Showing papers by "University of British Columbia published in 1984"
TL;DR: In this paper, the authors present a theory of the inhibition of thought and action to account for people's performance in situations with explicit stop signals, and apply it to several sets of data.
Abstract: Many situations require people to stop or change their current thoughts and actions. We present a theory of the inhibition of thought and action to account for people's performance in such situations. The theory proposes that a control signal, such as an external stop signal or an error during performance, starts a stopping process that races against the processes underlying ongoing thought and action. If the stopping process wins, thought and action are inhibited; if the ongoing process wins, thought and action run on to completion. We develop the theory formally to account for many aspects of performance in situations with explicit stop signals, and we apply it to several sets of data. We discuss the relation between response inhibition and other acts of control in motor performance and in cognition, and we consider how our theory relates to current thinking about attentional control and automaticity.
3,095 citations
2,815 citations
TL;DR: This article showed that infants can discriminate non-native speech contrasts without relevant experience, and that there is a decline in this ability during ontogeny, which is a function of specific language experience.
Abstract: Previous work in which we compared English infants, English adults, and Hindi adults on their ability to discriminate two pairs of Hindi (non-English) speech contrasts has indicated that infants discriminate speech sounds according to phonetic category without prior specific language experience (Werker, Gilbert, Humphrey, & Tees, 1981), whereas adults and children as young as age 4 (Werker & Tees, in press), may lose this ability as a function of age and or linguistic experience. The present work was designed to (a) determine the generalizability of such a decline by comparing adult English, adult Salish, and English infant subjects on their perception of a new non-English (Salish) speech contrast, and (b) delineate the time course of the developmental decline in this ability. The results of these experiments replicate our original findings by showing that infants can discriminate non-native speech contrasts without relevant experience, and that there is a decline in this ability during ontogeny. Furthermore, data from both cross-sectional and longitudinal studies shows that this decline occurs within the first year of life, and that it is a function of specific language experience. © 2002 Published by Elsevier Science Inc.
2,438 citations
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TL;DR: In a noncooperative equilibrium, the terms of trade move against the subsidizing country, but its welfare can increase because, under imperfect competition, price exceeds the marginal cost of exports as discussed by the authors.
Abstract: Countries often perceive themselves as being in competition with each other for profitable international markets. In such a world export subsidies can appear as attractive policy tools, from a national point of view, because they improve the relative position of a domestic firm in noncooperative rivalries with foreign firms, enabling it to expand its market share and earn greater profits. In effect, subsidies change the initial conditions of the game that firms play. The terms of trade move against the subsidizing country, but its welfare can increase because, under imperfect competition, price exceeds the marginal cost of exports. International noncooperative equilibriumis characterized by such subsidies on the part of exporting nations, even though they are jointly suboptimal.
1,742 citations
TL;DR: A condensed-matter analog of (2+1)-dimensional electrodynamics is constructed in this article, and the consequences of a recently discovered anomaly in such systems are discussed in detail.
Abstract: A condensed-matter analog of (2+1)-dimensional electrodynamics is constructed, and the consequences of a recently discovered anomaly in such systems are discussed.
1,573 citations
TL;DR: Four experiments on the ability to inhibit responses in simple and choice reaction time (RT) tasks were reported, and different methods of selecting stop-signal delays were compared to equate the probability of inhibition in the two tasks.
Abstract: This article reports four experiments on the ability to inhibit responses in simple and choice reaction time (RT) tasks. Subjects responding to visually presented letters were occasionally presented with a stop signal (a tone) that told them not to respond on that trial. The major dependent variables were (a) the probability of inhibiting a response when the signal occurred, (b) mean and standard deviation (SD) of RT on no-signal trials, (c) mean RT on trials on which the signal occurred but subjects failed to inhibit, and (d) estimated RT to the stop signal. A model was proposed to estimated RT to the stop signal and to account for the relations among the variables. Its main assumption is that the RT process and the stopping process race, and response inhibition depends on which process finishes first. The model allows us to account for differences in response inhibition between tasks in terms of transformations of stop-signal delay that represent the relative finishing times of the RT process and the stopping process. The transformations specified by the model were successful in group data and in data from individual subjects, regardless of how delays were selected. The experiments also compared different methods of selecting stop-signal delays to equate the probability of inhibition in the two tasks.
1,371 citations
TL;DR: A series of seven studies explored an alternative possibility that the concept of emotion is better understood from a prototype perspective than from a classical perspective as discussed by the authors, and it was argued that membership in emotion is a matter of degree rather than all or none (that the concept has an internal structure) and that no sharp boundary separates members from nonmembers.
