Decision processes in temporal discrimination

The processing dynamics underlying temporal decisions and the response times they generate have received little attention in the study of interval timing. In contrast, models of other simple forms of decision making have been extensively investigated using response times, leading to a substantial disconnect between temporal and non-temporal decision theories. An overarching decision-theoretic framework that encompasses existing, non-temporal decision models may, however, account both for interval timing itself and for time-based decision-making. We sought evidence for this framework in the temporal discrimination performance of humans tested on the temporal bisection task. In this task, participants retrospectively categorized experienced stimulus durations as short or long based on their perceived similarity to two, remembered reference durations and were rewarded only for correct categorization of these references. Our analysis of choice proportions and response times suggests that a two-stage, sequential diffusion process, parameterized to maximize earned rewards, can account for salient patterns of bisection performance. The first diffusion stage times intervals by accumulating an endogenously noisy clock signal; the second stage makes decisions about the first-stage temporal representation by accumulating first-stage evidence corrupted by endogenous noise. Reward-maximization requires that the second-stage accumulation rate and starting point be based on the state of the first-stage timer at the end of the stimulus duration, and that estimates of non-decision-related delays should decrease as a function of stimulus duration. Results are in accord with these predictions and thus support an extension of the drift–diffusion model of static decision making to the domain of interval timing and temporal decisions.     

Group processes in computer-mediated communication

Three experiments explored the effects of computer-mediated communication on communication efficiency, participation, interpersonal behavior, and group choice. Groups of three members were asked to reach consensus on career choice problems; they communicated face-to-face and in simultaneous computer-mediated discussions or through computer mail. When groups were linked by computer, group members made fewer remarks than they did face-to-face and took longer to make their group decisions. Social equalization was higher in computer-mediated groups in that group members participated more equally in discussions. Computer-mediated groups also exhibited more uninhibited behavior—using strong and inflammatory expressions in interpersonal interactions. Decisions of computer-mediated groups shifted further away from the members' initial individual choices than group decisions which followed face-to-face discussions. We discuss the implications of these findings for extension of theories about group interaction and for analyses of the effects of Computers in organizations.     

Decision processes in visual discrimination of line orientation

The contribution of decision factors to the meridional variations in line orientation discrimination was determined for two-alternative forced-choice experimental designs. Using Johnson's (1980) formalization of decision processes in discrimination tasks, we identified three decision factors: the decision rule, memory variance, and criterial noise. In a first experiment, we showed the effect of experimental design on orientation discrimination to be similar at horizontal and oblique standard orientations, indicating that the meridional variations in orientation discrimination were not due to a decision rule anisotropy. In a second experiment, the effect of the interstimulus interval was also found to be similar at both standard orientations, suggesting that the memory variance is isotropic in the orientation domain. The results of two other experiments supported the hypothesis that the meridional variations in orientation discrimination are not due to a criterial noise anisotropy. These different results strongly suggested that the oblique effect in line orientation discrimination is due to sensorial factors rather than to decision factors. Therefore, they further support the hypothesis linking the anisotropy of the preferred orientation distribution of Area 17-S cells (a single physiologically defined class of cells in the primary visual cortex) and the meridional variations in line orientation discrimination.     

Decision processes in children's recognition memory

Kindergarteners and third graders were given a continuous recognition memory task involving two-digit numbers. In addition, a rating scale consisting of photographs of various facial expressions was used to obtain confidence judgments from the Ss. Conventional analyses as well as signal detection analyses of the data revealed the following results: (a) the overall performance of the third graders was superior to that of the kindergarteners; (b) memory strength decreased as the number of intervening items increased; (c) there was no difference in the forgetting rates of the two grade levels; (d) the third graders exhibited a more liberal response bias than the kindergarteners; (e) both the hit rate (probability of correctly labeling an old stimulus as old) and the false-alarm rate (probability of incorrectly labeling a new stimulus as old) increased across blocks of items; (f) the increases in the hit rate and the false-alarm rate over blocks were due to a change in criterion from a relatively conservative level to a more lenient one; (g) the lower the S's level of confidence in judging an item as old, the lower was the probability of that item actually being old; (h) the third graders were better than the kindergarteners at gauging the accuracy of their recognition responses. It was concluded that with respect to recognition memory, chidren as young as $\text{5}\text{1}\text{2}$ years old are capable, to some extent, of monitoring their own memory states.     

