The aim of the current investigation is to investigate the cognitive resource demands of visual representation in the quantitative change detection task by using a dual task context. Adding in a secondary task, of either verbal attention (verbal parity task) or visual attention (bar fit task) will allow researchers to establish which working memory components are being used during the task. The verbal parity task (Lépine et al., 2005), will be used as verbal specific interference, and the bar fit task (Vergauwe et al., 2009) will be used as visuospatial interference as this has the potential to hit both visual and spatial working memory components. As each interference task makes use of a different working memory component, it is hoped that researchers can gain an understanding of whether a multicomponent (Logie, 2011) or a more domain specific (Baddeley, 2012) working memory model can be used here to explain the working memory architecture of the quantitative change detection task.
105 5.4 Predictions
1) From a Luck and Vogel (2013) view, the bar fit task (visual attention task) will have the greatest effect on the primary visual memory task.
2) From a Luck and Vogel (2013) view, the verbal parity task will not affect the primary visual memory task, meaning verbal semantics will not contribute to results. This would demonstrate a domain specific resource use as suggested by Baddeley (2012).
5.5 Method 5.5.1 Design
A 3 x 2 repeated measures design was used for the purposes of this experiment. Factor 1 was the interference type containing 3 levels – baseline, visuospatial interference, verbal interference. Factor 2 was the array size consisting of either size 4 or 6.
5.5.2 Participants
19 participants (14 females and 5 males, with a mean age of 23 and a standard deviation of 4.48) from the area of Newcastle-upon-Tyne volunteered to take part in this investigation.
Those who were Undergraduate Psychology Students received four course credit points for their participation in the experiment. Participants were aged between 18 and 30 years and had no record of any condition such as photosensitive epilepsy or colour blindness as these conditions could be affected by the experimental tasks.
5.5.3 Materials
12 short e-prime programmes were created for the purposes of this experiment. These included 4 practice tasks (two primary practices, a verbal parity practice and a bar fit practice) and 4 baseline tasks (two primary baselines, a verbal parity baseline and a bar fit
106 baseline). 4 dual task experimental programmes were then used. Each array size (4 and 6) contained one of each of the interference procedures from Verbal Parity and Bar Fit tasks.
As well as the e-prime tasks, instruction sheets were created to explain the primary Change Detection Square Task, Verbal interference and Visuospatial Interference. These instruction sheets included example images of the tasks plus instructions of which keys to press on the keyboard for a yes/no response. See Appendices A, D and E for examples of the instructio4s for participants.
5.5.3.1 Primary Colour Change Detection Task
Array sizes 4 and 6 were used from the pilot of the quantitative stimuli (chapter 3, experiment 3) for the encoding arrays. Only central peripheral location retrieval arrays were used for the purpose of this experiment. E-Prime 2.0 was used to create each task. Please see the methods section in chapter 3 for further details of this task.
Each primary e-prime task consisted of only 20 trials. In each trial, the encoding array was presented for 500 milliseconds, followed by a maintenance array of 4000 milliseconds.
Finally, a retrieval array was presented for 3000 milliseconds. please see Figure 5.1. for an example of a trial for this task.
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Figure 5.1. An example of one quantitative task trial containing the square stimuli.
5.5.3.2 Secondary Task, Visuospatial Attention – Bar Fit Task
A visuospatial attention task (Bar Fit Task) was presented in the 4000 millisecond maintenance interval. In this task, participants were presented with three sequential images.
Each image contained one bar that was placed just above two other bars. Each bar image was displayed for 800 milliseconds and there was a 400 millisecond blank image between each bar image.
When each bar image was presented, participants had to decide if the top bar was able to fit between the lower two bars, pressing the appropriate key on the keyboard – ‘q’ for no fit and
‘p’ for fit’.
The bar fit task has been suggested to inhibit the use of visual and spatial domain specific resources and therefore inhibits the rehearsal of any visual information within the visual working memory components such as the Visual Cache or VSSP (Vergauwe et al., 2009).
Please see Figure 5.2. for an example of this task.
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Figure 5.2. An example of a quantitative task trial including visual attention interference.
5.5.3.3 Secondary Task, Verbal Attention – Verbal Parity Task
A verbal attention task (Verbal Parity Task) was presented in the 4000 millisecond maintenance interval. Each number was verbally displayed for 800 milliseconds and there was a 400 millisecond blank interval between each number. In this task, participants listened to three sequential numbers and had to decide if each one was odd or even, pressing the appropriate key on the keyboard – ‘q’ for odd and ‘p’ for even,
The verbal parity task has been suggested to use and inhibit phonological domain specific resources (Lépine et al., 2005) and prevents the rehearsal of verbal information in the
109 Phonological Loop within working memory. It has also been suggested that tasks such as this can use general attention executive resources (Brown and Wesley, 2013). Please see Figure 5.3. for an example of this task.
Figure 5.3. An example of a quantitative task trial including the verbal attention interference.
5.5.4 Overall Procedure
The current investigation was ethically approved by the University Health and Life Sciences Ethics Committee. An information sheet and a consent form were given to participants at the start of the investigation. As there were 12 different components to this experiment, all task orders and instruction sheets were randomised for each participant to reduce fatigue effects and practice effects. Please see appendix G for an example of the task order.
110 The total testing session lasted one hour. Each task was fully explained to participants using visual diagrams before the testing phase began.
Participants were guided through the experiment and were given the appropriate instruction sheet or task. Participants were asked to work through the task and inform the researcher upon completion so that the programme could be changed to the next one. Once all tasks had been competed, participants were fully debriefed, thanked for their time and were reminded of their right to withdraw.
5.5.5 Scoring of all tasks
Participants were awarded 1 point for a correct change detected and 0 points for an incorrect response and all tasks could have a maximum of 20.
Within the dual task paradigm, the verbal and visuospatial attention tasks totalled 60 due to the three different memory probes in each trial. In this case, averages were taken of the three memory probes and averages again could have the highest score of 20. This allowed researchers to compare the results of both primary and secondary tasks using a similar measurement of working memory capacity (out of 20).
5.6 Results