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161.
To examine the role of perceptual object representations in the control of eye movements and attention, a pair of experiments adapted the object-cuing paradigm of Egly, Driver, and Rafal (1994) to require eye movements. Displays were pairs of adjacent rectangles, each containing two characters. Observers were asked to make a speeded judgment of a target character’s orientation, and a cue was provided prior to target/distractor onset to indicate the target’s likely location. Gaze-contingent presentation of target and distractors was used to demand overt scanning of displays. Eye movements during task performance evinced two forms of object-based effects. First, saccades following fixation on an invalidly cued item were more likely to be made within the cued rectangle than between rectangles. Second, saccades within the cued rectangle were preceded by shorter dwell times than saccades between rectangles. Extrafoveal processing of stimuli within the cued rectangle, however, was not facilitated, suggesting that covert attention was not allocated more densely within the cued than within the uncued object. 相似文献
162.
Two functionally distinct forms of recognition memory have been identified in human and nonhuman species—the ability to recollect qualitative information about previous events, and the ability to differentiate between familiar and novel stimuli. Separate dual-process theories have been developed in the animal and human literatures to account for these findings. However, it is not clear whether these theories describe the same two underlying memory processes. On the basis of animal studies of medial temporal lobe function, familiarity is expected to exhibit disproportionately fast forgetting compared with recollection over short retention intervals. We tested this prediction in healthy human subjects by examining recognition forgetting rates across a range of 8–32 intervening items and found significant forgetting in the accuracy of familiarity-based discriminations and no evidence of forgetting in the accuracy of recollection-based discriminations. In agreement with the results from nonhuman species, the present results indicate that item familiarity decreases more rapidly than recollection over short retention intervals. 相似文献
163.
The ALCOVE model of category learning, despite its considerable success in accounting for human performance across a wide
range of empirical tasks, is limited by its reliance on spatial stimulus representations. Some stimulus domains are better
suited to featural representation, characterizing stimuli in terms of the presence or absence of discrete features, rather
than as points in a multidimensional space. We report on empirical data measuring human categorization performance across
a featural stimulus domain and show that ALCOVE is unable to capture fundamental qualitative aspects of this performance.
In response, a featural version of the ALCOVE model is developed, replacing the spatial stimulus representations that are
usually generated by multidimensional scaling with featural representations generated by additive clustering. We demonstrate
that this featural version of ALCOVE is able to capture human performance where the spatial model failed, explaining the difference
in terms of the contrasting representational assumptions made by the two approaches. Finally, we discuss ways in which the
ALCOVE categorization model might be extended further to use “hybrid” representational structures combining spatial and featural
components. 相似文献
164.
Nersesyan AK 《Science and engineering ethics》2002,8(3):291-293
The author describes problems facing Armenia in reorganization of the structure of science in the post-socialist era with
the aim of utilizing limited state resources more efficiently by reducing the number of separate scientific institutes, concentrating
on essential core subjects required by the nation and encouraging all other projects to compete in the international arena
for grant sponsorship.
An earlier version of this paper was presented at an International Conference on “Conflict of Interest and its Significance
in Science and Medicine” held in Warsaw, Poland on 5–6 April, 2002. 相似文献
165.
Xenotransplantation, or the use of animal cells, tissues and organs for humans, has been promoted as an important solution
to the worldwide shortage of organs. While scientific studies continue to be done to address problems of rejection and the
possibility of animal-to-human virus transfer, socio-ethical and legal questions have also been raised around informed consent,
life-long monitoring, animal welfare and animal rights, and appropriate regulatory practices. Many calls have also been made
to consult publics before policy decisions are made. This paper describes the Canadian public consultation process on xenotransplantation
carried out by the Canadian Public Health Association in an arm’s length process from Health Canada, the ministry overseeing
government health policy and regulation. Focusing on six citizen fora conducted around the country patterned after the citizen
jury deliberative approach, the paper describes the citizen panelists’ recommendations to hold off on proceeding with clinical
trials and the rationales behind this recommendation. The consultation process is discussed in the context of constructive
technology assessment, a framework which argues for broader input into earlier stages of technology innovation, particularly
at the technology design stage.
This study was supported by a grant to the first author from the Social Sciences and Humanities Research Council in Canada. 相似文献
166.
167.