Talking nets: a multiagent connectionist approach to communication and trust between individuals

A multiagent connectionist model is proposed that consists of a collection of individual recurrent networks that communicate with each other and, as such, is a network of networks. The individual recurrent networks simulate the process of information uptake, integration, and memorization within individual agents, and the communication of beliefs and opinions between agents is propagated along connections between the individual networks. A crucial aspect in belief updating based on information from other agents is the trust in the information provided. In the model, trust is determined by the consistency with the receiving agents' existing beliefs and results in changes of the connections between individual networks, called trust weights. These weights lead to a selective propagation and thus to the filtering out of less reliable information, and they implement H. P. Grice's (1975) maxims of quality and quantity in communication. The unique contribution of communicative mechanisms beyond intrapersonal processing of individual networks was explored in simulations of key phenomena involving persuasive communication and polarization, lexical acquisition, spreading of stereotypes and rumors, and a lack of sharing unique information in group decisions.     

Dyadic processes of disclosure and reciprocity in bargaining with communication

We offer a study revealing the mechanisms through which communication helps actual bargaining behavior outperform economic predictions. The possibility of individually strategic behavior in the presence of private information leads to game‐theoretic predictions of less than full efficiency. We present a one‐stage, simultaneous offers bargaining game in which buyers and sellers have independent, privately held valuations for the item being sold (i.e. a bilateral auction with two‐sided private information). In three communication treatments, parties are: (a) allowed face‐to‐face communication prior to submitting offers; (b) allowed written communication prior to submitting offers; or (c) allowed no‐communication prior to submitting offers. When parties are allowed pre‐play communication, we find nearly full efficiency (98%). We examine two systematically predictable aspects of dyadic interaction—disclosure and reciprocity—to explain how negotiators achieve this efficiency. Copyright © 2002 John Wiley & Sons, Ltd.     

Decision processes in discrimination: fundamental misrepresentations of signal detection theory.

A new approach to studying decision making in discrimination tasks is described that does not depend on the technical assumptions of signal detection theory (e.g., normality of the encoding distributions). In 3 different experiments, results of these new distribution-free tests converge on a single, surprising conclusion: response biases had substantial effects on the encoding distributions but no effect on the decision rule, which was uniformly unbiased in equal and unequal base rate conditions and in symmetric and asymmetric payoff conditions. This seemingly paradoxical result is fundamentally inconsistent with the entire family of signal detection theory models, raising some important questions about the significance of many published results in the human performance literature.     

Social processes in communication and cognition in callitrichid monkeys: a review

Studies of vocal development in nonhuman primates have found little evidence for plasticity in vocal production, somewhat more for usage of calls, with the greatest plasticity arising in response to calls of others. Generally, similar results were obtained with callitrichid monkeys, the marmosets and tamarins, but with several interesting exceptions. Infant pygmy marmosets show babbling behavior with improvement in adult call structure related to the amount and diversity of babbling. Adult marmosets alter call structure in response to changes in social partners, and wild marmosets have vocal dialects and modify call structure according to how far they are from other group members, suggesting the potential to modify call structure in different social and environmental contexts, though direct learning of novel vocalizations has not been observed. Infant cotton-top tamarins do not produce adult-like calls in appropriate contexts, at least in the first few months of life, but through food sharing from adults infants learn about appropriate foods and the appropriate contexts for food vocalizations. Tamarins modify call structure and usage with changes in social status. Tamarins, unlike other monkeys tested, can learn to avoid noxious foods through observation of other group members, and can learn about novel food locations. Recent studies provide evidence of contextual imitation in marmosets. The plasticity in vocal communication and evidence of social learning in marmosets and tamarins relative to other monkeys may be related to the cooperative breeding system of marmosets and tamarins. With a high degree of behavioral coordination among group members, there is a priority on monitoring signals and behavior of others and adjusting one's own signals and behavior. This creates the context for vocal plasticity and social learning. Accepted after revision: 23 May 2001 Electronic Publication