Bonferroni corrections for multiple tests (all

*t*s < 1.26, corrected

*p*> .92).

*F*s < 1.94,

*p*> .18). Task type influenced RTs [

*F*(1, 20) = 15.56,

*p*< .01], as participants showed longer RTs in the free-choice selection task (3.8 s) than in the forced-choice selection task (2.2 s), but no such effect was significant on any other measure (all

*F*s < .45,

*p*> .51). Path complexity also mattered. When the paths were more complicated (i.e., with more segments), participants showed longer RTs [

*F*(3, 60) = 14.21,

*p*< .01], greater position errors [

*F*(3, 60) = 90.38,

*p*< .01], greater direction errors [

*F*(3, 60) = 54.88,

*p*< .01], and greater distance errors [

*F*(3, 60) = 50.36,

*p*< .01]. The interaction between the number of segments and task was also marginally significant on the RTs [

*F*(3, 60) = 2.69,

*p*= .054] and position errors [

*F*(3, 60) = 2.66,

*p*= .056], but no other interaction effects were significant (all

*F*s < 1.38,

*p*> .26). In addition, we also compared the outbound paths used in two experiments, and found that the total length of the outbound paths used in Experiment 1 was greater than that in Experiment 2 [

*F*(1, 20) = 5.06,

*p*< .05], but the correct homing distance (the Euclidean distance between the starting and ending points of the paths) was comparable in these two experiments [

*F*(1, 20) = .03,

*p*> .86].

*SD*= 1.05 m), 5.3 m (

*SD*= 1.16 m), 5.6 m (

*SD*= 1.01 m), and 5.3 m (

*SD*= 1.01 m) to be the lengths of the first, second, third, and fourth segments, respectively. The averaged chosen segment length did not change as a function of the number of the segments or the order of appearance of each segment (both

*F*s < 2.31,

*p*> .097). They chose 3 m, 5 m, 7 m, and 9 m to be the length of each segment equally often [

*F*(3, 30) = .99,

*p*> .41], but the length they chose for the later segments was influenced by the length they had selected for previous hallway(s) within the same trial. That is, if they chose the length for subsequent segments by chance, the probability that they chose the same length for all the segments within a pathway should be 25%, 6.25%, and 1.56% for 2-, 3-, and 4-segment trials, respectively. However, on 52% of the 2-segment trials, they chose the same length for both segments; on 31% of the 3-segment trials, they chose the same length for all three segments; and on 32% of the 4-segment trials, they chose the same length for all four segments, all of which were greater than chances (all

*t*s > 2.63,

*p*< .05).

*SD*= 10 deg), 71 deg (

*SD*= 12 deg), and 68 deg (

*SD*= 10 deg) as the turning angles at the first, second, and third intersections, respectively. The averaged chosen turning angle did not change as a function of the number of the intersections or the order of appearance of each intersection (both

*F*s < .75,

*p*> .48). They chose 60-degree turns (85%) more often than 120-degree (15%) turns [

*F*(1, 10) = 57.09,

*p*< .01], but chose clockwise and counterclockwise turns equally often [

*F*(1, 10) = 2.81,

*p*= .124]. In addition, the turning angles they selected for the later intersections were also influenced by the turning angles they had selected for previous intersection(s) within the same trial. That is, if they chose the turning angles for subsequent intersections by chance, the probability that they chose the same turning angles (including magnitude and direction) for all the intersections within a pathway should be 25% and 6.25% for 3- and 4-segment trials, respectively. However, on 49% of the 3-segment trials, they chose the same turning angles for both intersections; and on 26% of the 4-segment trials, they chose the same turning angles for all three intersections, both of which were greater than chances (all

*t*s > 3.1,

*p*< .05).

*F*s < .89,

*p*> .40).

*Cataglyphis fortis*. Journal of Comparative Physiology A, 175, 525–530. [CrossRef]

*Cataglyphis*(Formicidae, Hymenoptera). Journal of Comparative Physiology, 142, 315–318.