How western scrub-jays (Aphelocoma californica) select a nut: effects of the number of options, variation in nut size, and social competition among foragers

Western scrub-jays (Aphelocoma californica) often visually assess and handle several whole (unshelled) peanuts before selecting one to transport and cache; this behavior is a search for a preferred heavy nut. I repeatedly video-taped individually identifiable jays as they landed on a feeding platform and chose from presentations of peanuts that varied in the number of items or in the distribution of sizes. I examined how differences among these presentations and a bird’s social status affected the amount of assessment and the economic consequences of choice. I also examined the specific patterns of handling peanuts, called sampling, to quantify the degree to which sampling sequences were typified by repeated comparisons among sampled peanuts (retrospective sampling), or sequential assessment and rejection of peanuts (prospective sampling). Peanut assessment was more extensive and prospective when there were many options from which to choose than when there were few. Peanut assessment was more extensive and retrospective when options were similar in size than when they varied. Scrub-jays were more likely to make repeated comparisons immediately before selecting a peanut than elsewhere in a sampling sequence. Subordinate scrub-jays, who were at the greatest risk of pre-emption by competitors, assessed peanuts less extensively and were more prospective in their sampling than dominants. Unless peanuts were very similar in size, jays were more accurate at selecting a high-quality peanut and achieved a higher rate of food storage than if they had not assessed. These results show that scrub-jays can adaptively modify how they search to improve their rate of food storage, and also suggest some of the specific search tactics used by jays when assessing peanuts. Received: 26 April 1999 / Accepted after revision: 10 October 1999     

A hierarchical bayesian model of human decision-making on an optimal stopping problem

We consider human performance on an optimal stopping problem where people are presented with a list of numbers independently chosen from a uniform distribution. People are told how many numbers are in the list, and how they were chosen. People are then shown the numbers one at a time, and are instructed to choose the maximum, subject to the constraint that they must choose a number at the time it is presented, and any choice below the maximum is incorrect. We present empirical evidence that suggests people use threshold-based models to make decisions, choosing the first currently maximal number that exceeds a fixed threshold for that position in the list. We then develop a hierarchical generative account of this model family, and use Bayesian methods to learn about the parameters of the generative process, making inferences about the threshold decision models people use. We discuss the interesting aspects of human performance on the task, including the lack of learning, and the presence of large individual differences, and consider the possibility of extending the modeling framework to account for individual differences. We also use the modeling results to discuss the merits of hierarchical, generative and Bayesian models of cognitive processes more generally.     

The Enhanced Agentic Diversity Perspective (EADP): An appeal for Co-creating an accommodative social space so that diversity unlocks innovativeness rather than problems

We propose in this article an Enhanced Agentic Diversity Perspective (EADP), which is derived from the concept of agentic resources in social relational theory. EADP recognizes that all human beings are equally agents, that agentic expressions differ due to variation of individual access to power resources (individual, relational and cultural) and that the current social conditions serve to promote agentic diversity by enhancing all the three domains of power resources. In addition, EADP comprises a proposal for the development of accommodative social spaces. We argue that only in an accommodative social space can diversity unlock innovation; otherwise, it serves as a source for conflict. A constructive, nonhierarchical account of diversity, such as EADP is needed under current social conditions for the optimal becoming of idiosyncratic human agents as well as human society as a whole.     

Context effects in multi-alternative decision making: empirical data and a Bayesian model

For decisions between many alternatives, the benchmark result is Hick's Law: that response time increases log-linearly with the number of choice alternatives. Even when Hick's Law is observed for response times, divergent results have been observed for error rates-sometimes error rates increase with the number of choice alternatives, and sometimes they are constant. We provide evidence from two experiments that error rates are mostly independent of the number of choice alternatives, unless context effects induce participants to trade speed for accuracy across conditions. Error rate data have previously been used to discriminate between competing theoretical accounts of Hick's Law, and our results question the validity of those conclusions. We show that a previously dismissed optimal observer model might provide a parsimonious account of both response time and error rate data. The model suggests that people approximate Bayesian inference in multi-alternative choice, except for some perceptual limitations.     

