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J David Smith

Publications and source records attributed to J David Smith.

At least 19 recordsLinked to original sources
PubMed2006

Dissociating uncertainty responses and reinforcement signals in the comparative study of uncertainty monitoring.

Although researchers are exploring animals' capacity for monitoring their states of uncertainty, the use of some paradigms allows the criticism that animals map avoidance responses to error-causing stimuli not because of uncertainty monitored but because of feedback signals and stimulus aversion. The authors addressed this criticism with an uncertainty-monitoring task in which participants completed blocks of trials with feedback deferred so that they could not associate reinforcement signals to particular stimuli or stimulus-response pairs. Humans and 1 of 2 monkeys were able to make cognitive, decisional uncertainty responses that were independent of feedback or reinforcement history within a task. This finding unifies the comparative literature on uncertainty monitoring. The dissociation of performance from reinforcement has theoretical implications, and the deferred-feedback technique has many applications.

Adolescent↗
PubMed2006

Rhesus macaques (Macaca mulatta) monitor uncertainty during numerosity judgments.

Two rhesus macaques (Macaca mulatta) judged arrays of dots on a computer screen as having more or fewer dots than a center value that was never presented in trials. After learning a center value, monkeys were given an uncertainty response that let them decline to make the numerosity judgment on that trial. Across center values (3-7), errors occurred most often for sets adjacent in numerosity to the center value. The monkeys also used the uncertainty response most frequently on these difficult trials. A 2nd experiment showed that monkeys' responses reflected numerical magnitude and not the surface-area illumination of the displays. This research shows that monkeys' uncertainty-monitoring capacity extends to the domain of numerical cognition. It also shows monkeys' use of the purest uncertainty response possible, uncontaminated by any secondary motivator.

Animals↗
PubMed2006

Rhesus monkeys (Macaca mulatta) immediately generalize the uncertain response.

Rhesus monkeys (Macaca mulatta) have learned, like humans, to use an uncertain response adaptively under test conditions that create uncertainty, suggesting a metacognitive process by which human and nonhuman primates may monitor their confidence and alter their behavior accordingly. In this study, 4 rhesus monkeys generalized their use of the uncertain response, without additional training, to 2 familiar tasks (2-choice discrimination learning and mirror-image matching to sample) that predictably and demonstrably produce uncertainty. The monkeys were significantly less likely to use the uncertain response on trials in which the answer might be known. These results indicate that monkeys, like humans, know when they do not know and that they can learn to use a symbol as a generalized means for indicating their uncertainty.

Adaptation, Psychological↗
PubMed2006

Stages of abstraction and exemplar memorization in pigeon category learning.

It has been proposed that human category learning consists of an early abstraction-based stage followed by a later exemplar-memorization stage. To investigate whether similar processing stages extend to category learning in a nonverbal species, we applied a prototype-exception paradigm to investigating pigeon category learning. Five birds and 8 humans learned six-dimensional perceptual categories constructed to include prototypes, typical items, and exceptions. We evaluated the birds' and humans' categorization strategies at different points during learning. Early on in both species, prototype performance improved rapidly as exception performance remained below chance, indicating an initial mastery of the categories' general structure. Later on, exception performance improved selectively and dramatically, indicating exception-item resolution and exemplar memorization. Abstraction- and exemplar-based formal models reinforced these interpretations. The results suggest a psychological transition in pigeon category learning from abstraction- to exemplar-based processing similar to that found in humans.

Animals↗
PubMed2006

Inclusion of people with mental retardation and other developmental disabilities in communities of faith.

Our focus in this paper is on efforts to include persons with developmental disabilities in faith communities. We provide a review of the relevant literature on religious participation and faith communities for persons with disabilities and blend the limited data available on these topics with the perspectives of individuals whose efforts focus on these concerns. Topics explored are the implications of being part of the faith community in terms of its impact on quality of life, the barriers to inclusion in such communities, strategies for overcoming these barriers, and special considerations for adults with mental retardation or other developmental disabilities. Discussion of the implications for enhancing inclusion in faith communities is provided.

Adolescent↗
PubMed2005

Alkali metal complexes of sterically hindered mono- and di-carbanions containing Si-O bonds.

