医学哲学:一个不应忽视的课题

本期<医学与哲学>,全文刊载了中国自然辩证法研究会医学哲学专业委员会制定的<医学哲学研究纲要>,这是一个有深远意义的文件.     

When auditory presentations should and should not be a component of multimedia instruction

Based on cognitive load theory, two experiments investigated the conditions under which audiovisual‐based instruction may be an effective or an ineffective instructional technique. Results from Experiment 1 indicated that visual with audio presentations were superior to equivalent visual‐only presentations. In this experiment, neither the auditory nor the visual material could be understood in isolation. Both sources of information were interrelated and were essential to render the material intelligible. In contrast, Experiment 2 demonstrated that a non‐essential explanatory text, presented aurally with similar written text contained in a diagram, hindered learning. This result was obtained because when compared to a diagram only format, the aural material was unnecessary and therefore created a redundancy effect. Differences between groups were stronger when information was high in complexity. It was concluded that the effectiveness of multimedia instruction depends very much on how and when auditory information is used. Copyright © 2003 John Wiley & Sons, Ltd.     

2.5-month-old infants' reasoning about when objects should and should not be occluded.

The present research examined 2.5-month-old infants' reasoning about occlusion events. Three experiments investigated infants' ability to predict whether an object should remain continuously hidden or become temporarily visible when passing behind an occluder with an opening in its midsection. In Experiment 1, the infants were habituated to a short toy mouse that moved back and forth behind a screen. Next, the infants saw two test events that were identical to the habituation event except that a portion of the screen's midsection was removed to create a large window. In one event (high-window event), the window extended from the screen's upper edge; the mouse was shorter than the bottom of the window and thus did not become visible when passing behind the screen. In the other event (low-window event), the window extended from the screen's lower edge; although the mouse was shorter than the top of the window and hence should have become fully visible when passing behind the screen, it never appeared in the window. The infants tended to look equally at the high- and low-window events, suggesting that they were not surprised when the mouse failed to appear in the low window. However, positive results were obtained in Experiment 2 when the low-window event was modified: a portion of the screen above the window was removed so that the left and right sections of the screen were no longer connected (two-screens event). The infants looked reliably longer at the two-screens than at the high-window event. Together, the results of Experiments 1 and 2 suggested that, at 2.5 months of age, infants possess only very limited expectations about when objects should and should not be occluded. Specifically, infants expect objects (1) to become visible when passing between occluders and (2) to remain hidden when passing behind occluders, irrespective of whether these have openings extending from their upper or lower edges. Experiment 3 provided support for this interpretation. The implications of these findings for models of the origins and development of infants' knowledge about occlusion events are discussed.     

When Seeing should not be Believing: Photographs,Credit Cards and Fraud

Identity cards often include a photograph of the bearer in an attempt to prevent fraudulent use or personation. In the U.K. some credit card companies have recently introduced photo-credit cards and the government is currently considering the introduction of a new driving licence including the bearer's photograph. However, the widely held belief that the inclusion of photographs will reduce or prevent fraudulent use has never been tested. This paper describes a field study designed to examine the utility of photo-credit cards by assessing the accuracy with which supermarket cashiers could identify whether the photographs on credit cards depicted the person tendering them. The results demonstrate that the task of matching the photograph to the shopper is much more difficult than might be expected, and that even under optimized conditions, performance is poor. It is concluded that the introduction of photographs on credit cards would have little effect on the detection of fraud at the point of sale. © 1997 by John Wiley & Sons, Ltd.     

The autonomy of adult women should be paramount, not the exam

The respect shown by clinic personnel for the adult status of their patients, and the right of people with mental retardation to good routine gynecologic care are not at issue. What is at issue is the right of a mentally retarded woman to refuse the intrusion of a pelvic examination. To accept an accommodated decisional capacity to say yes or indicate assent but to deny the reverse might be in the patients' medical best interest, but it is neither consistent nor respectful of their autonomy.     

Contextual cost: When a visual-search target is not where it should be

Visual search is often facilitated when the search display occasionally repeats, revealing a contextual-cueing effect. According to the associative-learning account, contextual cueing arises from associating the display configuration with the target location. However, recent findings emphasizing the importance of local context near the target have given rise to the possibility that low-level repetition priming may account for the contextual-cueing effect. This study distinguishes associative learning from local repetition priming by testing whether search is directed toward a target's expected location, even when the target is relocated. After participants searched for a T among Ls in displays that repeated 24 times, they completed a transfer session where the target was relocated locally to a previously blank location (Experiment 1) or to an adjacent distractor location (Experiment 2). Results revealed that contextual cueing decreased as the target appeared farther away from its expected location, ultimately resulting in a contextual cost when the target swapped locations with a local distractor. We conclude that target predictability is a key factor in contextual cueing.     