Obtaining the best value for money in adaptive sequential estimation

In [Kujala, J. V., Richardson, U., &; Lyytinen, H. (2010). A Bayesian-optimal principle for learner-friendly adaptation in learning games. Journal of Mathematical Psychology, 54(2), 247–255], we considered an extension of the conventional Bayesian adaptive estimation framework to situations where each observable variable is associated with a certain random cost of observation. We proposed an algorithm that chooses each placement by maximizing the expected gain in utility divided by the expected cost. In this paper, we formally justify this placement rule as an asymptotically optimal solution to the problem of maximizing the expected utility of an experiment that terminates when the total cost overruns a given budget. For example, the cost could be defined as the random time taken by each trial in an experiment, and one might wish to maximize the expected total information gain over as many trials as can be completed in 15 min. A simple, analytically tractable example is considered.     

Children With Conduct Problems and Co-occurring ADHD: Behavioral Improvements Following Parent Management Training

To scale up evidence-based treatment of conduct problems, parent management training, Oregon model (PMTO) has been disseminated throughout Norway. This study examined whether Attention Deficit Hyperactivity Disorder (ADHD) predicted the outcomes of PMTO. Of 253 children and families, 97 were reported to have an ADHD diagnosis. Although different at intake, the groups with and without ADHD had close to an equal change in behavioral status following treatment. Maternal depression and family income predicted the combined group's behavior following PMTO. The study indicates that reductions in conduct problems following PMTO are of the same magnitude in children with or without ADHD. However, some characteristics may differentially predict outcomes for children with combined problems.     

Feeling Good,but Lacking Autonomy: Closed-Mindedness on Social and Moral Issues in New Religious Movements

According to previous research, New Religious Movements (NRMs) seem to have a positive effect on the mental health of members who join NRMs with some previous affective, cognitive or other vulnerabilities. The present study investigates the other, less positive, side of the psychology of NRMs, i.e. elements that may be an obstacle to optimal development, such as rigidity and low autonomy. In comparison to non-NRM members, members of various NRMs in Belgium (N = 120) were found to be low in quest religious orientation (Altemeyer and Hunsberger, Int J Psychol Religion 2:113–133, 1992), to privilege conservation values to the detriment of openness to change values (Schwartz, Advances in experimental social psychology (vol 25, pp. 1–65). Orlando, FL: Academic Press, 1992), to show submissiveness to authority in hypothetical situations (projective measure), and to highly moralize judgments of transgression relative to conventional domains (Turiel, The development of social knowledge: Morality and social convention. Cambridge: Cambridge University Press, 1983). Discussion points out the idea that rigidity and restriction of autonomy may be the price to be paid for the structuring role NRMs play with regard to previous vulnerabilities.

There is a 60% probability,but I am 70% certain: communicative consequences of external and internal expressions of uncertainty

Current theories of probability recognise a distinction between external (un)certainty (frequentistic probabilities) and internal (un)certainty (degrees of belief). The present studies investigated this distinction in lay people's judgements of probability statements formulated to suggest either an internal (“I am X% certain”) or an external (“It is X% certain” or “There is an X% probability”) interpretation. These subtle differences in wording influenced participants' perceptions and endorsements of such statements, and their impressions of the speaker. External expressions were seen to signal more reliable task duration estimates, and a lower degree of external than internal certainty was deemed necessary to advise a course of action. In conversations about football, internal expressions were perceived as signalling more personal interest, and were expected to be on the average 10% higher than corresponding external probabilities. Finally, people who reported their outcome expectations for two major sports events let their degree of interest in these events influence their internal but not their external certainty. These results have implications for the communication of uncertainty and probability.     

Does surrounding traffic benefit from an assisted driver with traffic light assistance system?

Traffic light assistance systems enable drivers more energy and time efficient driving behavior at signalized intersections. However, most vehicles will not be equipped with such systems in the next years. These unequipped vehicles’ drivers (UVDs) may benefit from assisted drivers, if they would adapt their behavior. This paper outlines how UVDs (N = 60) interpreted and reacted to a driver with traffic light assistance system. We used a multi-driver simulator with three drivers driving in a car-following scenario. The lead driver was not a participant, but a confederate who was followed by two UVDs. The confederate was apparently equipped either with or without a traffic light assistance system. The traffic light assistance system consisted of two functionalities: a Green Light Optimal Speed Advisory and a start-up assistance system with two different parametrizations. These functionalities aimed at preventing unnecessary changes in speed and reducing the start-up lost time after signal change. The results showed that UVDs benefited from the driving behavior of the confederate with traffic light assistance system. However, the assisted driving behavior was hardly understood and partly rated as aversive by the UVDs. We discuss how to enhance behavioral adaptation of UVDs. We also outline which negative consequences may result from encounters of driver with systems and UVDs. We assume that how UVDs react towards drivers with systems may be one factor contributing to a successful launch of such systems.