Abstract
Lacey’s (1959) intake-rejection hypothesis described the differentiation of physiological responses during internally directed attention (IDA) and externally directed attention (EDA). Previously, very little research which considers both autonomic nervous system (ANS) and central nervous system (CNS) correlates in relation to the original Lacey’s hypothesis has been carried out (e.g. Cooper et al., 2003; Cooper et al., 2006). Furthermore, various issues regarding the incomparable EDA and IDA tasks used from one study to another in previous research have yet to be addressed. Additionally, individual differences in EDA and IDA task completion and performance were investigated in previous studies (i.e. Ziegler et al., 2018). When presented with choices (e.g. providing a correct response), individuals with different personalities respond differently to EDA and IDA tasks (Allan et al., 2015; Berkman et al., 2019; Lerman et al., 2010). This could introduce confounding factors that contributed to the findings.To address the gaps and differences in previous research noted above, three studies were conducted to investigate EDA-IDA differentiation from the perspective of ANS, CNS and behavioural indices. To investigate this, Study 1 and Study 2 focused on visual and auditory modalities, respectively. The tasks used were an improvement on those used in previous studies as they were controlled for (i) intentionality of information processing, (ii) thinking style and (iii) other stimuli factors that could confound the findings observed (i.e. task modality and non-spatial features of stimuli). Moreover, ANS indices (heart rate and respiration sinus arrhythmia) and CNS indices (EEG power and coherence) were also measured to compare CNS correlates to the ANS correlates observed in Lacey’s hypothesis.
Finally, in Study 3, individual differences in EDA and IDA processing were measured using signal detection theory (SDT).
There was no difference in heart rate between EDA and IDA, but a longer respiratory sinus arrhythmia (RSA) was observed during EDA and a shorter RSA during IDA, suggesting it might be a more subtle index of ANS fluctuation during EDA/IDA. Theta event-related synchronisation (ERS) observed in the midfrontal region across visual and auditory modality was found to be linked to sustained attention. Additionally, theta ERS in the posterior region for visual modality was associated with visual processing. Parietooccipital beta ERS observed at the posterior region for visual modality, was linked to active attention and movement inhibition. Moreover, frontal alpha ERS during EDA and event-related desynchronisation (ERD) during IDA, observed in the visual modality, were associated with attentional demands. Scalp wide alpha ERS, on the other hand, was associated with the inhibition timing hypothesis. A general beta ERS (not ROI specific) during both auditory EDA and IDA can be attributed to active attention. Further exploratory EEG analysis (i.e. absolute power change) revealed similar patterns for EDA and IDA across theta, alpha, and beta frequencies. In the visual modality, both EDA and IDA produced an increase in amplitude (relative to the prestimulus condition) for theta, alpha and beta frequencies. In contrast, within the auditory modality, a decrease in amplitude during EDA and IDA (relative to the prestimulus condition) was observed in the theta and alpha frequencies, but an increase was observed in the beta frequencies. In Study 3, response bias was observed for Behavioural Inhibition System scorers during the EDA condition, suggesting that personality traits might influence the processing of EDA and IDA tasks. Overall, the findings provided evidence of modality- independent and modality-dependent characteristics of EDA and IDA. Furthermore, individual differences also appear to influence the cognitive processing of EDA and IDA.
| Date of Award | 9 Dec 2024 |
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| Original language | English |
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| Supervisor | Roger Moore (Supervisor), Darren Van Laar (Supervisor) & Nicholas J. Cooper (Supervisor) |