Logics for Epistemic Programs

We construct logical languages which allow one to represent a variety of possible types of changes affecting the information states of agents in a multi-agent setting. We formalize these changes by defining a notion of epistemic program. The languages are two-sorted sets that contain not only sentences but also actions or programs. This is as in dynamic logic, and indeed our languages are not significantly more complicated than dynamic logics. But the semantics is more complicated. In general, the semantics of an epistemic program is what we call aprogram model. This is a Kripke model of ‘actions’,representing the agents' uncertainty about the current action in a similar way that Kripke models of ‘states’ are commonly used in epistemic logic to represent the agents' uncertainty about the current state of the system. Program models induce changes affecting agents' information, which we represent as changes of the state model, called epistemic updates. Formally, an update consists of two operations: the first is called the update map, and it takes every state model to another state model, called the updated model; the second gives, for each input state model, a transition relation between the states of that model and the states of the updated model. Each variety of epistemic actions, such as public announcements or completely private announcements to groups, gives what we call an action signature, and then each family of action signatures gives a logical language. The construction of these languages is the main topic of this paper. We also mention the systems that capture the valid sentences of our logics. But we defer to a separate paper the completeness proof. The basic operation used in the semantics is called the update product. A version of this was introduced in Baltag et al. (1998), and the presentation here improves on the earlier one. The update product is used to obtain from any program model the corresponding epistemic update, thus allowing us to compute changes of information or belief. This point is of interest independently of our logical languages. We illustrate the update product and our logical languages with many examples throughout the paper.     

How does encoding context affect memory in younger and older adults?

How does encoding context affect memory? Participants studied visually presented words viewed concurrently with a rich (intact face) or weak (scrambled face) image as context and subsequently made "Remember", "Know", or "New" judgements to words presented alone. In Experiment 1a, younger, but not older, adults showed higher recollection accuracy to words from rich- than from weak-context encoding trials. The age-related deficit in recollection occurred, in Experiment 1b, even when encoding and retrieval time was doubled in older adults, suggesting that insufficient processing time cannot account for this age-related deficit. In Experiment 1c, dividing attention in young, during encoding, reduced overall memory, though the recollection boost from rich encoding contexts remained, suggesting that reduced attention resources cannot explain this age-related deficit. Experiment 2 showed that an own-age bias, to face images as context, could not explain the age-related differences either. Results suggest that age deficits in recollection stem from a lack of spontaneous binding, or elaboration, of context to target information during encoding.     

Minimising risks and distractions for young drivers and their passengers: An evaluation of a novel driver–passenger training program

The purpose of the present study was to evaluate a pilot program designed to teach communication skills to young drivers and passengers. Sixty-two young males recruited as 31 pairs of friends, all aged between 18 and 21 years and holding a probationary drivers licence, were randomly assigned to a training or no-training condition. A training program was developed based upon elements of existing team training programs. Driver and passenger pairs operated a driving simulator through scenarios designed to measure aspects of safe driving behaviour and hazard response. Communications between driver and passenger were also measured. All participants were administered the Driver Behaviour Questionnaire before and approximately 2 months after simulator testing. Compared to the untrained group the trained participants exhibited a larger following distance, reduced speed significantly when faced with an unexpected hazard on the road, and exhibited more safe communications. Although current passenger restrictions are warranted, the present results reveal an alternative view of adolescent passengers: rather than being a negative influence on drivers, adolescent passengers can potentially be trained to become a positive influence.     

Development of a repeated measures affective change blindness task

Flicker-induced change blindness paradigms have been used to explore attentional biases for a range of concern-related cues. However, previous studies have had limitations related to concerns about carryover effects in repeated measures designs, as well as problems with response modalities. The present article develops a repeated measures paradigm utilising nonverbal responses and explores the implications of these design modifications for the reliability and validity of the paradigm. Affective stimuli were presented to participants, and the results suggest that the modified paradigm is a useful tool for assessing attentional bias. A number of recommendations for the future use of this methodology are made.     