Abstract: SUMMARY Many have sought but no one has found a commonly acceptable definition for the concept of emotion. Repeated failure raises the question whether a definition is possible, at least a definition in the classical sense of individually necessary and jointly sufficient attributes. A series of seven studies explored an alternative possibility that the concept of emotion is better understood from a prototype perspective than from a classical perspective. Specifically it is argued that membership in the concept of emotion is a matter of degree rather than all-or-none (that the concept has an internal structure) and that no sharp boundary separates members from nonmembers (that the concept has fuzzy boundaries). As hypothesized, the concept of emotion has an internal structure: happiness, love, anger, fear, awe, respect, envy, and other types of emotion can be reliably ordered from better to poorer examples of emotion. In turn, an emotion's goodness of example (prototypicality) ranking was found to predict how readily incomes to mind when one is asked to list emotions, how likely it is to be labeled as an emotion when one is asked what sort of thing it is, how readily it can be substituted for the word emotion in sentences without their sounding unnatural, and the degree to which it resembles other emotion categories in terms of shared features. In response to an argument made by Armstrong, Gleitman and Gleitman (1983), the evidence for internal structure is acknowledged not to imply fuzzy boundaries. Thus, it was further shown that the concept of emotion, and several other of Rosch's prototypically organized concepts, lacks sharp boundaries and thus can be empirically distinguished from classically defined concepts: Peripheral members of classical concepts but not of fuzzy concepts are nonetheless unequivocal members of the concept. Finally, implications of a prototype view for the psychology, of emotion are discussed. Issues raised include extension of the prototype analysis to anger, fear, and other types of emotion; scientific versus everyday folk concepts; and emotion concepts versus emotion events.
801 citations
01 Jan 1984
TL;DR: In this paper, the currency on loan is model theoretic in the sense that a database can be viewed as a particular kind of first order interpretation, and query evaluation is a process of truth functional evaluation of first-order formulae with respect, to this interpretation.
Abstract: Insofar as database theory can be said to owe a debt to logic, the currency on loan is model theoretic in the sense that a database can be viewed as a particular kind of first order interpretation, and query evaluation is a process of truth functional evaluation of first order formulae with respect, to this interpretation. It is this model theoretic paradigm which leads, for example, to many valued propositional logics for databases with null values.
595 citations
TL;DR: WALKER as discussed by the authors reviewed studies comparing the development of moral reasoning between the sexes and concluded that the overall pattern is one of nonsignificant sex differences in moral reasoning in childhood and adolescence.
Abstract: WALKER, LAWRENCE J. Sex Differences in the Development of Moral Reasoning: A Critical Review. CHILD DEVELOPMENT, 1984, 55, 677-691. In this article the bases for recent allegations of sex bias in Kohlberg's theory of moral development are discussed. Studies comparing the development of moral reasoning between the sexes are then reviewed. Only a few inconsistent sex differences have been found in childhood and adolescence. Some studies indicate that, in adulthood, males evidence higher moral development than females, but in these studies sex differences are confounded with differences in level of education and occupation. A metaanalysis (a statistical procedure for combining findings) supported the conclusion that the overall pattern is one of nonsignificant sex differences in moral reasoning. Discussion focused on implications for moral development theory and research.
565 citations
TL;DR: This review summarizes what is presently known about the biological activities of lignans and specifically inhibit certain enzymes in angiosperms and gymnosperms.
520 citations
TL;DR: The authors speculate that runners are susceptible to Achilles tendinitis with peritendinitis due to micro- trauma produced by the eccentric loading of fatigued muscle, excess pronation producing whipping action of the Achilles tendon, and/or vascular blanching.
Abstract: One hundred nine runners were treated conservatively without immobilization for overuse injury to the Achilles tendon. Treatment strategies were directed toward rehabilitation of the gastrocnemius/soleus muscle-tendon unit, control of inflammation and pain, and control of biomechanical parameters. One fair, 12 good, and 73 excellent results were reported, with a mean recovery time of 5 weeks. Followup was incomplete in 23 cases. The three most prevalent etiological factors were overtraining (82 cases), functional overpronation (61 cases), and gastrocnemius/soleus insufficiency (41 cases). The authors speculate that runners are susceptible to Achilles tendinitis with peritendinitis due to microtrauma produced by the eccentric loading of fatigued muscle, excess pronation producing whipping action of the Achilles tendon, and/or vascular blanching of the Achilles tendon produced by conflicting internal and external rotatory forces imparted to the tibia by simultaneous pronation and knee extension. Virtually all cases of Achilles tendon injury appear to result from structural or dynamic disturbances in normal lower leg mechanics and require active treatment regimens which attempt to establish normal function to prevent recurrence.
