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- Genre: Masters Thesis
Description
The current paper presents two studies that examine how asymmetries during interpersonal coordination are compensated for. It was predicted that destabilizing effects of asymmetries are stabilized through the recruitment and suppression of motor degrees-of-freedom (df). Experiment 1 examined this effect by having participants coordinate line movements of different orientations. Greater differences in asymmetries between participants yielded greater spatial deviation, resulting in the recruitment of df. Experiment 2 examined whether coordination of movements asymmetrical in shape (circle and line) yield simultaneous recruitment and suppression of df. This experiment also tested whether the initial stability of the performed movement alters the amount of change in df. Results showed that changes in df were exhibited as circles decreasing in circularity and lines increasing in circularity. Further, more changes in df were found circular (suppression) compared to line (recruitment) movements.
ContributorsFine, Justin (Author) / Amazeen, Eric L (Thesis advisor) / Amazeen, Polemnia G (Committee member) / Brewer, Gene A. (Committee member) / Arizona State University (Publisher)
Created2013
Description
This study explores the psychophysical and neural processes associated with the perception of sounds as either pleasant or aversive. The underlying psychophysical theory is based on auditory scene analysis, the process through which listeners parse auditory signals into individual acoustic sources. The first experiment tests and confirms that a self-rated pleasantness continuum reliably exists for 20 various stimuli (r = .48). In addition, the pleasantness continuum correlated with the physical acoustic characteristics of consonance/dissonance (r = .78), which can facilitate auditory parsing processes. The second experiment uses an fMRI block design to test blood oxygen level dependent (BOLD) changes elicited by a subset of 5 exemplar stimuli chosen from Experiment 1 that are evenly distributed over the pleasantness continuum. Specifically, it tests and confirms that the pleasantness continuum produces systematic changes in brain activity for unpleasant acoustic stimuli beyond what occurs with pleasant auditory stimuli. Results revealed that the combination of two positively and two negatively valenced experimental sounds compared to one neutral baseline control elicited BOLD increases in the primary auditory cortex, specifically the bilateral superior temporal gyrus, and left dorsomedial prefrontal cortex; the latter being consistent with a frontal decision-making process common in identification tasks. The negatively-valenced stimuli yielded additional BOLD increases in the left insula, which typically indicates processing of visceral emotions. The positively-valenced stimuli did not yield any significant BOLD activation, consistent with consonant, harmonic stimuli being the prototypical acoustic pattern of auditory objects that is optimal for auditory scene analysis. Both the psychophysical findings of Experiment 1 and the neural processing findings of Experiment 2 support that consonance is an important dimension of sound that is processed in a manner that aids auditory parsing and functional representation of acoustic objects and was found to be a principal feature of pleasing auditory stimuli.
ContributorsPatten, Kristopher Jakob (Author) / Mcbeath, Michael K (Thesis advisor) / Baxter, Leslie C (Committee member) / Amazeen, Eric L (Committee member) / Dorman, Michael F. (Committee member) / Arizona State University (Publisher)
Created2014
Description
Perceived heaviness of lifted objects has been shown to scale to a ratio of muscle activity and movement during elbow lifts. This scaling reflects the importance of the forces applied to an object and the resulting kinematics for this perception. The current study determined whether these perceived heaviness dynamics are similar in other lifting conditions. Anatomically sourced context-conditioned variability has implications for motor control. The current study investigated whether these implications also hold for heaviness perception. In two experiments participants lifted objects with knee extension lifts and with several arm lifts and reported perceived heaviness. The resulting psychophysiological functions revealed the hypothesized muscle activity and movement ratio in both leg and arms lifts. Further, principal component regressions showed that the forearm flexors and corresponding joint angular accelerations were most relevant for perceived heaviness during arm lifts. Perceived heaviness dynamics are similar in the arms and legs.
ContributorsWaddell, Morgan (Author) / Amazeen, Eric L (Thesis advisor) / Amazeen, Polemnia G (Committee member) / Brewer, Gene A. (Committee member) / Arizona State University (Publisher)
Created2016
Description
Fractal analyses examine variability in a time series to look for temporal structure
or pattern that reveals the underlying processes of a complex system. Although fractal
property has been found in many signals in biological systems, how it relates to
behavioral performance and what it implies about the complex system under scrutiny are
still open questions. In this series of experiments, fractal property, movement kinematics,
and behavioral performance were measured on participants performing a reciprocal
tapping task. In Experiment 1, the results indicated that the alpha value from detrended
fluctuation analysis (DFA) reflected deteriorating performance when visual feedback
delay was introduced into the reciprocal tapping task. This finding suggests that this
fractal index is sensitive to performance level in a movement task. In Experiment 2, the
sensitivity of DFA alpha to the coupling strength between sub-processes within a system
was examined by manipulation of task space visibility. The results showed that DFA
alpha was not influenced by disruption of subsystems coupling strength. In Experiment 3,
the sensitivity of DFA alpha to the level of adaptivity in a system under constraints was
examined. Manipulation of the level of adaptivity was not successful, leading to
inconclusive results to this question.
or pattern that reveals the underlying processes of a complex system. Although fractal
property has been found in many signals in biological systems, how it relates to
behavioral performance and what it implies about the complex system under scrutiny are
still open questions. In this series of experiments, fractal property, movement kinematics,
and behavioral performance were measured on participants performing a reciprocal
tapping task. In Experiment 1, the results indicated that the alpha value from detrended
fluctuation analysis (DFA) reflected deteriorating performance when visual feedback
delay was introduced into the reciprocal tapping task. This finding suggests that this
fractal index is sensitive to performance level in a movement task. In Experiment 2, the
sensitivity of DFA alpha to the coupling strength between sub-processes within a system
was examined by manipulation of task space visibility. The results showed that DFA
alpha was not influenced by disruption of subsystems coupling strength. In Experiment 3,
the sensitivity of DFA alpha to the level of adaptivity in a system under constraints was
examined. Manipulation of the level of adaptivity was not successful, leading to
inconclusive results to this question.
ContributorsNguyen, Tri, M.A (Author) / Amazeen, Eric L (Thesis advisor) / Glenberg, Arthur M. (Thesis advisor) / Amazeen, Polemnia G (Committee member) / Arizona State University (Publisher)
Created2019