Matching Items (6)

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How does rate influence brain activity during drumming in persons with Down Syndrome?

Description

Persons with Down Syndrome (DS) have been repeatedly shown to have timing deficits, to move slowly, and to not follow metronomes. This timing deficit in persons with DS requires further study because timing is fundamental to movement control. Furthermore, brain

Persons with Down Syndrome (DS) have been repeatedly shown to have timing deficits, to move slowly, and to not follow metronomes. This timing deficit in persons with DS requires further study because timing is fundamental to movement control. Furthermore, brain imaging studies have proposed a rate effect in which increased cortical activation in the primary motor cortex was observed during increased finger movement frequency. The aim of the current study was to determine if the rate effect was present in persons with DS by comparing brain activation in self-selected and as fast as possible rates. Eight participants with DS performed unimanual drumming at their self-selected and maximal rates. Movement rate was measured at EEG was collected in the alpha (8-12 Hz) and Beta (13-30 Hz) frequencies from C3 and C4. The results showed that overall, their self-selected rates were slower than their maximal rates, indicating that they are capable of modifying their movement rate with general instructions. Furthermore, there were significant differences in Beta in which there was more activation during as fast as possible than self-selected tapping in both sides of the primary motor cortex in persons with DS. This suggests that their brains are activated in a similar manner as the typical population with respect to movement rate. Overall, our results suggest that while interventions that involve timing to specific rates are difficult, people with DS can perform at self-selected and maximal rates. The results of our study show that they can alter movement rate when provided with general instruction or additional motivation.

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Agent

Created

Date Created
2013-05

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Baseball's Sight-Audition Farness Effect (Safe) when umpiring baserunners: competing visual and auditory cues

Description

In baseball, the difference between a win and loss can come down to a single call, such as when an umpire judges force outs at first base by typically comparing competing auditory and visual inputs of the ball-mitt sound and

In baseball, the difference between a win and loss can come down to a single call, such as when an umpire judges force outs at first base by typically comparing competing auditory and visual inputs of the ball-mitt sound and the foot-on-base sight. Yet, because the speed of sound in air only travels about 1100 feet per second, fans observing from several hundred feet away will receive auditory cues that are delayed a significant portion of a second, and thus conceivably could systematically differ in judgments compared to the nearby umpire. The current research examines two questions. 1. How reliably and with what biases do observers judge the order of visual versus auditory events? 2. Do observers making such order judgments from far away systematically compensate for delays due to the slow speed of sound? It is hypothesized that if any temporal bias occurs it is in the direction consistent with observers not accounting for the sound delay, such that increasing viewing distance will increase the bias to assume the sound occurred later. It was found that nearby observers are relatively accurate at judging if a sound occurred before or after a simple visual event (a flash), but exhibit a systematic bias to favor visual stimuli occurring first (by about 30 msec). In contrast, distant observers did not compensate for the delay of the speed of sound such that they systematically favored the visual cue occurring earlier as a function of viewing distance. When observers judged simple visual stimuli in motion relative to the same sound burst, the distance effect occurred as a function of the visual clarity of the ball arriving. In the baseball setting, using a large screen projection of baserunner, a diminished distance effect occurred due to the additional visual cues. In summary, observers generally do not account for the delay of sound due to distance.

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Agent

Created

Date Created
2017

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Temporal Color Perception

Description

Color perception has been widely studied and well modeled with respect to combining visible electromagnetic frequencies, yet new technology provides the means to better explore and test novel temporal frequency characteristics of color perception. Experiment 1 tests how reliably participants

Color perception has been widely studied and well modeled with respect to combining visible electromagnetic frequencies, yet new technology provides the means to better explore and test novel temporal frequency characteristics of color perception. Experiment 1 tests how reliably participants categorize static spectral rainbow colors, which can be a useful tool for efficiently identifying those with functional dichromacy, trichromacy, and tetrachromacy. The findings confirm that all individuals discern the four principal opponent process colors, red, yellow, green, and blue, with normal and potential tetrachromats seeing more distinct colors than color blind individuals. Experiment 2 tests the moving flicker fusion rate of the central electromagnetic frequencies within each color category found in Experiment 1 as a test of the Where system. It then compares this to the maximum temporal processing rate for discriminating direction of hue change with colors displayed serially as a test of the What system. The findings confirm respective processing thresholds of about 20 Hz for Where and 2-7 Hz for What processing systems. Experiment 3 tests conditions that optimize false colors based on the spinning Benham’s Top illusion. Findings indicate the same four principal colors emerge as in Experiment 1, but at low saturation levels for trichromats that diminish further for dichromats. Taken together, the three experiments provide an overview of the common categorical boundaries and temporal processing limits of human color vision.