TL;DR: Nerve fiber counts of 16 normal human optic nerves from subjects aged 3.5 to 82 years showed a significant effect of age, and the delay between death or enucleation and fixation also significantly affected the result.
TL;DR: Five general routes for the preparation of polyoxyethylene derivatives are described and potential applications to catalysis, cell purifications, and other areas are discussed briefly.
Abstract: Five general routes for the preparation of polyoxyethylene [generally referred to as poly(ethylene glycol) or PEG] derivatives are described. These routes are (1) nucleophilic displacements with the alkoxide of PEG, (2) nucleophilic displacement on PEG–tosylate, –mesylate, or –bromide, (3) reductive amination of PEG–aldehyde, (4) reductive amination of PEG–amine, and (5) nucleophilic displacements on the s-triazine derivatives prepared from s-triazine trichloride (cyanuric chloride) and PEG. Eighteen derivatives are prepared and potential applications to catalysis, cell purifications, and other areas are discussed briefly.
TL;DR: In this article, the nature of the interaction between a quantum field and an accelerating particle detector is analyzed from the point of view of an inertial observer, and it is shown in detail for the simple case of a two-level detector how absorption of a Rindler particle corresponds to emission of a Minkowski particle.
Abstract: The nature of the interaction between a quantum field and an accelerating particle detector is analyzed from the point of view of an inertial observer. It is shown in detail for the simple case of a two-level detector how absorption of a Rindler particle corresponds to emission of a Minkowski particle. Several apparently paradoxical aspects of this process related to causality and energy conservation are discussed and resolved.
TL;DR: In this paper, it was shown that these regions can behave as rubber networks and exhibit rubber-like or entropy elasticity, which is similar to the properties of the non-crystalline regions of spider silk.
Abstract: The silks produced by spiders are exceptional structural materials. Although their tensile strengths are similar to those of cellulose, collagen and chitin, their extensibilities are considerably greater1,2. Thus, the energy required to break spider silk (that is, its toughness) can be 10 times greater than for these other biological materials. The silks are crystalline proteins, with substantial portions of their polypeptide chains forming crystallites of stacked β -pleated sheets3–6. However, the extensibility of silk is attributed to noncrystalline regions, which appear amorphous on X-ray diffraction7,8. The mechanical properties and macromolecular conformation of these amorphous regions have been the subject of much speculation1,2,7–10, but little direct experimentation. Here we show that these regions can behave as rubber networks and exhibit rubber-like or entropy elasticity.
TL;DR: In this article, the mechanical properties of three types of cellular solids (flexible, plastic and brittle) have been measured as a function of density; the results are compared with models for the stiffness, strength and densification; and constitutive laws are developed.
TL;DR: The levels of DMT and beta-carbolines found in the ayahuasca samples examined in the present study were an order of magnitude greater than the levels reported in a previous study, which indicated that their effects in combination are additive, rather than synergistic or antagonistic.
TL;DR: Results of the present shadowing study, involving the recognition and spelling of previously unattended homophones, suggest an affirmative answer to this question.
Abstract: The effects of memory for unattended events—for example, events that occur while a person is asleep, anesthetized, or selectively attending to other ongoing events, as in a speech-shadowing task—are rarely revealed in tests of retention that require remembering to be deliberate or intentional. Might such effects become evident in tests that do not demand awareness of remembering? Results of the present shadowing study, involving the recognition and spelling of previously unattended homophones, suggest an affirmative answer to this question.
TL;DR: The findings suggest that an executive's propensity to adopt a particular strategic posture depends on his perceptions of how well his firm can control its environment and on the costs of introducing change into the organization.
Abstract: This paper describes an empirical study that examines the relationship between the type of external environment in which a firm operates and the repertoire of strategic responses the firm develops to cope with crises. The findings suggest that an executive's propensity to adopt a particular strategic posture depends on his perceptions of how well his firm can control its environment and on the costs of introducing change into the organization.
TL;DR: In this paper, the notion of flexibility in a sequential decision context, and its value to the amount of information an agent expects to receive, is discussed, and a basic consideration in this choice is the recognition that beliefs about the risks governing these payoffs may change.
