Peter Kvam

Michigan State University, Psychology, Graduate Student

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Steven Pinker

Harvard University

Selis Onel

Hacettepe University

John Johnson

Pennsylvania State University

Armando Marques-Guedes

UNL - New University of Lisbon

John Sutton

Macquarie University

Eros Carvalho

Universidade Federal do Rio Grande do Sul

Fabio Cuzzolin

Oxford Brookes University

Venceslau Tavares Costa Filho

Universidade de Pernambuco - UPE (Brasil)

Noel Struchiner

PUC-RJ

Thomas L Webb

The University of Sheffield

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Papers by Peter Kvam

Strength and weight: The determinants of choice and confidence

Cognition, 2016

Evidence for different hypotheses is often treated as a singular construct, but it can be dissoci... more Evidence for different hypotheses is often treated as a singular construct, but it can be dissociated into two parts: its strength, the proportion of pieces of information favoring one hypothesis; and its weight, the total number of pieces of information available. However, cognitive and neural models of evidence accumulation often make a proportional representation assumption, implying that people take these two factors into account equally when making their decisions and judgments. We examine this assumption by directly manipulating the number of samples and the proportion favoring either of two alternatives in dynamic decision making and judgment tasks. The results suggest that people tend to over-emphasize the strength of evidence relative to its weight in both an optional-stopping decision task and a probability judgment task. In a drift-diffusion model, this is reflected by drift rates that are determined foremost by strength with a smaller influence of weight. This result cha...

Computational evolution of decision-making strategies

Most research on adaptive decision-making takes a strategy-first approach, proposing a method of ... more Most research on adaptive decision-making takes a strategy-first approach, proposing a method of solving a problem and then examining whether it can be implemented in the brain and in what environments it succeeds. We present a method for studying strategy development based on computational evolution that takes the opposite approach, allowing strategies to develop in response to the decision-making environment via Darwinian evolution. We apply this approach to a dynamic decision-making problem where artificial agents make decisions about the source of incoming information. In doing so, we show that the complexity of the brains and strategies of evolved agents are a function of the environment in which they develop. More difficult environments lead to larger brains and more information use, resulting in strategies resembling a sequential sampling approach. Less difficult environments drive evolution toward smaller brains and less information use, resulting in simpler heuristic-like s...

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Interference in Choice and Confidence: Using the Quantum Random Walk to Model Distributions of Confidence

Lecture Notes in Computer Science, 2014

ABSTRACT In this paper, we examine the effect of making a choice on subsequent confidence. Using ... more ABSTRACT In this paper, we examine the effect of making a choice on subsequent confidence. Using a simple binary forced-choice perceptual task, we show that committing to a decision results in perturbed probability (confidence) judgments compared to a control condition where no decision is elicited, suggesting that committing to a decision interferes with subsequent information processing. Current classical probability models of decision-making and confidence do not predict this interference effect, but it arises naturally out of a quantum random walk model. We show that this model provides a better fit to the data and provides novel predictions of interference as well as improved confidence accuracy following a decision.

A new approach to modeling Figure-Ground Organization

Journal of Vision, 2010

Interference effects of choice on confidence: Quantum characteristics of evidence accumulation