The effect of attending to motor overflow on its voluntary inhibition in young and older adults

Motor overflow refers to involuntary movement or muscle activity coinciding with voluntary movement. We examined whether 16 young adults (18-30 years) and 16 older adults (50-80 years) could voluntarily inhibit overflow. Participants performed a finger pressing task, exerting 50% of their maximal force. Overflow was concurrently recorded in the non-task hand. In the first condition, participants were not made aware of their motor overflow. Then participants, though informed of it, were asked to ignore their overflow. Finally, participants were requested to inhibit overflow with, and then without visual feedback, or vice versa. Overflow was exacerbated when older adults were unaware of it, and was reduced once they were informed. For young adults there was no significant difference between these conditions. Both Age Groups could significantly reduce overflow when so requested, independent of visual feedback. Thus motor overflow can be modulated by higher order cognitive control with directed attention.     

‘Mutual Obligation’ and ‘New Deal’: Illegitimate and Unjustified?

It is now commonplace for governments in Western countries to require the unemployed to work in exchange for their unemployment benefits. In this article I raise some serious doubts about the most promising and philosophically interesting defence of this argument, which relies on the ‘principle of reciprocity’. I argue that it is seriously unclear whether the obligations imposed on welfare claimants by ‘workfare’ schemes are legitimate and justified according to the principle of reciprocity. I do this by reconstructing the arguments for the obligations of the unemployed put forward in both the United Kingdom and Australia.     

Maintaining an open mind to closed individuals: The effect of resource availability and leadership style on the association between openness to experience and organizational commitment

This paper examines whether workplace characteristics, particularly resource availability and transformational leadership, moderate the association between openness to experience and organizational commitment. In Study 1, 205 employees completed a questionnaire that assessed their openness, organizational commitment, and perceived availability of resources at their organization. Openness reduced the extent to which individuals felt obliged to remain loyal to the organization, although this association diminished as resources became more accessible. In Study 2, 312 employees completed a similar questionnaire that also gauged the perceived leadership style of their supervisors. Transformational leadership amplified the positive relationship between openness and organizational commitment. These findings align with the proposition that individuals are more committed in work environments that facilitate the expression of their traits.     

Reviews: Books, Theater, and Painting

JUNG AND THE POSTMODERN: THE INTERPRETATION OF REALITIES. By Christopher Hauke. 304 pp. London & Philadelphia: Routledge, 2000. THE FASHIONING OF ANGELS: PARTNERSHIP AS SPIRITUAL PRACTICE. By Stephen and Robin Larsen. pp. Chrysalis Books, 2000, $19.95. CHILDREN IN THERAPY: USING THE FAMILY AS A RESOURCE. Edited by C. Everett Bailey. 529 pp. New York: W. W. Norton & Company, 2000. $45.00. THE PSYCHOLOGY OF RELIGION AND COPING: THEORY, RESEARCH, PRACTICE. By Kenneth I. Pargament. New York: Guilford Press, 1997. $50.00. SOUL WILDERNESS: A DESERT SPIRITUALITY. By Kerry Walters. 153pp. New York/Mahwah, N.J.: Paulist Press, 2001. $12.95. SOUL MAKING: THE DESERT WAY OF SPIRITUALITY. By Alan Jones. 215 pp. San Francisco: HarperCollins, 1985. $16.00. Theater: Words of Albert Schweitzer and the Music of Bach. Painting: Vermeer and the Delft School     

The Gradual Deterioration of Syntax and Semantics in a Patient with Progressive Aphasia

FM is a progressive aphasic patient whose language comprehension we studied over a 4-year period. We developed a variety of implicit and explicit tasks to chart progressive changes in the representation of linguistic knowledge (in particular, syntax and semantics) and the automatic and controlled processes which operate on that knowledge. The representation of FM's semantic knowledge remained essentially intact over the years, but she became increasingly impaired at combining the meanings of words. She also showed progressive impairments in the processes of syntactic combination. Thus, FM's disease resulted in a progressive inability to engage in those combinatorial processes necessary for the normal comprehension of a spoken utterance. This is not a selective deficit in the traditional sense of the term, since aspects of both syntax and semantics are implicated; but it is selective in the sense that other aspects of language comprehension remain intact.