Description
As a group, males reliably perform better than females in tasks that involve analysis of real or imagined movement, such as mental rotation and targeting. Based upon results from imaging studies during mental rotation performance, the gender differences appear to reflect neural differences related to a bias in the processing of movement versus objects. Such processing for motion and objects occurs within the dorsal and ventral visual streams, respectively. Compared with females, males show greater reliance on unconscious, bottom-up processing of movement within the superior parietal portion of the dorsal stream, with less attention to the details of the object or the environment in which the movement takes place. In contrast, females show greater top-down, conscious analysis of both the object and the environment in which it takes place, which is reflected in greater activation of the prefrontal cortex and inferior temporal lobe. Recent behavioral evidence derived from a computerized task that required participants to estimate the vector of a moving ball indicates that this gender-related processing bias extends to targeting tasks as well. In this task, participants observe a ball moving vertically at various angles from the bottom of the computer screen toward a horizontal line. Before reaching the line, the ball disappears beneath a masking screen. When the invisible ball passes through the line, a paddle appears on the line and participants move it to the estimated point of intersection and click. The present experiments used this same task to test the hypothesis that the gender difference in targeting accuracy could be eliminated by using fast ball speeds and/or small ball sizes. These manipulations reduce a participant's ability to use a top-down analytic strategy, thereby forcing a shift toward bottom-up processing. In the first experiment, targeting accuracy was measured in 15 males and 14 females using six ball speeds (4.6, 5.3, 6.0, 6.9, 7.8 and 8.8 cm/sec) and a large ball. Targeting was tested in an Egocentric Frame of Reference (FoR) where the ball moved vertically up the screen toward the intersect line. Results showed a significant linear improvement in females, but not males, as speed increased. In the second experiment, targeting accuracy was measured in 20 men and 27 women under four ball movement conditions: (1) large ball/slow speed; (2) small ball/slow speed; (3) large ball/fast speed; (4) small ball/fast speed. Participants were tested using both Egocentric and Allocentric FoRs, since the two involve distinct, but overlapping parietal lobe circuitry for motion processing. In the Allocentric FoR, the vertically moving ball is angled to bounce off a side wall before going toward the intersect line. Thus, the relevant vector in the task is between the wall and the intersect line, rather than the body and the intersect line. Results showed that in the Egocentric FoR, male accuracy was significantly better than females in conditions one through three. In the fourth condition (small ball/fast speed), no gender difference was found, showing that the gender difference in targeting performance can be eliminated under conditions that force a strong reliance on bottom-up processing of movement. However, in the Allocentric FoR, male accuracy was significantly better than females in all conditions. The inability of ball size and/or speed to influence gender differences in targeting within an Allocentric FoR suggests that factors other than an attentional bias are involved when a higher order analysis of space relations is required.