An adult California sea lion (Zalophus californianus) with extensive experience in performing discrimination learning tasks was tested to evaluate her long-term memory for two
previously learned concepts. An associative concept, that of equivalence classification, was retested after a retention interval
of approximately 1 year. The sea lion had originally shown emergent equivalence classification with nonsimilarity-based classes
of stimuli in a simple discrimination repeated-reversal procedure as well as in a matching-to-sample procedure. The 1-year
memory test revealed no decrement in classification performance in either procedure. A relational concept, that of generalized
identity matching, was retested after approximately 10 years. The sea lion had originally received trial-and-error exemplar
training with identity matching-to-sample problems prior to transferring the concept to novel stimulus configurations. In
the 10-year memory test, the sea lion immediately and reliably applied the previously established identity concept to familiar
and novel sets of matching problems. These are the first reports of long-term conceptual memory in a nonprimate species. The
experimental findings are consistent with a variety of observations of sea lions in natural settings, which indicate that
natal sites, feeding areas, and individuals may be remembered over long periods of time. Electronic Supplementary Material is available if you access this article at http://dx.doi.org/10.1007/s10071-002-0153-8. On that page (frame on the left side),
a link takes you directly to the supplementary material.
Electronic Publication 相似文献
168.
Nieuwenhuis S Ridderinkhof KR Talsma D Coles MG Holroyd CB Kok A van der Molen MW 《Cognitive, affective & behavioral neuroscience》2002,2(1):19-36
When participants commit errors or receive feedback signaling that they have made an error, a negative brain potential is elicited. According to Holroyd and Coles’s (in press) neurocomputational model of error processing, this error-related negativity (ERN) is elicited when the brain first detects that the consequences of an action are worse than expected. To study age-related changes in error processing, we obtained performance and ERN measures of younger and high-functioning older adults. Experiment 1 demonstrated reduced ERN amplitudes in older adults in the context of otherwise intact brain potentials. This result could not be attributed to uncertainty about the required response in older adults. Experiment 2 revealed impaired performance and reduced response- and feedback-related ERNs of older adults in a probabilistic learning task. These age changes could be simulated by manipulation of a single parameter of the neurocomputational model, this manipulation corresponding to weakened phasic activity of the mesencephalic dopamine system. 相似文献
169.
Manbir?SodhiEmail author Bryan?Reimer Ignacio?Llamazares 《Behavior research methods》2002,34(4):529-538
With the increasing use of in-vehicle devices in cars, an understanding of the safety implications of secondary tasks has become crucial. It is now possible to study the effects of many in-vehicle devices and tasks on driving by using head-mounted eye-tracking devices (HEDs) to collect eye positions and pupil diameters, which have been considered indicators of attentional focus. The collection of eye-position and pupil-diameter data of automobile drivers under on-road conditions and while completing various secondary tasks is described in this paper. Drivers were asked to drive on a preselected two-lane road for a total distance of 22 miles while gaze data were recorded using a HED. Longer off-road fixation durations were observed in radio-tuning and rearview mirror checking tasks, but not in the odometer checking task. In addition, the standard deviations of fixation displacements during a cognitive task involving the computation of a date for a meeting were shorter than those observed during normal driving. 相似文献
170.
Laura?Barca Cristina?BuraniEmail author Lisa?S.?Arduino 《Behavior research methods》2002,34(3):424-434
The present study describes normative measures for 626 Italian simple nouns. The database (LEXVAR. XLS) is freely available for down-loading on the Web site http://wwwistc.ip.rm.cnr.it/material/ database/. For each of the 626 nouns, values for the following variables are reported: age of acquisition, familiarity, imageability, concreteness, adult written frequency, child written frequency, adult spoken frequency, number of orthographic neighbors, mean bigram frequency, length in syllables, and length in letters. A classification of lexical stress and of the type of word-initial phoneme is also provided. The intercorrelations among the variables, a factor analysis, and the effects of variables and of the extracted factors on word naming are reported. Naming latencies were affected primarily by a factor including word length and neighborhood size and by a word frequency factor. Neither a semantic factor including imageability, concreteness, and age of acquisition nor a factor defined by mean bigram frequency had significant effects on pronunciation times. These results hold for a language with shallow orthography, like Italian, for which lexical nonsemantic properties have been shown to affect reading aloud. These norms are useful in a variety of research areas involving the manipulation and control of stimulus attributes. 相似文献