by Jerome Busemeyer and Peter Kvam

Decision-making relies on a process of evidence accumulation which generates support for possible... more Decision-making relies on a process of evidence accumulation which generates support for possible hypotheses. Models of this process derived from classical stochastic theories assume that information accumulates by moving across definite levels of evidence, carving out a single trajectory across these levels over time. In contrast, quantum decision models assume that evidence develops over time in a superposition state analogous to a wavelike pattern and that judgments and decisions are constructed by a measurement process by which a definite state of evidence is created from this indefinite state. This constructive process implies that interference effects should arise when multiple responses (measurements) are elicited over time. We report such an interference effect during a motion direction discrimination task. Decisions during the task interfered with subsequent confidence judgments, resulting in less extreme and more accurate judgments than when no decision was elicited. These results provide qualitative and quantitative support for a quantum random walk model of evidence accumulation over the popular Markov random walk model. We discuss the cognitive and neural implications of modeling evidence accumulation as a quantum dynamic system. confidence | Markov | decision-making | cognitive model | random walk D ecisions in a wide range of tasks (e.g., inferring the presence or absence of a disease, the guilt or innocence of a suspect, and the left or right direction of enemy movement) require evidence to be accumulated in support of different hypotheses. Arguably, the most successful theory of evidence accumulation in humans and other animals is Markov random walk (MRW) theory (and diffusion models, their continuous space extensions) (1, 2). MRWs can be viewed as psychological implementations of a first-order Bayes-ian inference process that assigns a posterior probability to each hypothesis (3). MRWs can account for choices, response times, and confidence for a variety of different decision types (2, 4). Moreover, these models of the accumulation process have been connected to neural activity during decision-making (5, 6). According to MRW models, when deciding between two hypotheses , the cumulative evidence for or against each hypothesis realizes different levels at different times to generate a single particle like trajectory of evidence levels across time (Fig. 1). At any point in time, the decision-maker has a definite level of evidence, and choices are made by comparing the existing level of evidence against a criterion. Evidence above the criterion favors one option, and evidence below it favors the alternative. Other responses are modeled in a similar manner; for example, confidence ratings are modeled by mapping evidence states onto one or more ratings (4). However, this idea that judgments and decisions are simply read out from the existing level of evidence—henceforth referred to as the " read-out " assumption—is inconsistent with the well-established idea that preferences and beliefs are constructed rather than revealed by judgments and decisions (7). We present an alternative model of choice and judgment based on quantum random walk (QRW) theory (8–11), which posits that preferences and beliefs are constructed when a judgment or decision is made. Note that this work does not make the assumption that the brain is a quantum computer; instead, we simply use the mathematics of quantum theory to explain and predict human behavior. According to QRW theory, at any point in time before a decision, the decision-maker is in a superposition state that is not located at a single level of evidence. Instead, each level of evidence has a potential to be expressed, formalized as a probability amplitude (Fig. 1). New information changes the amplitudes, producing a wavelike process that moves the amplitude distribution across time. In some ways the QRW is like a second-order Bayesian model (12). According to the latter, the decision-maker assigns a probability (rather than an amplitude) to each level of evidence for each hypothesis. However, like the MRW model, second-order Bayesian models are perfectly compatible with the read-out assumption, and as an optimal model, this would suggest that a decision should not change the probability assigned to each evidence level. In contrast, a QRW, like all quantum models of cognition (13), treats a judgment or decision as a measurement process that constructs a definite state from an indefinite (superposition) state. When a decision is made, the indefinite state collapses onto a set of evidence levels that correspond to the observed choice, producing a definite choice state. Confidence ratings work similarly, with the indefinite state collapsing onto a more specific set of levels corresponding to the observed rating. These different theories of choice and judgment have strong implications for sequences of responses. Consider the situation when decision-makers have to make a choice (e.g., decide that hypothesis A or B is true) and later rate their confidence that a given (usually the chosen) hypothesis is true. According to the read-out assumption, a choice is reported on the basis of existing evidence that does not change the internal state of evidence itself. This applies to the MRW, a second-order Bayesian model, and many other accumulation models as well. Thus, after pooling across a person's choices, the distribution of confidence ratings should be identical to conditions in which the person makes no choice at all. By contrast, the state of the system in a QRW Significance Most cognitive and neural decision-making models—owing to their roots in classical probability theory—assume that decisions are read out of a definite state of accumulated evidence. This assumption contradicts the view held by many behavioral scientists that decisions construct rather than reveal beliefs and preferences. We present a quantum random walk model of decision-making that treats judgments and decisions as a constructive measurement process, and we report the results of an experiment showing that making a decision changes subsequent distributions of confidence relative to when no decision is made. This finding provides strong empirical support for a parameter-free prediction of the quantum model.

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An Empirical Test of Type-Indeterminacy in the Prisoner’s Dilemma

by Peter Kvam and Ariane Lambert-Mogiliansky

Lecture Notes in Computer Science, 2014

ABSTRACT In this paper, we test the type indeterminacy hypothesis by analyzing an experiment that... more ABSTRACT In this paper, we test the type indeterminacy hypothesis by analyzing an experiment that examines the stability of preferences in a Prisoner Dilemma with respect to decisions made in a context that is both payoff and informationally unrelated to that Prisoner Dilemma. More precisely we carried out an experiment in which participants were permitted to make promises to cooperate to agents they saw, followed by playing a Prisoner’s Dilemma game with another, independent agent. It was found that, after making a promise to the first agent, participants exhibited higher rates of cooperation with other agents. We show that a classical model does not account for this effect, while a type indeterminacy model which uses elements of the formalism of quantum mechanics is able to capture the observed effects reasonably well.

Interference effects of choice on confidence: Quantum characteristics of evidence accumulation

Decision making relies on a process of evidence accumulation which generates support for possible... more Decision making relies on a process of evidence accumulation which generates support for possible hypotheses. Models of this process derived from classical stochastic theories assume that information accumulates by moving across definite levels of evidence, carving out a single trajectory across these levels over time. In contrast, quantum decision models assume that evidence develops over time in a superposition state analogous to a wavelike pattern, and that judgments and decisions are constructed by a measurement process by which a definite state of evidence is created from this indefinite state. This constructive process implies that interference effects should arise when multiple responses (measurements) are elicited over time. We report such an interference effect during a motion direction discrimination task. Decisions during the task interfered with subsequent confidence judgments, resulting in less extreme and more accurate judgments than when no decision was elicited. These results provide qualitative and quantitative support for a quantum random walk model of evidence accumulation over the popular Markov random walk model. We discuss the cognitive and neural implications of modeling evidence accumulation as a quantum dynamic system.