Detecting true and false opinions: The Devil's Advocate approach as a lie detection aid

We examined the efficacy of a new approach to detect truths and lies in expressing opinions: the Devil's Advocate approach. Interviewees are first asked an opinion eliciting question that asks participants to argue in favour of their personal view. This is followed by a Devil's Advocate question that asks participants to argue against their personal view. People normally think more about reasons that support rather than oppose their opinion. Therefore we expected truth tellers to provide more information and shorter latency times in their responses to the opinion eliciting question than to the Devil's Advocate question. Liars are expected to reveal the opposite pattern as the Devil's Advocate question is more compatible with their beliefs than is the opinion eliciting question. In Experiment 1, we interviewed seventeen truth tellers and liars via the Devil's Advocate approach and measured the difference in number of words and latency times to the two questions. Our hypotheses were supported. In Experiment 2, 25 observers were shown these interviews, and made qualitative judgements about the statements. Truth tellers' opinion eliciting answers were seen as more immediate and plausible and revealed more emotional involvement than their Devil's Advocate answers. No clear differences emerged in liars' answers to the two types of question. We conclude that the Devil's Advocate approach is a promising lie detection approach that deserves attention in future research.     

The Mirror and I: When private opinions are in conflict with public norms

In two studies it is demonstrated that two self-saliency manipulations, often used interchangeably, can have profoundly different consequences. Whereas self-activation increased stereotyping in highly prejudiced participants, a mirror decreased stereotyping. Results show that this difference can be ascribed to the activation of specific self-aspects. Whereas a mirror increased both private and public self-awareness (and, hence, awareness of the social norm that stereotyping is bad), self-activation increased private self-awareness exclusively (and, hence, awareness of privately held negative stereotypes). The implications of these findings for the relation between self-awareness and conformity to social norms are discussed.     

Abiding by the law when it does not exist: The case of the helmet bicycle law

To improve the safety of bicycle users, some countries have enacted, or considered enacting, mandatory helmet legislation. Of course, the enactment of such legislation in a country assumes that its citizens will be well-informed of it, and consequently, will use the helmet more frequently than before. However, in the survey described in this paper we found that many people are not aware of the legislation in force in their own country, or, even if they know, they may not necessarily behave as dictated by the law. Thus, the effects of mandatory helmet legislation may be somewhat different than desired or expected. Therefore, the goal of this paper is to ascertain the role of cyclists’ knowledge of the law in their country as a mediator between the law and the actual use of the helmet. Respondents from seventeen countries participated in an international survey about cyclists' habits, and answered questions about helmet legislation, and frequency of helmet use. The results indicate that the main effect of mandatory helmet legislation on the frequency of use of the helmet is mediated by the perception that such a law exists in their country—even when in fact sometimes it does not exist.     

Option weights should be determined empirically and not by experts when assessing knowledge with multiple‐choice items

Multiple‐choice tests are frequently used in personnel selection contexts to measure knowledge and abilities. Option weighting is an alternative multiple‐choice scoring procedure that awards partial credit for incomplete knowledge reflected in applicants’ distractor choices. We investigated whether option weights should be based on expert judgment or on empirical data when trying to outperform conventional number‐right scoring in terms of reliability and validity. To obtain generalizable results, we used repeated random sub‐sampling validation and found that empirical option weighting, but not expert option weighting, increased the reliability of a knowledge test. Neither option weighting procedure improved test validity. We recommend to improve the reliability of existing ability and knowledge tests used for personnel selection by computing and publishing empirical option weights.     

To be and not to be: Dialectical tense logic

The paper concerns time, change and contradiction, and is in three parts. The first is an analysis of the problem of the instant of change. It is argued that some changes are such that at the instant of change the system is in both the prior and the posterior state. In particular there are some changes from p being true to p being true where a contradiction is realized. The second part of the paper specifies a formal logic which accommodates this possibility. It is a tense logic based on an underlying paraconsistent prepositional logic, the logic of paradox. (See the author's article of the same name Journal of Philosophical Logic 8 (1979).) Soundness and completeness are established, the latter by the canonical model construction, and extensions of the basic system briefly considered. The final part of the paper discusses Leibniz's principle of continuity: Whatever holds up to the limit holds at the limit. It argues that in the context of physical changes this is a very plausible principle. When it is built into the logic of the previous part, it allows a rigorous proof that change entails contradictions. Finally the relation of this to remarks on dialectics by Hegel and Engels is briefly discussed.