Abstract: The preserving of flexibility when faced with uncertainty is a neglected aspect of behaviour under risk. Yet it is an important factor in decisions to hold liquid assets or delay irreversible investment. This paper formalizes the notion of flexibility in a sequential decision context, and relates its value to the amount of information an agent expects to receive. A rudimentary money demand model is developed embodying these ideas, and the history of flexibility as an economic concept is traced. Choices are frequently made between alternatives that imply different degrees of future commitment-between a short-term investment that leaves future options open, for example, and a long-term one that, by its very nature, forecloses those options. The relative attractiveness of the two depends on their probability distributions of payoffs over time. A basic consideration in this choice is the recognition that beliefs about the risks governing these payoffs may change. Current doubts may be partially resolved in the near future. This prospect decreases the attractiveness of the longer term commitment, in that one is able to respond less fully to new information, and, even if it does not directly affect the risks associated with shorter term choices, enhances their appeal. This paper formalizes the above remarks by establishing connections between the following two (partial) orderings: The first is an ordering based on variability of beliefs. One set of beliefs is more variable than another if more final risk is resolved at an intermediate stage. The more one expects to learn by an intermediate period, relative to what one knows today, the more variation one is anticipating in beliefs about the final outcome. The second is an ordering of current actions, or positions, based on flexibility. One position is more flexible than another if it leaves available a larger set of future positions at any given level of cost. These two orderings are incorporated in a simple sequential decision model to suggest the following behavioural principle: The more variable are a decision-maker's beliefs, the more flexible is the position he will choose. This principle potentially applies whenever (i) there will be opportunities to act after further information is received, and (ii) current actions influence either the attractiveness or availability of different future actions.
Patent•
20 Jun 1984TL;DR: In this paper, a modem is provided for use on a line carrying an A.C. signal, where a pseudorandom code generator is used to produce a pseudo-random code signal of a bit rate an integral multiple of the signal frequency.
Abstract: A modem which may operate as a transmitter or receiver, is provided for use on a line carrying an A.C. signal. The modem comprises a pseudorandom code generator which produces a pseudorandom code signal of a frequency an integral multiple of the A.C. signal frequency. Synchronization means synchronizes the code signal with the A.C. signal. Preferably a coherent system is provided in which a data signal involved has a bit rate an integral multiple of the A.C. signal frequency and in which a carrier generator is additionally provided to produce a carrier signal of a frequency an integral multiple of the A.C. signal frequency. In such case, the synchronization means also synchronizes the data bit and carrier signals with the A.C. signal.
TL;DR: The perceptual processing of arrows and triangles and of their component angles and lines was explored and the results suggest that some analysis of shapes into simpler parts occurs preattentively, because these parts can recombine to form illusory conjunctions when attention is divided.
Abstract: The perceptual processing of arrows and triangles and of their component angles and lines was explored in a number of different tasks. The results suggest that some analysis of shapes into simpler parts occurs preattentively, because these parts can recombine to form illusory conjunctions when attention is divided. The presence of "emergent features," such as closure or arrow junctions, was inferred from predicted correlations in the pattern of performance across tasks and across individual subjects. Thus triangles (for most subjects) and arrows (for some subjects) behave as if they had a perceptual feature that is absent from their parts and that mediates parallel detection in search and easy texture segregation. For some subjects, circles could apparently supply the additional feature (presumably closure) required to form illusory triangles from their component lines, whereas for other subjects circles had no effect. The fact that triangle lines can form illusory conjunctions with another shape makes it unlikely that triangles are perceived holistically and strengthens the interpretation that relies on emergent features.
TL;DR: Generalized reduction of nerve fibers with or without localized defects was more common in patients with glaucoma than in those with ocular hypertension whose abnormal findings were primarily localized defects.
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TL;DR: In a noncooperative equilibrium, the terms of trade move against the subsidizing country, but its welfare can increase because, under imperfect competition, price exceeds the marginal cost of exports as mentioned in this paper.
Abstract: Countries often perceive themselves as being in competition with each other for profitable international markets. In such a world export subsidies can appear as attractive policy tools, from a national point of view, because they improve the relative position of a domestic firm in noncooperative rivalries with foreign firms, enabling it to expand its market share and earn greater profits. In effect, subsidies change the initial conditions of the game that firms play. The terms of trade move against the subsidizing country, but its welfare can increase because, under imperfect competition, price exceeds the marginal cost of exports. International noncooperative equilibriumis characterized by such subsidies on the part of exporting nations, even though they are jointly suboptimal.
TL;DR: In this paper, the authors show that for Cournot oligopoly, the optimal response to foreign monopoly is usually a tariff, but a specific subsidy will be optimal if demand is very convex, as with constant elasticity demand.
TL;DR: In this paper, the authors formulated the selection of a monitoring network as a decision problem whose solutions would then be optimal, and applied the theory where the underlying field has a multivariate normal probability structure.
TL;DR: State of the art and recent developments in computational linear algebra, including linear systems, least squares techniques, the singular value decomposition, and eigenvalue problems are reviewed briefly.