Value-driven attentional and oculomotor capture during goal-directed, unconstrained viewing

Covert shifts of attention precede and direct overt eye movements to stimuli that are task relevant or physically salient. A growing body of evidence suggests that the learned value of perceptual stimuli strongly influences their attentional priority. For example, previously rewarded but otherwise irrelevant and inconspicuous stimuli capture covert attention involuntarily. It is unknown, however, whether stimuli also draw eye movements involuntarily as a consequence of their reward history. Here, we show that previously rewarded but currently task-irrelevant stimuli capture both attention and the eyes. Value-driven oculomotor capture was observed during unconstrained viewing, when neither eye movements nor fixations were required, and was strongly related to individual differences in visual working memory capacity. The appearance of a reward-associated stimulus came to evoke pupil dilation over the course of training, which provides physiological evidence that the stimuli that elicit value-driven capture come to serve as reward-predictive cues. These findings reveal a close coupling of value-driven attentional capture and eye movements that has broad implications for theories of attention and reward learning.     

Multiple-object tracking is based on scene, not retinal, coordinates

This study tested whether multiple-object tracking-the ability to visually index objects on the basis of their spatiotemporal history-is scene based or image based. Initial experiments showed equivalent tracking accuracy for objects in 2-D and 3-D motion. Subsequent experiments manipulated the speeds of objects independent of the speed of the scene as a whole. Results showed that tracking accuracy was influenced by object speed but not by scene speed. This held true whether the scene underwent translation, zoom, rotation, or even combinations of all 3 motions. A final series of experiments interfered with observers' ability to see a coherent scene by moving objects at different speeds from one another and by distorting the perception of 3-D space. These reductions in scene coherence led to reduced tracking accuracy, confirming that tracking is accomplished using a scene-based, or allocentric, frame of reference.     

Teaching research ethics: Can web-based instruction satisfy appropriate pedagogical objectives?

Ethical tasks faced by researchers in science and engineering as they engage in research include recognition of moral problems in their practice, finding solutions to those moral problems, judging moral actions and engaging in preventive ethics. Given these issues, appropriate pedagogical objectives for research ethics education include (1) teaching researchers to recognize moral issues in their research, (2) teaching researchers to solve practical moral problems in their research from the perspective of the moral agent, (3) teaching researchers how to make moral judgments about actions, and (4) learning to engage in preventive ethics. If web-based research ethics education is intended to be adequate and sufficient for research ethics education, then it must meet those objectives. However there are reasons to be skeptical that it can.     

Three challenges (and three replies) to the ethics of belief

In this paper I look at three challenges to the very possibility of an ethics of belief and then show how they can be met. The first challenge, from Thomas Kelly, says that epistemic rationality is not (merely) a form of instrumental rationality. If this claim is true, then it will be difficult to develop an ethics of belief that does not run afoul of naturalism. The second challenge is the Non-Voluntarism Argument, which holds that because we cannot believe at will and because ought implies can, there can be no ethics of belief. The third challenge comes from Richard Feldman, who claims that there is no such thing as ought all-things-considered. He says, for example, that moral oughts can be weighed against other moral oughts and that epistemic oughts can be compared to each other, but that there is no way to weigh moral oughts against epistemic oughts. If this is true, then norms about what one ought to believe are not nearly as important as one might have hoped or as philosophers have traditionally thought. In answering these three challenges, I try to show how and why the project of developing epistemic norms might be a promising avenue of research, despite claims to the contrary.     

Sex differences in the emergence of leadership during competitions within and between groups

This experiment investigated potential gender biases in the emergence of leadership in groups. Teams played a public-goods game under conditions of intra- or intergroup competition. We predicted and found a strong preference for female leaders during intragroup competition and male leaders during intergroup competition. Furthermore, during intragroup competition, a female leader was more instrumental than a male leader in raising group investments, but this pattern was reversed during intergroup competition. These findings suggest that particular group threats elicit specific gender-biased leader prototypes. We speculate about the evolutionary and cultural origins of these sex differences in the emergence of leadership.     

Cohesion as a constraint on object persistence in infancy

A critical challenge for visual perception is to represent objects as the same persisting individuals over time and motion. Across several areas of cognitive science, researchers have identified cohesion as among the most important theoretical principles of object persistence: An object must maintain a single bounded contour over time. Drawing inspiration from recent work in adult visual cognition, the present study tested the power of cohesion as a constraint as it operates early in development. In particular, we tested whether the most minimal cohesion violation - a single object splitting into two - would destroy infants' ability to represent a quantity of objects over occlusion. In a forced-choice crawling paradigm, 10- and 12-month-old infants witnessed crackers being sequentially placed into containers, and typically crawled toward the container with the greater cracker quantity. When one of the crackers was visibly split in half, however, infants failed to represent the relative quantities, despite controls for the overall quantities and the motions involved. This result helps to characterize the fidelity and specificity of cohesion as a fundamental principle of object persistence, suggesting that even the simplest possible cohesion violation can dramatically impair infants' object representations and influence their overt behavior.     

Essential independence and likelihood-based ability estimation for polytomous items

A definition ofessential independence is proposed for sequences of polytomous items. For items satisfying the reasonable assumption that the expected amount of credit awarded increases with examinee ability, we develop a theory ofessential unidimensionality which closely parallels that of Stout. Essentially unidimensional item sequences can be shown to have a unique (up to change-of-scale) dominant underlying trait, which can be consistently estimated by a monotone transformation of the sum of the item scores. In more general polytomous-response latent trait models (with or without ordered responses), anM-estimator based upon maximum likelihood may be shown to be consistent for under essentially unidimensional violations of local independence and a variety of monotonicity/identifiability conditions. A rigorous proof of this fact is given, and the standard error of the estimator is explored. These results suggest that ability estimation methods that rely on the summation form of the log likelihood under local independence should generally be robust under essential independence, but standard errors may vary greatly from what is usually expected, depending on the degree of departure from local independence. An index of departure from local independence is also proposed.This work was supported in part by Office of Naval Research Grant N00014-87-K-0277 and National Science Foundation Grant NSF-DMS-88-02556. The author is grateful to William F. Stout for many helpful comments, and to an anonymous reviewer for raising the questions addressed in section 2. A preliminary version of section 6 appeared in the author's Ph.D. thesis.     

Aging Affects the Ability to Process the Optic Flow Stimulations: A Functional Near-Infrared Spectrometry Study

Abstract

Optic flow (OF) has been utilized to investigate the sensory integration of visual stimuli during postural control. It is little known how the OF speed affects the aging brain during the sensory integration process of postural control. This study was to examine the effect of OF speeds on the brain activation using functional near-infrared spectroscopy (fNIRS) and postural sway between younger and older adults. Eleven healthy younger adults (5M/6F, age 22?±?1-year-old) and ten healthy older adults (4M/6F, age 71?±?5-year-old) participated in this study. A virtual reality headset was used to provide the OF stimulus at different speeds. A forceplate was used to record the center-of-pressure to compute the amplitude of postural sway (peak-to-peak). Compared with younger adults, older adults showed significantly increased activation in the OF speed of 10?m/s and decreased activation in the OF speed of 20?m/s in the left dorsolateral prefrontal cortex. Older adults also showed decreased activation in the left temporoparietal region (VEST) in the OF speed of 20?m/s. A significant difference in peak-to-peak was found between groups. Our results indicated that age might be associated with the ability to process fast OF stimulation.