The Impact of Degraded Speech and Stimulus Familiarity in a Dichotic Listening Task

It has been previously established that when engaged in a difficult attention intensive task, which involves repeating information while blocking out other information (the dichotic listening task), participants are often able to report hearing their own names in an unattended audio channel (Moray, 1959). This phenomenon, called the cocktail party effect is a result of words that are important to oneself having a lower threshold, resulting in less attention being necessary to process them (Treisman, 1960). The current studies examined the ability of a person who was engaged in an attention demanding task to hear and recall low-threshold words from a fictional story. These low-threshold words included a traditional alert word, "fire" and fictional character names from a popular franchise--Harry Potter. Further, the role of stimulus degradation was examined by including synthetic and accented speech in the task to determine how it would impact attention and performance. In Study 1 participants repeated passages from a novel that was largely unfamiliar to them, The Secret Garden while blocking out a passage from a much more familiar source, Harry Potter and the Deathly Hallows. Each unattended Harry Potter passage was edited so that it would include 4 names from the series, and the word "fire" twice. The type of speech present in the attended and unattended ears (Natural or Synthetic) was varied to examine the impact that processing a degraded speech would have on performance. The speech that the participant shadowed did not impact unattended recall, however it did impact shadowing accuracy. The speech type that was present in the unattended ear did impact the ability to recall low-threshold, Harry Potter information. When the unattended speech type was synthetic, significantly less Harry Potter information was recalled. Interestingly, while Harry Potter information was recalled by participants with both high and low Harry Potter experience, the traditional low-threshold word, "fire" was not noticed by participants. In order to determine if synthetic speech impeded the ability to report low-threshold Harry Potter names due to being degraded or simply being different than natural speech, Study 2 was designed. In Study 2 the attended (shadowed) speech was held constant as American Natural speech, and the unattended ear was manipulated. An accent which was different than the native accent of the participants was included as a mild form of degradation. There were four experimental stimuli which contained one of the following in the unattended ear: American Natural, British Natural, American Synthetic and British Synthetic. Overall, more unattended information was reported when the unattended channel was Natural than Synthetic. This implies that synthetic speech does take more working memory processing power than even an accented natural speech. Further, it was found that experience with the Harry Potter franchise played a role in the ability to report unattended Harry Potter information. Those who had high levels of Harry Potter experience, particularly with audiobooks, were able to process and report Harry Potter information from the unattended stimulus when it was British Natural. While, those with low Harry Potter experience were not able to report unattended Harry Potter information from this slightly degraded stimulus. Therefore, it is believed that the previous audiobook experience of those in the high Harry Potter experience group acted as training and resulted in less working memory being necessary to encode the unattended Harry Potter information. A pilot study was designed in order to examine the impact of story familiarity in the attended and unattended channels of a dichotic listening task. In the pilot study, participants shadowed a Harry Potter passage (familiar) in one condition with a passage from The Secret Garden (unfamiliar) playing in the unattended ear. A second condition had participants shadowing The Secret Garden (unfamiliar) with a passage from Harry Potter (familiar) present in the unattended ear. There was no significant difference in the number of unattended names recalled. Those with low Harry Potter experience reported significantly less attended information when they shadowed Harry Potter than when they shadowed The Secret Garden. Further, there appeared to be a trend such that those with high Harry Potter experience were reporting more attended information when they shadowed Harry Potter than The Secret Garden. This implies that experience with a franchise and characters may make it easier to recall information about a passage, while lack of experience provides no assistance. Overall, the results of the studies indicate that we do treat fictional characters in a way similarly to ourselves. Names and information about fictional characters were able to break through into attention during a task that required a great deal of attention. The experience one had with the characters also served to assist the working memory in processing the information in degraded circumstances. These results have important implications for training, design of alerts, and the use of popular media in the classroom.