The aim of the work reported in this thesis is to investigate a methodology for studying perception by building and testing robotic models of animal sensory mechanisms. Much of Artificial Intelligence studies agent perception by exploring architectures for linking (often abstract) sensors and motors so as to give rise to particular behaviour. By contrast, this work proposes that perceptual investigations should begin with a characterisation of the underlying physical laws which govern the specific interaction of a sensor (or actuator) with its environment throughout the execution of a task. Moreover, it demonstrates that, through an understanding of task-physics, problems for which architectural solutions or explanations are often proposed may be solved more simply at the sensory interface - thereby minimising subsequent computation. This approach is applied to an investigation of the acoustical cues that may be exploited by several species of tone emitting insectivorous bats (species in the families Rhinolophidae and Hipposideridae) which localise prey using systematic pinnae scanning movements. From consideration of aspects of the sound filtering performed by the external and inner ear or these bats, three target localisation mechanisms are hypothesised and tested aboard a 6 degree-of-freedom, binaural, robotic echolocation system. In the first case, it is supposed that echolocators with narrow-band call structures use pinna movement to alter the directional sensitivity of their perceptual systems in the same whay that broad-band emitting bats rely on pinnae morphology to alter acoustic directionality at different frequencies. Scanning receivers also create dynamic cues - in the form of frequency and amplitude modulations - which very systematically with target angle. The second hypothesis investigated involves the extraction of timing cues from amplitude modulated echo envelopes.

Thesis (MPH)--University of Limpopo, 2010. / Background Virginity testing is a practice that has stimulated lots of discussions amongst people from various perspectives. Controversies around this practice have necessitated further research in order to bring the voice of girls into the virginity testing debate. Aim and objective The aim of the study was to explore perceptions and experiences of girls on the practice of virginity testing. Methodology Triangulation of qualitative data collective method was used. The researcher informally engaged in key informants’ interviews with stakeholders who participate in the practice attended virginity testing celebration to observe the proceedings and processes conducted during the practice. Focus group discussions were conducted. Data was analyzed using NVIVO. Results Elders, in particular mothers, encouraged participation of girls in virginity testing. Girls observed and sighted benefits, ranging from viz: HIV/STI prevention, societal recognition and acceptance, purity before marriage and delay of sexual debut. Non participation was attributed to the in availability of virginity testing practices the areas. Concerns of doggy behaviors by testers, uneducated testers of testers, compromised health standards were discussed. Conclusions These findings reveal that there are areas of misunderstanding on how the practice is viewed and represented in the media. Arguments against virginity testing seem to be based on the perspective of on Westernized, feminist and individualistic notions of humanity disregarding the social construction of traditional cultural practices. Socialization and moral standards of people from a particularly Western orientation dominate the debate against virginity testing with no basis that is supported by research.

Speech perception is challenging because the acoustic input is extremely variable. This variability partially stems from differences in how talkers pronounce words. For example, Voice Onset Time (VOT) is the primary cue that distinguishes /b/ from /p/. Women tend to use longer Voice Onset Times (VOTs) than men. A VOT of 20 msec could thus be a /b/ spoken by a woman and a /p/ spoken by a man. A critical question is how listeners deal with this variability. Previous research shows that listeners use these regularities (e.g., the systematic relationship between gender and VOT) to compensate for variability. For example, listeners adjust their phoneme category boundary based on talker gender. However, it is unclear the exact mechanisms by which talker gender information influences speech processing. Talker gender could influence only later stages of speech processing, like phoneme categorization. Alternatively, talker gender could modulate the earliest stage: acoustic cue encoding. I use event-related potentials, eye-tracking in the visual world paradigm, and electrocorticography to isolate the specific role of talker gender in speech perception. The results show that the auditory system influences the earliest stage of speech perception by allowing cues to be encoded relative to prior expectations about gender and that gender is integrated with acoustic cues during lexical activation. These experiments give insight into how the brain deals effectively with variability during categorization.

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