2.3.1 The Use of Interference
Based upon the work of Vergauwe et al. (2009) in attempting to differentiate visual and spatial interference impact, and that of Allen et al. (2014), the current doctoral thesis will employ a dual task methodology to investigate the type of representation use of the quantitative and qualitative change detection tasks. The visuospatial Bar Fit task will be taken from the work of Vergauwe et al. (2009) to assess the impact of visuospatial interference on both types of change detection tasks. During this task, participants have to respond has to respond to a series of three items as whether a bar could pass through a gap between two dots. Vergauwe et al. (2009) proposed that this task requires the use of visuospatial
43 attentional resources as it was demonstrated that the Bar Fit task could interfere with both visual and spatial working memory protocols.
As one of the main aims of the current thesis is to look at the domain specific versus the multicomponent nature of two change detection tasks, a verbal attentional interference protocol will be added to look at the use of the verbal components of the working memory architecture. Lépine, Bernardin and Barrouillet (2005) introduced a verbal interference protocol known as a Verbal Parity Task. Within this task, participants are verbally presented with a series of three numbers and after each number is presented, a keyboard response is made deciding whether the number is odd or even in nature. Lépine et al. (2005) proposed that this task specifically used the Phonological Loop component within the working memory architecture, however it was also suggested that this task could be detrimental to memory due to the ability to encourage participants to divide attentional control between a primary and secondary task.
The use of a dual task methodology can assist in providing evidence towards either a multicomponent or domain approach to the attentional/semantic representation use of these tasks. If the Bar Fit Task only causes interference effects then a domain specific approach can be adopted (Baddeley, 2012). If verbal interference effects are present then this can raise question with regards to the multicomponent approaches to visual working memory (Logie, 2011).
2.3.2 The Use of ERP
An alternative methodology to differentiate the modality specific versus modality general architecture is based upon the work of Riby and Orme (2013). Riby and Orme investigated the working memory architecture of a variation of the Visual Patterns Test by using electrophysiological recordings to do so. Three specifically chosen ERP components were
44 used in the experiment. The N400 ERP component was chosen as this had been shown to have a heightened activation if the use of semantics were present during the encoding of faces (Eimer, 2000) and non-visual word stimuli (Kutas and Federmeier, 2011; Kiefer, 2002). The N200 ERP component was used as a marker of early visual processing and it was proposed that this component was activated when more complex visual stimuli was presented (Berti, Geissler, Lachmann and Mecklinger, 2000). Morgan, Jackson, Klein, Mohr, Shapiro and Linden (2010) had proposed that the N200 was colour visual specific, prompting the current researchers to also use this ERP component. Finally, as a marker of attentional control, the P300 was used. Riby and Orme (2013) suggested that this component would be activated during times when greater attentional control was needed throughout a task. Similar suggestions have been made from Lavric, Forstmeier and Rippon (2000) who demonstrated a heightened P300 with a task requiring several visual and verbal cognitive functions.
The use of the visual specific N200 and the verbal specific N400 can give current researchers an indication of the domain specific or multicomponent nature of the quantitative and qualitative change detection tasks. If both the N400 and N200 are activated during each task then these can be discussed in terms of multicomponent approaches (Logie, 1995, 2011). If only the N200 is activated, then support can be provided for the more domain specific approaches to visual working memory architecture of change detection protocols (Baddeley, 2000, 2012).
2.3.3 The Relationship with Verbal and Non-verbal Ability
The work of Fukuda et al. (2010) proposed strong links between quantitative measures of working memory capacity and intelligence (also known as ability or reasoning ability), with the ability for this measure to predict non-verbal intelligence. In their investigation, two change detection tasks were presented to participants with one using quantitative array
45 changes and a second using qualitative array changes. Fukuda et al. (2010) indicated a two factor model for the prediction of intelligence, with the quantitative measure of working memory capacity providing a significant contributor to the intelligence measure scores, unlike the qualitative measure.
In contrast to this, a developmental investigation from Heyes et al. (2012) suggested strong links between qualitative measures of working memory capacity and intelligence in children aged 7-13 years. As previously discussed during this chapter, a qualitative measure of a bar orientation task was implemented to look at the precision of the children’s memory. These precision measures were shown to share a large amount of variance with the children’s’ Full Scale IQ scores, indicating that qualitative visual working capacity measures can also have a strong link to intelligence as well as the quantitative measures previously proposed by Fukuda et al. (2010).
In discussing the overall aim of the current thesis, to look at whether domain specific representations or multicomponent representations are being used by the change detection tasks, a piece of research from Shah and Miyake (1996) is one to discuss here. Shah and Miyake (1996) investigated the domain specificity of both spatial and verbal working memory resources in relation to spatial thinking tasks and language processing tasks.
Experiment 1 carried out correlations between all measures finding that spatial arrow spans had strong correlations with spatial ability tasks. In contrast, reading span measures had strong correlations to verbal SAT scores, proposing a more domain specific approach to verbal and spatial working memory measures. In their second experiment, similar results were found to that of experiment 1 even when the task type was taken into consideration (processing or storage). Regressions were carried out between the simple and complex processing version of the verbal and spatial tasks to discover if the language processing abilities and spatial thinking abilities could be predicted. Conclusions were made suggesting
46 that tasks which can have high demands of verbal processing and storage predict language processing. Similarly, tasks that can have high demands on spatial processing and storage can have the ability to predict performance on complex spatial thinking tasks.
As with Shah and Miyake (1996), the current thesis will aim to look at the domain specific versus domain specific question with regards to the quantitative and qualitative change detection protocols. If these tasks can only predict non-verbal intelligence measures, then a domain specific nature of these tasks can be suggested in a similar way to that of Shah and Miyake (1996; see also Shipstead & Yonehiro, 2016).
To assess the nature of the representation used within the quantitative and qualitative change detection task in the current thesis (domain specific versus multicomponent), a developmental investigation will be conducted to discover whether each change detection task has the ability to predict verbal and non-verbal intelligence. As the current thesis aims to focus not only on non-verbal intelligence measures, Wechsler’s Abbreviated Scale of Intelligence (2011) will be used. This measure has separate sub-scales for both verbal and non-verbal intelligence measures, meaning that two separate scores will be given for the verbal and non-verbal intelligence tasks. Fukuda et al. (2010) had used Ravens Advanced Progressive Matrices (1939) as the intelligence measure. The current doctoral thesis could not use this measure as Ravens Advanced Progressive Matrices does not offer a complementary form of verbal reasoning ability.