The Deviation Effect

Research studies with young (18 to 30 years) and old adults (60 years and above; e.g., Röer et al., 2015) have found no difference between the two age groups on the deviation effect – the magnitude of disruption caused by sudden and unexpected changes in the irrelevant speech sequence which divert attention from the focal task to the irrelevant material. According to the duplex account, the deviation effect (unlike the CS effect) is amenable to top down control and therefore avoidable when such control is exerted to maintain attention on the focal task (e.g., Hughes, 2014, Hughes et al., 2013). Working memory capacity has long been assumed an indicator of attentional control and therefore it has followed that individuals who have a relatively higher working memory capacity (WMC) are better able to shield cognition from task-irrelevant stimuli much better than those with a lower capacity (Conway et al., 2001). Therefore, we may expect individuals with relatively low WMC to be more susceptible to the deviation effect than those with higher WMC (e.g., Hughes et al., 2013; Marsh, Vachon, & Sörqvist, 2017). This can also be extended to developmental differences wherein children who have lower WMC should be more susceptible to the deviation effect than higher WMC adults. It seems logical to expect a similar pattern for younger versus older adults whereby younger adults are less susceptible because of their larger WMC

compared to older people. However, evidence within the irrelevant sound paradigm suggests that there is an equivalence in the deviation effect for young and older adults even when task difficulty and intensity of sound is adjusted to individual ability (Bell & Buchner, 2007; Röer et al., 2015). The lack of a difference poses problems for the inhibitory deficit hypothesis which suggests that aging makes older adults less able to

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inhibit irrelevant stimuli because of the deficits in their attention and cognitive abilities (Hasher & Zacks, 1988; Lustig et al., 2007). This also raises questions about the differences that may emerge between children and adults given especially that

attentional control among this age group of children is still developing (e.g.: Cowan et al., 2006; Guttentag, 1997; Lane & Pearson, 1982) and their ability to exert top-down control in order to inhibit irrelevant information is less efficient than in adults (Hwang et al., 2010).

The results from individual analyses of children’s and adults’ data showed that while children experienced a deviation effect in all three tasks, the adults experienced this effect only in the missing-item task. The presence of a deviation effect across all three tasks for the children shows that attention was captured by deviants in the irrelevant sequence and lends support to the duplex account’s assertion that the

deviation effect is the result of attentional capture and is a task-insensitive and domain general type of distraction (Hughes et al., 2007). However, the absence of an effect of age on the magnitude of the deviation effect does not fall in line with predictions made by unitary and duplex accounts that children’s limited attentional control should have made them more susceptible to the deviation effect compared to adults. In addition, the absence of a deviation effect for two out of three tasks for the adults poses some difficulty for both accounts and stands in sharp contrast to several previous findings with adult participants that the deviation effect manifests regardless of task-type (e.g., Hughes et al., 2005, 2007; Vachon et al., 2016).

Nevertheless, an alternative explanation that focuses on task engagement may be more suited to the unusual pattern of results. Previous research has shown that when task engagement is encouraged by increasing perceptual difficulty of TBR stimuli, individuals are shielded from attentional capture (Hughes et al., 2013). Although the present study did not alter perceptual load, task engagement may have been promoted

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through the use of rehearsal. This would explain why, for adults, there was no deviation effect in the serial and probed recall tasks – tasks that rely on rehearsal – but a deviation effect was present in the missing-item task. The unique feature of the missing-item task is that participants have a priori knowledge of the list items and need to identify which item was left out of the list at presentation (Buschke, 1963). As such, serial order retention is not necessary and participants often engage in a mental ‘checking off’ strategy which allows them to eliminate presented items from the list of potential items and select the one that was missing (Beaman & Jones, 1997; Buschke, 1963; Murdock & Smith, 2005). In the present study, performance in the missing-item task in Quiet and all irrelevant speech conditions was better than that in serial and probed recall tasks. The use of serial rehearsal was not needed for this task (Beaman & Jones, 1997) and could imply that a lower level of attention and task engagement were needed to

complete the task. Therefore, the adults may have not benefitted from the shield against distraction otherwise provided by greater task engagement and higher cognitive load (Hughes et al., 2013; Marsh et al., 2016; Sörqvist et al., 2016).

In contrast to adults, the task engagement explanation could be applied as follows: children’s attempts to engage in rehearsal to support performance in serial and probed recall tasks may have acted as an attentional load rather than a shield, thus, leading to a deviation effect in these tasks (Elliott et al., 2016). The deviation effect in the missing-item task may be the result of poor attentional load alone that makes children more likely to have their attention captured by deviants. Furthermore, if children have poor attentional control then it should follow that they will be susceptible to attentional capture regardless of task type – as is the case here since the deviation effect was present for children in the missing-item task as well. Therefore, if greater task engagement imposes a further attentional load, it will exacerbate children’s

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contrast to adults for whom greater task engagement can act as a shield against attentional-based distraction (Hughes et al., 2013; Sörqvist, Dahlström, Karlsson, & Rönnberg, 2016). Given that children exhibited a deviation effect in more tasks than adults, it is surprising that no statistical effect of age was observed. However, the absence of an interaction with age could simply reflect that the magnitude of disruption was roughly the same for children and adults. In addition, the experimental design catered for each individual’s short-term memory capacity which may have suppressed developmental differences in the deviation effect. Following from this, in Study II, children aged five to eleven are included in the study to generalize findings across a wider age range of children; and, list length for recall is fixed to ensure similar levels of difficulty across participants.

In the present study, OSpan (Unsworth et al., 2005) was used to assess WMC and although adults had higher WMC than children, this did not result in an age-related difference in the magnitude of the deviation effect. The only relationship that was observed between WMC and the deviation effect was for adults in the probed recall task where higher WMC was associated with a lower deviation effect when deviants were in a steady-state sequence only. There was no relation between magnitude of disruption and WMC for children. The pattern of results among adults is similar to that in previous studies where individuals with high WMC were better able to resist attentional capture than those with low WMC (e.g., Hughes et al., 2013; Marsh et al., 2017; Sörqvist et al., 2013). Considering this previous evidence and the pattern seen here among adults, it is surprising that the magnitude of the deviation effect did not vary between adults and children even though WMC for adults was higher than that of the children. However, results from further analyses (in Section 2.3.5) indicated that the relation between WMC and the deviation effect may be more likely to occur among adults than children.

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more tasks than adults, it could be the case that developmental differences in distraction (at least between children and adults) are more likely to be qualitative than quantitative. In other words, even though the magnitude of the disruption did not vary as a function of age, children were still more susceptible to attentional capture by auditory distraction than adults (in line with findings from Elliott et al., 2016) as evidenced by the presence of the deviation effect for children in more tasks than adults.

2.4.4 Missing-item vs Probed Recall: The role of serial rehearsal