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.     

Verb frame preferences: Descriptive norms

This paper presents normative data about the frequency with which college students construct sentences with different syntactically defined frames for 127 English verbs. The norms are intended to be of use to experimenters in preparing materials to study sentence comprehension.     

Australia Day or Invasion Day? Perspectives on the Continuing Impact of Colonialism Underlies Public Contestations Around Australia's National Day

The ways in which collective memories are constructed in the present is important in explaining how people choose to commemorate their nation's history. The present research focused on the context of Australia Day, a controversial national holiday that falls on January 26, which is a date that marks the beginning of colonization. We conducted field surveys of community members participating in an Invasion Day protest pushing for Indigenous rights (n = 219) and community members enjoying the public holiday in a public park (n = 174). We found that greater recognition of colonial history explained protesters' (vs. nonprotesters') greater support for changing the date of Australia Day. Further, protesters' lower levels of perceived continuity and higher levels of desired continuity of First Australian culture was linked to greater support for changing the date of Australia Day compared to the nonprotesters. These findings suggest that creating consensus over contested collective memories of a nation's history requires greater recognition of the ongoing impact of past atrocities.     

A personal experience of supervision

TTte author's personal experience and perspective as a feminist counsellor and supervisee is explored. Some key boundary issues are identified which have brought about some important learning for her. These examples illustrate the crucial importance of an awareness of gender issues within both the counselling and the supervisory relationship.     

Two-dimensional reward evaluation in mice

Animal Cognition - When choosing among multi-attribute options, integrating the full information may be computationally costly and time-consuming. So-called non-compensatory decision rules only...     

Narrative access and production in preschoolers' false belief reasoning

False belief tests seem to show the apparent acquisition at around age 4 of an ability to understand the representational status of mind. In this article, preschoolers' performance on a false belief task was manipulated in terms of their grasp of its narrative base. Five experiments are reported in which 3-year-olds were helped to become familiar with the events that comprise the false belief procedure by going through a picture book version of the task, before being asked to judge the protagonist's mental state. In Experiment 1, children who had failed a traditional task succeeded if they narrated the book version back to the experimenter, particularly if they were fluent in their story recall. Experiment 2 showed that this success occurred either if the child recited the story or if she or he was taken through each page twice in succession. Experiment 3 combined the most effective procedures with a younger group of children (mean age 3;3) and revealed 95% success as long as they could recall the prerequisite events. Experiments 4 and 5 probed possible limiting conditions for success by inserting an extra episode in the story and changing the format of the test question. The results suggest that the structure of 3-year-olds' event memories is central to their poor performance in the traditional false belief task—a clear grasp of the false belief “narrative” is necessary for successful performance. When they are given the opportunity to link discrete events into a coherent narrative, they have no problem demonstrating an understanding of others' minds—being able to recount the narrative is sufficient for successful performance.     

Intonation does aid serial recall after all

Psychonomic Bulletin & Review - A sequence of spoken digits is easier to recall if the digits are grouped into smaller chunks (e.g., through the insertion of pauses). It has been claimed that...