The influence of expectation and experience on auditory perception

Thesis

Listeners exploit statistical regularities in the environment to guide auditory attention. This thesis investigates how expectations based on stimulus frequency and spatial location influence auditory perception across species and tasks. The first two chapters focus on the probe signal effect, using paradigms in which frequency is orthogonal to the task. Humans and ferrets completed a tone-in-noise detection task, while a separate duration discrimination task was conducted in ferrets. Both tasks manipulated the probability of target frequencies. The results show that whether expected or unexpected frequencies are prioritised varies by species and task design. In some conditions, ferrets showed improved performance for low-probability probe tones, consistent with deviance detection, while in others they showed higher accuracy for expected tones. Some human results diverged from previous findings using two-alternative forced-choice designs, suggesting that task structure can shape attentional biases. Together, these findings indicate that frequency-based expectations influence behaviour, but that this influence is not uniform across tasks or species.

The third chapter examines spatial attention in mice using a vertical oddball paradigm combined with pupillometry and ear tracking. In addition to deviance detection, mice showed greater pupil dilations for sounds from above, suggesting a threat detection mechanism that was still present after pinnae removal. A subsequent go/no-go task showed that mice, contrary to popular belief, have strong vertical localisation abilities. After altering spectral cues by pinnae manipulation, mice could quickly relearn localisation to the level before manipulation.

Overall, the results demonstrate that expectations guide auditory attention in both frequency and spatial domains, but that the form and direction of this bias depend on species, task demands, and stimulus context. Together, these behavioural paradigms establish a foundation for future physiological investigations into neural mechanisms of statistics-driven and spatial auditory attention across species.

Authors: Bochtler, K

• DOI: 10.5287/ora-8jegmq1kg
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: probe signal effect; statistical learning; expectation; pupillometry; auditory attention; deviance detection; cross-species comparison; sound localisation
• Subjects: Neurosciences