The bounded rationality of probability distortion

In decision making under risk (DMR) participants’ choices are based on probability values systematically different from those that are objectively correct. Similar systematic distortions are found in tasks involving relative frequency judgments (JRF). These distortions limit performance in a wide variety of tasks and an evident question is, Why do we systematically fail in our use of probability and relative frequency information? We propose a bounded log-odds model (BLO) of probability and relative frequency distortion based on three assumptions: 1) log-odds: probability and relative frequency are mapped to an internal log-odds scale, 2) boundedness: the range of representations of probability and relative frequency are bounded and the bounds change dynamically with task, and 3) variance compensation: the mapping compensates in part for uncertainty in probability and relative frequency values. We compared human performance in both DMR and JRF tasks to the predictions of the BLO model as well as 11 alternative models, each missing one or more of the underlying BLO assumptions (factorial model comparison). The BLO model and its assumptions proved to be superior to any of the alternatives. In a separate analysis, we found that BLO accounts for individual participants’ data better than any previous model in the DMR literature. We also found that, subject to the boundedness limitation, participants’ choice of distortion approximately maximized the mutual information between objective task-relevant values and internal values, a form of bounded rationality.

The frequency of cortical microstimulation shapes artificial touch

Intracortical microstimulation (ICMS) of the somatosensory cortex evokes vivid tactile sensations and can be used to convey sensory feedback from brain-controlled bionic hands. Changes in ICMS frequency lead to changes in the resulting sensation, but the discriminability of frequency has only been investigated over a narrow range of low frequencies. Furthermore, the sensory correlates of changes in ICMS frequency remain poorly understood. Specifically, it remains to be elucidated whether changes in frequency only modulate sensation magnitude—as do changes in amplitude—or whether they also modulate the quality of the sensation. To fill these gaps, we trained monkeys to discriminate the frequency of ICMS pulse trains over a wide range of frequencies (from 10 to 400 Hz). ICMS amplitude also varied across stimuli to dissociate sensation magnitude from ICMS frequency and ensure that animals could not make frequency judgments based on magnitude. We found that animals could consistently discriminate ICMS frequency up to ∼200 Hz but that the sensory correlates of frequency were highly electrode dependent: On some electrodes, changes in frequency were perceptually distinguishable from changes in amplitude—seemingly giving rise to a change in sensory quality; on others, they were not. We discuss the implications of our findings for neural coding and for brain-controlled bionic hands.

Comparison of the functional food knowledge-awareness levels and consumption frequencies of university students

Aim: The increase in the level of education brings with it many behavioral changes such as healthy nutrition in food purchasing behavior, flexibility against new products. The aim of this study is to create a perspective on whether nutrition and dietetics students' knowledge and awareness levels and functional frequencies are changed with theoretical knowledge. Material and Method: The study consists of 1st and 4th year students in Nutrition and Dietetics Department studying in Private University. The number of students willing to participate voluntarily is 99. 55 (55.6%) of the students were in the 1st grade and 44 (44.4%) were in the 4th grade. The questionnaire used in the study was composed of parts such as demographic characteristics of the students and questions about functional food, functional food sections and the section on measuring the consumption frequency, judgments about functional foods, opinions about whether to prefer functional foods. Results: When the study is examined according to educational level, 16,4% of 1st year students and 77.3% of 4th grade students have previously heard and are familiar with the term functional food. In this case, the rate of hearing the term functional food of 4th grade students was found to be statistically significantly higher than the first year students who have not yet received sufficient academic education. When the percentages of the 1st grade students were not aware of the functional foods and they did not know enough about the function of the product, the rate of not choosing was significantly higher than the 4th grade students.

The bounded rationality of probability distortion

In decision-making under risk (DMR) participants’ choices are based on probability values systematically different from those that are objectively correct. Similar systematic distortions are found in tasks involving relative frequency judgments (JRF). These distortions limit performance in a wide variety of tasks and an evident question is, why do we systematically fail in our use of probability and relative frequency information?We propose a Bounded Log-Odds Model (BLO) of probability and relative frequency distortion based on three assumptions: (1) log-odds: probability and relative frequency are mapped to an internal log-odds scale, (2) boundedness: the range of representations of probability and relative frequency are bounded and the bounds change dynamically with task, and (3) variance compensation: the mapping compensates in part for uncertainty in probability and relative frequency values.We compared human performance in both DMR and JRF tasks to the predictions of the BLO model as well as eleven alternative models each missing one or more of the underlying BLO assumptions (factorial model comparison). The BLO model and its assumptions proved to be superior to any of the alternatives. In a separate analysis, we found that BLO accounts for individual participants’ data better than any previous model in the DMR literature.We also found that, subject to the boundedness limitation, participants’ choice of distortion approximately maximized the mutual information between objective task-relevant values and internal values, a form of bounded rationality.Significance StatementPeople distort probability in decision under risk and many other tasks. These distortions can be large, leading us to make markedly suboptimal decisions. There is no agreement on why we distort probability. Distortion changes systematically with task, hinting that distortions are dynamic compensations for some intrinsic “bound” on working memory. We first develop a model of the bound and the compensation process and then report an experiment showing that the model accounts for individual human performance in decision under risk and relative frequency judgments. Last, we show that the particular compensation in each experimental condition serve to maximize the mutual information between objective decision variables and their internal representations. We distort probability to compensate for our own working memory limitations.

The frequency of cortical microstimulation shapes artificial touch

Intracortical microstimulation (ICMS) of somatosensory cortex evokes vivid tactile sensations and can be used to convey sensory feedback in brain-controlled bionic hands. Changes in ICMS frequency result in discriminable percepts, but the effects of frequency have only been investigated over a narrow range of low frequencies, spanning only a small fraction of that relevant for neuroprosthetics. Furthermore, the sensory correlates of changes in ICMS frequency remain to be elucidated. To fill these gaps, we trained monkeys to discriminate the frequency of ICMS pulse trains over a wide range of frequencies (from 10 to 400 Hz). ICMS amplitude also varied across stimuli to reduce the animals’ reliance on magnitude in making frequency judgments. We found that animals could discriminate ICMS frequency up to about 200 Hz but that the sensory correlates of frequency were highly electrode dependent. We discuss the implications of our findings for neural coding and brain-machine interfaces.

Do We Relatively or Absolutely Overestimate Rare Events?

How good are we at estimating the frequency of rare events? Previous evidence has been mixed: While some studies report well-calibrated frequency judgments, others found rare events to be overestimated. We examined whether the distinctiveness of a rare event fosters overestimation. Distinctiveness may result from exceptional valence, statistical infrequency, or the joint occurrence of two distinct features. Such paired distinctiveness has been found to be particularly salient. We conducted two experiments to investigate the impact of paired distinctiveness and valence on frequency estimations of rare events by combining two paradigms from the decision-making literature and the social psychology literature on stereotypes. The results indicate that rarity alone does not necessarily result in overestimation; rather, the combination of statistical infrequency and small sample sizes (i.e., paired distinctiveness) led participants to overestimate the frequency of a rare event. We were able to rule out alternative explanations such as regression to the mean, but the exact role of outcome valence needs further investigation.