The bisection point across variants of the task

Bisection tasks are used in research on normal space and time perception and to assess the perceptual distortions accompanying neurological disorders. Several variants of the bisection task are used, which often yield inconsistent results, prompting the question of which variant is most dependable and which results are to be trusted. We addressed this question using theoretical and experimental approaches. Theoretical performance in bisection tasks is derived from a general model of psychophysical performance that includes sensory components and decisional processes. The model predicts how performance should differ across variants of the task, even when the sensory component is fixed. To test these predictions, data were collected in a within-subjects study with several variants of a spatial bisection task, including a two-response variant in which observers indicated whether a line was transected to the right or left of the midpoint, a three-response variant (which included the additional option to respond “midpoint”), and a paired-comparison variant of the three-response format. The data supported the model predictions, revealing that estimated bisection points were least dependable with the two-response variant, because this format confounds perceptual and decisional influences. Only the three-response paired-comparison format can separate out these influences. Implications for research in basic and clinical fields are discussed.     

Quantity discrimination by kittens of the domestic cat (Felis silvestris catus)

Animal Cognition - Quantitative abilities are well described in many species and in diverse life situations, including in the adult domestic cat. However, such abilities have been much less studied...     

Tolerant macaque species are less impulsive and reactive

Animal Cognition - Inhibitory control, the inhibition of impulsive behaviours, is believed to be key in navigating a complex social environment. Species characterised by higher social tolerance,...     

‘Of the group’ and ‘for the group’: How followership is shaped by leaders' prototypicality and group identification

Previous research has focused on the importance of leaders being seen to be of the group (i.e. to be prototypical of a group) but less on the impact of leaders' own degree of identification with the group. Also, little is known about the combined impact of leader prototypicality and leader identification on followers' responses. This paper reports two studies that address these lacunae. Study 1 shows experimentally that perceived leader identification and prototypicality interact to determine followers' personal identification with leaders and their perceptions of leader charisma. Findings indicate that high identification can compensate for low prototypicality such that high‐identified leaders are able to inspire followership when leaders are low prototypical. Study 2 replicates these findings in the field by examining followers' responses to workgroup leaders. In addition, results demonstrate that the aforementioned responses are more pronounced for highly identified followers. The present research extends social identity theorizing by demonstrating that leaders' inability to inspire followership derives as much from their failure to project a sense of ‘we’ and ‘us’ as part of their self‐concept as from a failure to exemplify group‐typical attributes. Copyright © 2015 John Wiley & Sons, Ltd.     

Rhetorical Strategies for Scientific Authority: A Boundary-Work Analysis of ‘Climategate’

The term ‘Climategate’ refers to the episode in November 2009 when emails between climate scientists were stolen and published online. The content of this private correspondence prompted criticism from diverse commentators who cast doubts on the methods, claims, and members of the climate science community. In response, individual scientists and scientific institutions published statements responding to the allegations of scientific fraud. Gieryn's concept of ‘boundary-work’ can be used to analyse the rhetoric of scientists in situations where their legitimacy is disputed. More specifically, boundary-work can be used to analyse the responses of scientists in terms of: how they represent the attributes of science, what types of boundary-work they undertake (e.g. expulsion, expansion, and protection), and the professional interests that come into play. A boundary-work analysis of the commentaries published in the aftermath of Climategate reveals that scientists characterised climate science as consensual, asocial, and open. Scientists depicted climate science as consensual with the purpose of expelling dissenters and protecting areas of climate science from criticism. Scientists also described knowledge about climate as being ideally produced apart from society so that they could preserve their autonomy and exclude individuals who are accused of being ‘politically biased’. Scientists characterised climate science as necessarily open as the means to justify both existing and additional public funding for science and to avoid external corrective interventions against scientific opacity. Scientists and their critics alike interpreted the stolen emails as embarrassing deviations from the alleged social demands of a consensual, objective, and accessible science.     

Pavlovian eyeblink conditioning in combat veterans with and without post-traumatic stress disorder

Several recent studies have investigated relationships between post-traumatic stress disorder (PTSD) and learning and memory problems. These reports have found in general that not only does PTSD affect trauma-related memories, but when patients with PTSD are compared with similar trauma patients without PTSD, general memory impairments have been found. The present paper reports a study in which associative learning, using Pavlovian eyeblink conditioning, was investigated in combat veterans with and without chronic PTSD, using interstimulus intervals of 500 and 1000 msec in two separate experiments. Although several recent reports suggest that larger-magnitude autonomic conditioned responses occur in patients with PTSD during Pavlovian conditoning, the present study found evidence of impaired Pavlovian eyeblink conditioning in combat veterans with and without PTSD, compared to non-combat veterans. Although these data suggest that combat leads to an impaired associative learning process regardless of whether PTSD is apparent, a group of community-dwelling combat veterans not under medical treatment showed normal conditioning, suggesting that variables other than prior combat must also be involved.     

Targets of the memorized position and visual contexts]

The goal of this study was to determine whether a sensorimotor or cognitive encoding is used to encode a target position and save it into iconic memory. The methodology consisted of disrupting a manual aiming movement to a memorized visual target by displacing the visual field containing the target. The nature of the encoding was inferred from the nature and the size of the errors relative to a control. The target was presented either centrally or in the right periphery. Participants moved their hand from the left to the right of fixation. Black and white vertical stripes covered the whole visual field. The visual field was either stationary throughout the trial or was displaced to the right or left at the extinction of the target or at the start of the hand movement. In the latter case, the displacement of the visual field obviously could only be taken into account by the participant during the gesture. In this condition, our hypothesis was that the aiming error would follow the direction of visual field displacement. Results showed three major effects: (1) Vision of the hand during the gesture improved the final accuracy; (2) visual field displacement produced an underestimation of the target distance only when the hand was not visible during the gesture and was always in the same direction displacement; and (3) the effect of the stationary structured visual field on aiming precision when the hand was not visible depended on the distance to the target. These results suggest that a stationary structured visual field is used to support the memory of the target position. The structured visual field is more critical when the hand is not visible and when the target appears in peripheral rather than central vision. This suggests that aiming depends on memory of the relative peripheral position of the target (allocentric reference). However, in the present task, cognitive encoding does not maintain the "position" of the target in memory without reference to the environment. The systematic effect of the visual field displacement on the manual aiming suggests that the role of environmental reference frames in memory for position is not well understood. Some studies, in particular those of Giesbrecht and Dixon (1999) and Glover and Dixon (2001), suggested differing roles of the environment in the retention of the target position and the control of aiming movements toward the target. The present observations contribute to understanding the mechanism involved in locating and grasping objects with the hand.