Document Type


Date of Degree Completion

Winter 2023

Degree Name

Master of Science (MS)


Primate Behavior

Committee Chair

Kara Gabriel

Second Committee Member

Mary Radeke

Third Committee Member

Sarah Sparks


Understanding cognition in small apes can provide insight into other primate and human cognitive capabilities because of their phylogenetic place between great apes and monkeys. Self-awareness or how an individual consciously knows and understands themselves is an important component of cognition, but previous research has yielded conflicting results regarding self-awareness in small apes. The current study utilized mirror self-recognition (MSR) procedures, a common test of self-awareness, that were modified to incorporate the social and behavioral ecology of small apes. A sample of six groups of gibbons and siamangs (Hylobatidae) housed at Wildlife World Zoo & Aquarium in Litchfield Park, AZ, were desensitized to their mirror image. Mirror-guided responses during desensitization and for a unique assortment of mirrors, food reward, and vocal stimuli, were observed and recorded using instantaneous scan sampling. Differences in responses were evaluated within-subjects across conditions. The findings support evidence that small apes engage in a variety of mirror-guided behaviors, some indicative of MSR and that desensitization is an important stage in the MSR procedure. Experimental phase (i.e., desensitization, mirror assortment, and food/vocal stimuli) significantly affected the occurrence of most behaviors, while there were individual differences in behavior during all phases. By modifying the mirror procedure to take species-specific ecological conditions into account, this study provides information on how to study self-awareness more effectively across species.

Available for download on Tuesday, March 07, 2028