The oxygen-bridged, silicon-substituted alkane {(Me3Si)2CH(SiMe2)}2O (1) may be prepared by the reaction of {(Me3Si)2CH}Li with ClSiMe2OSiMe2Cl in refluxing THF. Similarly, the alkane {(Me3Si)(Me2MeOSi)CH(SiMe2CH2)}2 (2) is readily accessible from the reaction between {(Me3Si)(Me2MeOSi)CH}Li and ClSiMe2CH2CH2SiMe2Cl under the same conditions. Compound 1 reacts with two equivalents of MeK to give the polymeric complex [[{(Me3Si)2C(SiMe2)}2O]K2(OEt2)]infinity [5(OEt2)] after recrystallisation. Treatment of 2 with two equivalents of either MeLi or MeK gives the corresponding complexes [{(Me3Si)(Me2MeOSi)C(SiMe2CH2)}2Li][Li(DME)3] [7(DME)3] and [{(Me3Si)(Me2MeOSi)C(SiMe2CH2)}2K2]n (8), respectively, after recrystallisation. Treatment of the alkane (Me3Si)2(Me2MeOSi)CH with one equivalent of MeK gives the polymeric complex [{(Me3Si)2(Me2MeOSi)C}K]infinity (3). These compounds have been identified by 1H and 13C{1H} NMR spectroscopy and elemental analyses and compounds 5(OEt2), 7(DME)3 and 3 have been further characterised by X-ray crystallography. Compound 7(DME)3 crystallises as a solvent-separated ion pair, whereas 5(OEt2) and 3 adopt polymeric structures in the solid state.

Journal Article↗
PubMed2005

Visual search and the collapse of categorization.

Categorization researchers typically present single objects to be categorized. But real-world categorization often involves object recognition within complex scenes. It is unknown how the processes of categorization stand up to visual complexity or why they fail facing it. The authors filled this research gap by blending the categorization and visual-search paradigms into a visual-search and categorization task in which participants searched for members of target categories in complex displays. Participants have enormous difficulty in this task. Despite intensive and ongoing category training, they detect targets at near-chance levels unless displays are extremely simple or target categories extremely focused. These results, discussed from the perspectives of categorization and visual search, might illuminate societally important instances of visual search (e.g., diagnostic medical screening).

Adult↗
PubMed2005

Specific-token effects in screening tasks: possible implications for aviation security.

Screeners at airport security checkpoints perform an important categorization task in which they search for threat items in complex x-ray images. But little is known about how the processes of categorization stand up to visual complexity. The authors filled this research gap with screening tasks in which participants searched for members of target categories in visual displays. The authors found that when targets were sampled with replacement and repetition, participant screeners relied on recognizing familiar targets and had great difficulty using category-general knowledge. The authors observed a "heartbeat" in detection performance--it improved while test images repeated but dropped sharply when unfamiliar targets from the same categories appeared. This reliance on familiarity illuminates the processes of categorization under conditions of visual complexity and suggests limits on those processes. This reliance also has implications for the training and evaluation of screeners in the field.

Aviation↗
PubMed2005

Wanted: a new psychology of exemplars.

Present-day exemplar theory faces difficult challenges, and important questions have arisen about the kinds of exemplar effects and processes that are empirically supported, and about the kind of exemplar theory that could still be constructive. One question concerns whether exemplar generalization in memory and categorization is broad and collective--extending to many related exemplars stored in memory--or whether it is focused and singular--extending only to highly similar (nearly identical) exemplars. The present article considers this continuum from broad to narrow generalization. I demonstrate that in prominent memory and category tasks--tasks in which exemplar theory predicts broad generalization--generalization is in psychological reality very tightly focused. These demonstrations could ground a new, productive exemplar theory that is true to psychological process as humans conduct themselves in memory and category tasks. This new psychology may actually reprise the traditional exemplar theory that predated our sophisticated, mathematical exemplar models.

Association↗
PubMed2005

Confidence judgments by humans and rhesus monkeys.

Researchers have begun to evaluate animals' metacognitive capacities. Continuing this evaluation, the present authors asked whether monkeys could use the analog of a confidence-rating scale to judge retrospectively their accuracy in a psychophysical discrimination. Monkeys and human participants classified stimuli as dense or sparse without feedback. Then, they made a secondary confidence judgment by choosing responses that risked different levels of timeout but could earn different levels of reward. Human participants were instructed to use these responses to express levels of confidence. They used 2- and 3-level confidence-rating scales appropriately. Monkeys used the 2-level scale appropriately--especially one who performed almost identically to humans. Neither monkey used the 3-level scale as the humans did. These studies place humans and animals for the first time in the identical risk-taking situation that collects declarative confidence judgments from humans. They demonstrate the first retrospective reports of uncertainty by non-human primates while also suggesting their limits in this area.

Animals↗
PubMed2004

Category learning in rhesus monkeys: a study of the Shepard, Hovland, and Jenkins (1961) tasks.

