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- Creators: Santello, Marco
Description
Existing theories suggest that evidence is accumulated before making a decision with competing goals. In motor tasks, reward and motor costs have been shown to influence the decision, but the interaction between these two variables has not been studied in depth. A novel reward-based sensorimotor decision-making task was developed to investigate how reward and motor costs interact to influence decisions. In human subjects, two targets of varying size and reward were presented. After a series of three tones, subjects initiated a movement as one of the targets disappeared. Reward was awarded when participants reached through the remaining target within a specific amount of time. Subjects had to initiate a movement before they knew which target remained. Reward was found to be the only factor that influenced the initial reach. When reward was increased, there was a lower probability of intermediate movements. Both target size and reward lowered reaction times individually and jointly. This interaction can be interpreted as the effect of the expected value, which suggests that reward and target size are not evaluated independently during motor planning. Curvature, or the changing of motor plans, was driven primarily by the target size. After an initial decision was made, the motor costs to switch plans and hit the target had the largest impact on the curvature. An interaction between the reward and target size was also found for curvature, suggesting that the expected value of the target influences the changing of motor plans. Reward, target size, and the interaction between the two were all significant factors for different parts of the decision-making process.
ContributorsBoege, Scott (Author) / Santello, Marco (Thesis advisor) / Fine, Justin (Committee member) / McClure, Samuel (Committee member) / Buneo, Christopher (Committee member) / Arizona State University (Publisher)
Created2019
Description
Understanding human-human interactions during the performance of joint motor tasks is critical for developing rehabilitation robots that could aid therapists in providing effective treatments for motor problems. However, there is a lack of understanding of strategies (cooperative or competitive) adopted by humans when interacting with other individuals. Previous studies have investigated the cues (auditory, visual and haptic) that support these interactions but understanding how these unconscious interactions happen even without those cues is yet to be explained. To address this issue, in this study, a paradigm that tests the parallel efforts of pairs of individuals (dyads) to complete a jointly performed virtual reaching task, without any auditory or visual information exchange was employed. Motion was tracked with a NDI OptoTrak 3D motion tracking system that captured each subject’s movement kinematics, through which we could measure the level of synchronization between two subjects in space and time. For the spatial analyses, the movement amplitudes and direction errors at peak velocities and at endpoints were analyzed. Significant differences in the movement amplitudes were found for subjects in 4 out of 6 dyads which were expected due to the lack of feedback between the subjects. Interestingly, subjects in this study also planned their movements in different directions in order to counteract the visuomotor rotation offered in the test blocks, which suggests the difference in strategies for the subjects in each dyad. Also, the level of de-adaptation in the control blocks in which no visuomotor rotation was offered to the subjects was measured. To further validate the results obtained through spatial analyses, a temporal analyses was done in which the movement times for the two subjects were compared. With the help of these results, numerous interaction scenarios that are possible in the human joint actions in without feedback were analyzed.
ContributorsAgrawal, Ankit (Author) / Buneo, Christopher (Thesis advisor) / Santello, Marco (Committee member) / Tillery, Stephen Helms (Committee member) / Arizona State University (Publisher)
Created2016
Description
Loss aversion manifests as a decision bias in which avoiding losses is preferred over acquiring rewards and can drastically alter an individual’s decision-making by overweighting potential losses relative to gains of equal magnitude. Consequently, individuals may require greater positive compensation to offset potential losses, exhibit contradictory choice preferences, or even avoid the decision entirely; and this behavior may be ascribed to an over-reliance on automatic, unconscious (intuitive) judgments rather than initiating analytic reasoning more capable of objectively evaluating outcomes.
Religion (specifically Christianity) is the topic of focus, as preliminary evidence suggests an individual’s intuitive inclinations positively correlate with and predict religious beliefs. Moreover, self-reported religious beliefs significantly differed as a function of inducing either intuitive or reflective mindsets. Therefore, the purpose of this experiment was to test the hypothesis that religious participants will display significantly greater levels of loss aversion than nonreligious participants.
This hypothesis extends from a previous study relating large-scale cultural and religious differences with loss aversion. While their results revealed religious orthodoxy strongly influenced loss aversion, the parameters elicited may be less stable as only two lottery questions were asked and religion was determined by cultural demographics. This study used the same design, but with a total of ten lotteries and a more detailed investigation into individual religious factors.
While loss aversion coefficients replicated the overall behavioral effect (Median θ = 2.6), independent sample, Mann-Whitney U tests did not yield any significant differences between Christian and Nonreligious participants (p > 0.05); nor did any of the religious factors examined account for a significant amount of variability.
This study attempted to add to current knowledge by further conflating the relationship between religiosity and adaptive decision strategies susceptible to errant and inconsistent behavior. While the hypotheses were unsupported, a null finding is still important, and future research re-testing this association or introducing causational designs may prove more fruitful in understanding these complex relationships.
Religion (specifically Christianity) is the topic of focus, as preliminary evidence suggests an individual’s intuitive inclinations positively correlate with and predict religious beliefs. Moreover, self-reported religious beliefs significantly differed as a function of inducing either intuitive or reflective mindsets. Therefore, the purpose of this experiment was to test the hypothesis that religious participants will display significantly greater levels of loss aversion than nonreligious participants.
This hypothesis extends from a previous study relating large-scale cultural and religious differences with loss aversion. While their results revealed religious orthodoxy strongly influenced loss aversion, the parameters elicited may be less stable as only two lottery questions were asked and religion was determined by cultural demographics. This study used the same design, but with a total of ten lotteries and a more detailed investigation into individual religious factors.
While loss aversion coefficients replicated the overall behavioral effect (Median θ = 2.6), independent sample, Mann-Whitney U tests did not yield any significant differences between Christian and Nonreligious participants (p > 0.05); nor did any of the religious factors examined account for a significant amount of variability.
This study attempted to add to current knowledge by further conflating the relationship between religiosity and adaptive decision strategies susceptible to errant and inconsistent behavior. While the hypotheses were unsupported, a null finding is still important, and future research re-testing this association or introducing causational designs may prove more fruitful in understanding these complex relationships.
ContributorsHowatt, Brian (Author) / Robles-Sotelo, Elias (Thesis advisor) / Vargas, Perla (Committee member) / Neal, Tess (Committee member) / Arizona State University (Publisher)
Created2017