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The Effect of Condoms on Penile Vibrotactile Sensitivity Thresholds in Young, Heterosexual Men

by Brandon Hill, Erick Janssen, and Peter Kvam

The Journal of Sexual Medicine, 2014

Investigating the ways in which barrier methods such as condoms may affect penile sensory thresho... more Investigating the ways in which barrier methods such as condoms may affect penile sensory thresholds has potential relevance to the development of interventions in men who experience negative effects of condoms on sexual response and sensation. A quantitative, psychophysiological investigation examining the degree to which sensations are altered by condoms has, to date, not been conducted. Aim. The objective of this study was to examine penile vibrotactile sensitivity thresholds in both flaccid and erect penises with and without a condom while comparing men who do and those who do not report condom-associated erection problems (CAEP). Methods. Penile vibrotactile sensitivity thresholds were assessed among a total of 141 young, heterosexual men using biothesiometry. An incremental two-step staircase method was used and repeated three times for each of four conditions. Intra-class correlation coefficients (ICCs) were calculated for all vibratory assessments. Penile vibratory thresholds were compared using a mixed-model analysis of variance. Main Outcome Measures. Penile vibrotactile sensitivity thresholds with and without a condom, erectile function measured by International Index of Erectile Function Questionnaire, and self-reported degree of erection. Results. Significant main effects of condoms (yes/no) and erection (yes/no) were found. No main or interaction effects of CAEP were found. Condoms were associated with higher penile vibrotactile sensitivity thresholds (F[1,124] = 17.11, P < 0.001). Penile vibrotactile thresholds were higher with an erect penis than with a flaccid penis (F[1,124] = 4.21, P = 0.042). Conclusion. The current study demonstrates the feasibility of measuring penile vibratory thresholds with and without a condom in both erect and flaccid experimental conditions. As might be expected, condoms increased penile vibrotactile sensitivity thresholds. Interestingly, erections were associated with the highest thresholds. Thus, this study was the first to document that erect penises are less sensitive to vibrotactile stimulation than flaccid penises. Hill BJ, Janssen E, Kvam P, Amick EE, and Sanders SA. The effect of condoms on penile vibrotactile sensitivity thresholds in young, heterosexual men. J Sex Med 2014;11:102-106.

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Patterns of Sexual Arousal in Young, Heterosexual Men Who Experience Condom-Associated Erection Problems (CAEP)

by Brandon Hill, Erick Janssen, and Peter Kvam

The Journal of Sexual Medicine, 2014

Condom-associated erection problems (CAEPs) are reported by a substantial number of young men and... more Condom-associated erection problems (CAEPs) are reported by a substantial number of young men and are associated with inconsistent and/or incomplete condom use. The underlying mechanisms of CAEP are not well understood, and research examining the possibility that men who report CAEP differ from other men in their sexual responsivity is lacking. Aim. This study used psychophysiological methods to examine whether men who report CAEP have a higher threshold for sexual arousal, a stronger need for tactile stimulation, and/or more easily lose their sexual arousal due to neutral distractors or performance-related demands. Methods. A total of 142 young, heterosexual men (53% reporting CAEP) were presented with four 3-minute erotic film clips. Three film clips were combined with one of the following manipulations: (i) distraction; (ii) performance demand; or (iii) vibrotactile stimulation. One erotic film clip was presented with no further instructions or manipulations. Main Outcome Measures. Average penile circumference changes during the first, second, and third minute (time) of the erotic film stimuli (condition) were submitted to a mixed-model analysis of variance with condition and time as within-subjects factors and group (CAEP/no-CAEP) as between-subjects factor. Results. Significant main effects of condition and time and a significant interaction of group × time were found. No significant interactions involving condition were found. Men who reported CAEP had smaller erectile responses during the first minute, regardless of film condition, than men who reported no CAEP (F(1,141) = 8.64, P < 0.005). Conclusion. The findings suggest that men with and without CAEP differ in the ease with which they become sexually aroused. Men reporting CAEP needed more time and/or more intense stimulation to become aroused. To our knowledge, this study is the first to use psychophysiological methods to assess sexual responsivity in men who report CAEP. Janssen E, Sanders SA, Hill BJ, Amick E, Oversen D, Kvam P, and Ingelhart K. Patterns of sexual arousal in young, heterosexual men who experience condom-associated erection problems (CAEP).

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What's the predicted outcome? Explanatory and predictive properties of the quantum probability framework

Behavioral and Brain Sciences, 2013

An Empirical Test of Type-Indeterminacy in the Prisoner’s Dilemma

Lecture Notes in Computer Science, 2014

Strength and weight: The determinants of choice and confidence

Cognition, 2016