How memory of the past, a predictable present and expectations of the future underpin adaptation to the sound environment

Sammanfattning: By using auditory distraction as a tool, the main focus of the present thesis is to investigate the role of memory systems in human adaptation processes towards changes in the built environment. Report I and Report II focus on the question of whether memory for regularities in the auditory environment is used to form predictions and expectations of future sound events, and if violations of these expectations capture attention. Collectively the results indicate that once a stable neural model of the sound environment is created, violations of the formed expectations can capture attention. Furthermore, the magnitude of attentional capture is a function of the pitch difference between the expected tone and the presented tone.The second part of the thesis is concerned with, (a) the nature (i.e. the specificity) of the neural model formed in an auditory environment and, (b) whether complex cognition in terms of working memory capacity modulates habituation rate. The results in Report III show that the disruptive effect of the deviation effect diminishes with the number of exposures over time, and also as a function of working memory capacity. The aim of Report IV was to investigate the nature (and specificity) of the neural model formed in an auditory environment. If the neural model is fashioned around a specific stimulus then an observable increase of response latency should occur in conjunction with the deviant change. The results in Experiment 1 in Report IV, however, show that the habituation rate remained the same throughout the experiment. To further test the specificity of the neural model the modalityof the deviant event was switched (from auditory to visual and vice versa) in Experiment 3 in Report IV. The collective findings indicate that the formed neural model may be of a more general nature than previously suggested. The aim of Experiment 2 in Report IV was to investigate what properties of the sound environment underpin habituation rate, more specifically if predictability of a deviant trial facilitates the habituation process. The finding that the habituation rate was similar whether there was a fixed temporal interval between the deviant trials or a random interval suggests that the amount of occurrences (i.e. number of deviant trials) determines habituation rate, not the predictability of a deviant trial.