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Agent

Created

Date Created
2021

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The Effects of Differential Exposure to Gruesome Photographs on Mock Jurors' Emotions & Legal Judgments

Description

In a trial, jurors are asked to set aside their emotions and make judgments based solely on evidence. Research suggests jurors are not always capable of this, particularly when exposed to gruesome photographic evidence. However, previous research has not looked

In a trial, jurors are asked to set aside their emotions and make judgments based solely on evidence. Research suggests jurors are not always capable of this, particularly when exposed to gruesome photographic evidence. However, previous research has not looked at the potentially moderating effect of when and for how long jurors are exposed to emotionally disturbing photographs, nor how many photographs they see. In two experiments I tested the impact of the timing of and extent of exposure to gruesome photographs on jurors’ emotions, verdicts, and punishment recommendations. In Study 1, I investigated the effect of timing and exposure duration to a single gruesome photograph of a victim in a murder case (no exposure, brief early exposure, brief late exposure, and prolonged exposure) on mock jurors’ emotions and case judgments. Prolonged exposure (relative to no or brief exposure, regardless of timing) increased disgust, which in turn was associated with harsher punishment. Contrary to previous research, the photograph manipulation did not influence verdicts. The results were mixed and inconclusive regarding brief early versus late exposure. In Study 2, I compared repeatedly viewing a single gruesome photograph to viewing a set of four similar, but unique gruesome photographs—holding the exposure time constant—to assess the impact of quantity of photos on jurors’ emotions and case judgments. Viewing multiple gruesome photos (relative to no photos) led to increase in guilty verdicts through increased disgust, replicating previous research. Viewing a single gruesome photo (relative to no photo) led to increase in guilty verdicts through disgust, differing from Study 1 findings. Viewing multiple gruesome photos and a single gruesome photo led to more disgust, compared to viewing no photo. However, differing from Study 1, gruesome photographs did not lead to an increase in punishment recommendations. There were no significant differences between exposure to a single or multiple gruesome photos on disgust, verdicts, or punishments. Overall, greater exposure to gruesome evidence led to increased disgust and punitiveness, relative to those with less exposure. However, jurors with greater exposure to the same or different photographs did not differ in reported emotions, verdicts, or punitiveness.

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Created

Date Created
2020

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Interval timing under a behavioral microscope: dissociating motivational and timing processes in fixed-interval performance

Description

Theories of interval timing have largely focused on accounting for the aggregate properties of behavior engendered by periodic reinforcement, such as sigmoidal psychophysical functions and their scalar property. Many theories of timing also stipulate that timing and motivation are inseparable

Theories of interval timing have largely focused on accounting for the aggregate properties of behavior engendered by periodic reinforcement, such as sigmoidal psychophysical functions and their scalar property. Many theories of timing also stipulate that timing and motivation are inseparable processes. Such a claim is challenged by fluctuations in and out of states of schedule control, making it unclear whether motivation directly affects states related to timing. The present paper seeks to advance our understanding of timing performance by analyzing and comparing the distribution of latencies and inter-response times (IRTs) of rats in two fixed-interval (FI) schedules of food reinforcement (FI 30-s and FI 90-s), and in two levels of food deprivation. Computational modeling revealed that each component was well described by mixture probability distributions embodying two-state Markov chains. Analysis of these models revealed that only a subset of latencies are sensitive to the periodicity of reinforcement, and pre-feeding only reduces the size of this subset. The distribution of IRTs suggests that behavior in FI schedules is organized in bouts that lengthen and ramp up in frequency with proximity to reinforcement. Pre-feeding slowed down the lengthening of bouts and increased the time between bouts. When concatenated, these models adequately reproduced sigmoidal FI response functions. These findings suggest that behavior in FI fluctuates in and out of schedule control; an account of such fluctuation suggests that timing and motivation are dissociable components of FI performance. These mixture-distribution models also provide novel insights on the motivational, associative, and timing processes expressed in FI performance, which need to be accounted for by causal theories of interval timing.

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Agent

Created

Date Created
2015

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Hippocampal Contributions to the Temporal Dynamics of Behavior

Description

The capacity to track time in the seconds-to-minutes range, or interval timing, appears to be at least partially dependent on intact hippocampal (HPC) function. The current dissertation sought to dissociate timed responses, non-timed responses, and motivational aspects of behavior in

The capacity to track time in the seconds-to-minutes range, or interval timing, appears to be at least partially dependent on intact hippocampal (HPC) function. The current dissertation sought to dissociate timed responses, non-timed responses, and motivational aspects of behavior in order to propose a role of the HPC in specific timing sub-processes. In Chapter 2, effects of dorsal HPC (dHPC) lesions on temporal responding in a switch-timing task revealed a critical role of dHPC in the acquisition of interval timing criteria. Following dHPC lesions, the start time of responding was systemically shortened, in a manner that was enhanced and sustained when encoding a novel long interval, consistent with a memory-based account of dHPC function in timed responding. Chapter 3 investigated effects of chronic stress, which has been shown to reliably induce HPC dendritic retraction, on interval timing, utilizing response-initiated schedules of reinforcement, which facilitate deconvolution of timing and motivation. This revealed task-dependent effects on interval timing and motivation, where stress induced transient effects on motivation in a prospective timing task, but transient effects on the variability of timed responding in a retrospective timing task, consistent with an effect on memory function in interval timing. Chapter 4 sought to bring timed responding, motivation, and non-timed behaviors under stronger procedural control, through the implementation of a response-initiated timing-with-opportunity-cost task, in which a cost is imposed on temporal food-seeking by the presence of a concurrent source of probabilistic reinforcement. This arrangement garnered strong schedule control of behavior, and revealed individual-subject differences in the effects of reward devaluation, such that it affected motivation in some rats, but temporal responding in others. Using this methodology, Chapter 5 investigated initial temporal entrainment of behavior under pharmacological deactivation of dHPC and revealed its critical involvement in updating memory to new temporal contingencies. Together, data from this dissertation contrast with prior conclusions that the HPC is not involved in learning temporal criteria, and instead suggest that its function is indeed critical to encoding temporal intervals in memory.

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Agent

Created

Date Created
2022