Evidence for an error deadzone in compensatory tracking

Humans and monkeys show intermittent arm movements while tracking moving targets. This intermittency has been explained by postulating either a psychological refractory period after each movement and/or an error deadzone, an area surrounding the target within which movements are not initiated. We present a technique to detect and quantify the size of this deadzone, using a compensatory tracking paradigm that distinguishes it from a psychological refractory period. An artificial deadzone of variable size was added around a visual target displayed on a computer screen. While the subject was within this area, he received visual feedback that showed him to be directly on target. The presence of this artificial deadzone could affect tracking performance only if it exceeded the size of his intrinsic deadzone. Therefore, the size of artificial deadzone at which performance began to be affected revealed the size of the intrinsic deadzone. Measured at the subjects' eye, the deadzone was found to vary between 0.06 and 0.38 degrees, depending on the tracking task and viewing conditions; on the screen, this range was 1.3 mm to 3.3 mm. It increased with increasing speed of the target, with increasing viewing distance, and when the amplitude of the movement required was reduced. However, the deadzone size was not significantly correlated with the subjects' level of performance. We conclude that an intrinsic deadzone exists during compensatory tracking, and we suggest that its size is set by a cognitive process not simply related to the difficulty of the tracking task.     

Backward walking: a simple reversal of forward walking?

The purpose of this study was to determine whether backward walking represented a simple temporal reversal of forward walking and, hence, could be controlled by a reversed cycling of the same group of neurons. Electromyographic (EMG), joint angle, joint moment, and joint muscle power patterns were compared for forward and backward walking, in 6 subjects. The joint angle patterns with the time-base of the backward walking reversed were similar, with the exception of the ankle. The moment patterns were similar except for the knee, whereas the joint muscle powers were almost reversed-polarity images of each other. This suggests that somewhat similar muscle activation patterns could be used to produce both modes of locomotion, but the temporal cycling of muscle contraction would be reversed: Concentric muscle activity in forward walking would become eccentric activity in backward walking, and visa versa. The EMG results generally supported these findings.     

Infants’ identification of three-dimensional form from transformations of linear perspective

The ability of infants to perceive three-dimensional structure from transformations of linear perspective was investigated in two studies. Infants were habituated to the pattern of linear perspective transformations corresponding to a particular three-dimensional object, and their relative preference for that object as compared with a different three-dimensional object was assessed both before and after habituation. The habituation displays showed the distorting shadow cast by a rotating object and therefore provided only transformations of linear perspective as information specifying three-dimensional form. The pre- and posttest displays involved the actual three-dimensional objects and provided binocular, shading, and texture information specifying three-dimensional form, but did not provide informative transformations of linear perspective. In Study 1, 6-month-olds showed changes in preference from pre- to posttest that were related to the identity of the object whose shadow they had seen during habituation; 4-month-olds, however, did not show preference changes related to the habituation object. In Study 2, rhythm information that may have served as a basis for responding in Study 1 was eliminated from the test displays. Six-month-olds again showed changes in preference that were dependent on their habituation experience. It is concluded that, by 6 months of age, infants are able to perceive object structure from the isolated cue of transformations of linear perspective. The findings are discussed with reference to infants’ three-dimensional form perception based on other cues and also with reference to the emergence of certain spatially related moter activities.     

The intergenerational transmission of relationship instability: A focus on emerging adult on-off relationships

This study extends prior research on the intergenerational transmission of relationship instability by examining parents' history of on-off relationships as a predictor of emerging adults' own cycling (i.e., breaking up and renewing with the same romantic partner). Data were collected at a large mid-western university from 702 emerging adults (18–25 years old). Multinomial logistic regression was used to predict the likelihood that participants had cycled in a past or current relationship. Results show that parental cycling increased the likelihood of offspring cycling in a past or current relationship relative to never cycling, and greater uncertainty about the future of the relationship was a mechanism through which such transmission occurred. Findings from this study demonstrate that parental relationship instability can even be consequential for the transient relationships within emerging adulthood, making family history a productive area to explore for practitioners working with cyclical partners and/or emerging adults.     

Examining awareness of privilege among midwestern college students: An analysis of race/ethnicity,gender, and religion

Dominant group members often are not aware of the privileges they benefit from due to their dominant group membership. Yet individuals are members of multiple groups and may simultaneously occupy multiple categories of dominance and marginality, raising the question of how different group memberships work in concert to facilitate or inhibit awareness of multiple forms of privilege. Examining awareness of privilege is important as awareness may be linked to action to dismantle systems of privilege that maintain oppression and inequality. Grounded in intersectional scholarship, in this study we examined how occupying intersecting categories of race/ethnicity, gender, and religion corresponded to an awareness of White, male, and Christian privilege. In a sample of 2321 Midwestern college students, we demonstrated that students from marginalized groups broadly reported greater awareness of all forms of privilege than students from dominant groups, and the difference between marginalized and dominant groups was most pronounced when the specific group category (e.g., gender) aligned with the type of privilege (e.g., male privilege). We also tested interactions among race/ethnicity, gender, and religion, only finding an interaction between race/ethnicity and religion for awareness of White and male privilege. These findings helped to clarify that multiple group memberships tended to contribute to awareness as multiple main effects rather than as multiplicative. Finally, we examined mean differences among the eight intersected groups to explore similarities and differences among groups in awareness of all types of privilege. Taken together, these findings quantitatively demonstrate the ways in which group memberships work together to contribute to awareness of multiple forms of privilege. We discuss study limitations and implications for community psychology research and practice.     

Language preference in the domestic dog (Canis familiaris)

Animal Cognition - Studies have shown that both cotton-top tamarins as well as rats can discriminate between two languages based on rhythmic cues. This is similar to the capabilities of young...