Type of Document Dissertation Author Gulledge, Jonathan Paul Author's Email Address jgulledge@leeuniversity.edu URN etd-04122006-165711 Title Hemispheric Differences in Numerical Cognition: A Comparative Investigation of How Primates Process Numerosity Degree Ph.D. Department Psychology Advisory Committee
Advisor Name Title David A. Washburn Committee Chair Claudio C. Cantalupo Committee Member Duane M. Rumbaugh Committee Member Eric J. Vanman Committee Member Keywords
- SNARC Effect
- Numeric Processing
- rTMS
- Transcranial Magnetic Stimulation
- Numerosity
- Numerical Cognition
Date of Defense 2006-04-12 Availability unrestricted Abstract ABSTRACT
Four experiments, using both humans and monkeys as participants, were conducted to investigate the similarities and differences in human and nonhuman primate numerical cognition. In Experiment 1 it was determined that both humans and monkeys display a SNARC effect, with similar symbolic distance effects for both species. In addition, both species were found to respond faster to congruent stimulus pairs. In Experiment 2 both species were found accurately to recognize quantitative stimuli when presented for durations of 150 msec in a divided visual field paradigm. Performance for humans and monkeys for numerals and dot-patterns was almost identical in terms of accuracy and response times. In Experiment 3 participants were required to make relative numerousness judgments in a divided visual field paradigm. Both species responded faster and more accurately to stimuli presented to the right visual field. Species differences appeared, with monkeys performing equally well on both trial types whereas the humans performed better on numeral trials than on dot trials. In Experiment 4 repetitive transcranial magnetic stimulation (rTMS) was combined with the divided visual field paradigm. Accuracy was significantly disrupted for both species when compared to a no stimulation condition. A facilitation effect was also evident with both species exhibiting significant decreases in response time for all trials. Right-handed participants took longer to respond to stimuli presented to the left visual field. These findings add to the body of knowledge regarding both the similarities and differences of how quantitative stimuli are processed by humans and monkeys.
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