Subjective experience and the attentional lapse: task engagement and disengagement during sustained attention.

Three experiments investigated the relationship between subjective experience and attentional lapses during sustained attention. These experiments employed two measures of subjective experience (thought probes and questionnaires) to examine how differences in awareness correspond to variations in both task performance (reaction time and errors) and psycho-physiological measures (heart rate and galvanic skin response). This series of experiments examine these phenomena during the Sustained Attention to Response Task (SART, Robertson, Manly, Adrade, Baddeley, & Yiend, 1997). The results suggest we can dissociate between two components of subjective experience during sustained attention: (A) task unrelated thought which corresponds to an absent minded disengagement from the task and (B) a pre-occupation with one's task performance that seems to be best conceptualised as a strategic attempt to deploy attentional resources in response to a perception of environmental demands which exceed ones ability to perform the task. The implications of these findings for our understanding of how awareness is maintained on task relevant material during periods of sustained attention are discussed.

The consequences of encoding information on the maintenance of internally generated images and thoughts: the role of meaning complexes.

Three experiments investigated the hypothesis that internally generated images and thoughts were driven by meaning complexes, a construct which reflects a synthesis of semantic meaning and personal salience (Klinger, 1999). Experiments 1 and 2 contrasted the mutual inhibition between encoding words and non-words on: (i) the frequency that thoughts and images unrelated to the task (task unrelated thought, TUT) were experienced (Experiment 1) and (ii) on the intensity of images generated from long-term memory and maintained under dual task conditions, which whilst familiar were not of particular personal salience (Experiment 2). Experiment 3 examined the physiological arousal associated with the experience of TUT in a semantic encoding task. Evidence suggested that, in general, internally generated images and thoughts, irrespective of the personal salience, were suppressed by the co-ordination of information in working memory. In addition, only the experience of spontaneous images and thoughts of personal salience (TUT, Experiments 1 and 3) interfered reliably with the encoding/retrieval of semantic information from memory. Finally, in Experiment 3, physiological arousal, as indexed by mean heart rate, was associated with a high frequency of TUT. The results of all three experiments support the notion that the maintenance of spontaneously occurring images and thoughts is simultaneously influenced by both the semantic content and the personal salience of the information held in working memory.