In influential research, R. N. Shepard, C. I. Hovland, and H. M. Jenkins (1961) surveyed humans' categorization abilities using tasks based in rules, exclusive-or (XOR) relations, and exemplar memorization. Humans' performance was poorly predicted by cue-conditioning or stimulus-generalization theories, causing Shepard et al. to describe it in terms of hypothesis selection and rule application that were possibly supported by verbal mediation. The authors of the current article surveyed monkeys' categorization abilities similarly. Monkeys, like humans, found category tasks with a single relevant dimension the easiest and perceptually chaotic tasks requiring exemplar memorization the most difficult. Monkeys, unlike humans, found tasks based in XOR relations very difficult. The authors discuss the character and basis of the species difference in categorization and consider whether monkeys are the generalization-based cognitive system that humans are not.

Animals↗
PubMed2003

The structure of tri(cyclohexyl)tin chloride between 108 and 298 K: a compound in which molecular dimensions vary with temperature.

Care is necessary when relating physical data obtained at one temperature on compounds showing significant intermolecular interactions to X-ray data obtained at other temperatures. This is revealed by the determination of the structure of tri(cyclohexyl)tin chloride at nine different temperatures between 108 and 298 K. In the crystal, the molecules pack in chains parallel to the c axis with the Sn and Cl atoms close to the plane, with y = 0.25. At low temperature, successive molecules in the chain are related by the glide plane in space group P2(1)/c, and there is significant intermolecular interaction. As the temperature is raised, the Cy(3)SnCl.Sn interactions weaken and the intramolecular Sn-Cl bonds strengthen. At about 248 K, there is an order-disorder transition to space group P2(1)/m with the c axis halved, and at room temperature the structure is best described as comprising discrete molecules, as previously reported. Thus, some of the molecular dimensions, in particular the Sn-Cl bond lengths, are not constant but are functions of temperature.

Journal Article↗
PubMed2003

The comparative psychology of uncertainty monitoring and metacognition.

Researchers have begun to explore animals' capacities for uncertainty monitoring and metacognition. This exploration could extend the study of animal self-awareness and establish the relationship of self-awareness to other-awareness. It could sharpen descriptions of metacognition in the human literature and suggest the earliest roots of metacognition in human development. We summarize research on uncertainty monitoring by humans, monkeys, and a dolphin within perceptual and metamemory tasks. We extend phylogenetically the search for metacognitive capacities by considering studies that have tested less cognitively sophisticated species. By using the same uncertainty-monitoring paradigms across species, it should be possible to map the phylogenetic distribution of metacognition and illuminate the emergence of mind. We provide a unifying formal description of animals performances and examine the optimality of their decisional strategies. Finally, we interpret animals' and humans' nearly identical performances psychologically. Low-level, stimulus-based accounts cannot explain the phenomena. The results suggest granting animals a higher-level decision-making process that involves criterion setting using controlled cognitive processes. This conclusion raises the difficult question of animal consciousness. The results show that animals have functional features of or parallels to human conscious cognition. Remaining questions are whether animals also have the phenomenal features that are the feeling/knowing states of human conscious cognition, and whether the present paradigms can be extended to demonstrate that they do. Thus, the comparative study of metacognition potentially grounds the systematic study of animal consciousness.

Animals↗
PubMed2002

Comparing prototype-based and exemplar-based accounts of category learning and attentional allocation.

Exemplar theory was motivated by research that often used D. L. Medin and M. M. Schaffer's (1978) 5/4 stimulus set. The exemplar model has seemed to fit categorization data from this stimulus set better than a prototype model can. Moreover, the exemplar model alone predicts a qualitative aspect of performance that participants sometimes show. In 2 experiments, the authors reexamined these findings. In both experiments, a prototype model fit participants' performance profiles better than an exemplar model did when comparable prototype and exemplar models were used. Moreover, even when participants showed the qualitative aspect of performance, the exemplar model explained it by making implausible assumptions about human attention and effort in categorization tasks. An independent assay of participants' attentional strategies suggested that the description the exemplar model offers in such cases is incorrect. A review of 30 uses of the 5/4 stimulus set in the literature reinforces this suggestion.

Attention↗
PubMed2002

Exemplar theory's predicted typicality gradient can be tested and disconfirmed.

One of exemplar theory's central predictions concerns the shape of typicality gradients. The typicality gradient it predicts is a consequence of its exemplar-based comparisons and appears no matter how the theory is evaluated. However, this predicted typicality gradient does not fit the empirical typicality gradients obtained in an influential version of the dot-distortion category task, and this is true even when the exemplar model is made more flexible and mathematically powerful. Thus, exemplar theory is disconfirmed in this domain of categorization. In contrast, prototype theories are consistent with the empirically obtained typicality gradients.

Attention↗