Complexity versus specificity

A major consideration when developing a training intervention is deciding how targeted it should be, that is, what level of complexity should the training task contain, how general or specific should the tasks be with regards to the function identified? In their review paper on improving intelligence Buschkuehl & Jaeggi (2010) stipulate three criteria for successful training: (1) the task should minimise the development of task specific strategies; (2) the training must be adaptive, that is, utilise some form of algorithm that adjusts difficulty in the light of current performance, and (3) the task should be complex enough to train several different processes at once in order to maximise process overlap with other tasks, and thus facilitate transfer.

The alternate view is that training programs will typically need to avoid complex tasks, for instance most real-life tasks. Success on complex tasks requires integrated knowledge, and appropriate skills and attitude (Merrill, 2002). Training by

completing complex tasks, while more ecologically valid, places a high load on the trainee’s cognitive system and typically takes individuals who are committed (for instance learning a sport or musical instrument) out of genuine interest years to master (ten year rule, Simon & Chase, 1973). A well-designed training program will encourage deliberate practice in a specific domain critical to the success of the complex or real-life task; this is referred to as high fidelity (Van Merrienboer, 1997). Bilinguals and individuals with Tourette syndrome display enhanced inhibitory control, but in both cases we provisionally attribute this to the prolonged intense exercising of the cognitive systems involved. It should be noted that Buschkuehl, and Jaeggi recommendations pertain to the development of intelligence generally. Perhaps this is the critical distinction to be made; are we seeking to train the cognitive system generally or are we focused on developing a specific function? In this instance we are focused specifically on training-up an underdeveloped cognitive ability with latent capacity.

Buschkuehl & Jaeggi (2010) suggest that complexity may be a critical aspect of encouraging transfer of the learned skill. However, the more complex the task the more likely that there are multiple solutions and solutions that are less reliant on the

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target of the training. If there is a weakened function and multiple solutions are possible, we might expect the selection of a solution that avoids the use of the weakened function. A better performance does not necessarily mean they are

learning the intended target. For example, improved performance may be dependent on a limited strategy reliant on compensatory skills that are sub optimally using cognitive resources. Bad technique can often lead to improved performance but with little chance of progression beyond a certain point. We can liken this to the training of a weakened muscle. It may be possible to compensate for a weakened muscle with the recruitment of the surrounding muscles and to improve on outcome measures such as speed or load bearing, but this is not optimal in the long term. Instead there is a need to strengthen the weakened muscle with specific isolation exercise, as seen with physiotherapy. Beyond the rehabilitation exercise there is also a need for the trainee’s genuine interest in strengthening the weakened muscle and understanding that simply compensating for this weakness will be limiting in the long-term. Tasks that are less specific that utilise multiple functions simultaneously will more readily lend themselves to successful completion with the use of

compensatory mechanisms, thereby circumventing the target of the training. In addition, in complex tasks with multiple solutions it is likely to be more difficult to identify reliable indices pertaining to the intended target. With a focused training task we can curtail the number of possible solutions and encourage the identification of more optimal or efficient solutions.

If the decision is made that isolating a particular function is a more reasonable approach, then what level of detail should be sought? Inhibitory control itself may be broken down into sub functions. A study by Hanisch, (2006) suggests that children with ADHD had an inhibitory deficit with regards to exploratory saccades and inhibiting an already initiated response. They were not impaired at inhibiting a pre- potent response. This result has not been consistently replicated but does highlight the potential need to deconstruct and separate different types of inhibitory control. However, this approach, attempting to isolate and strengthen a particular cognitive function or sub function, may not be viable.

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 It may not be practical, given that even the most basic tasks draw on multiple cognitive skills. The level of detail that can be reliably isolated will reflect the sensitivity of the measurement techniques used. For the current intervention this will be the ocular indices extracted.

 It makes the assumption that the impairment relates to a specific function as opposed to the coordination of multiple functions.

 It places a higher demand on identifying with a high level of precision the deficit to be targeted.

 The more specific the target of the training the more specific the population it will benefit. This may not be desirable given the heterogeneity of the ADHD population. For the purposes of the current training intervention we are not seeking to train a specific sub-population of the ADHD population.

Expanding on this final point, it may be possible and beneficial to develop specific inhibitory control interventions for ADHD sub-populations, for example, in an anti- saccade task predominantly inattentive and combined subtypes were found to have different response patterns (Loe et al., 2009). Children with ADHD combined type had increased anticipatory movements and increased fixation time. However, this intervention in the first instance aims to develop a one size fits all intervention. If this proves to be unachievable due to heterogeneity then specific interventions targeting sub populations within the ADHD population may be necessary. The reasonable approach is to first attempt to reliably identify a specific inhibitory deficit in the general ADHD population.

With regards to achieving a balance between complexity and specificity in the training intervention, the ideal solution might be to initially isolate the targeted skill early on to prevent the use of compensatory mechanisms, and later increase complexity and similarity of the task to real life to encourage its integration with other functions and transfer (as a side point, there may be additional tangential skills that need to be strengthened in order to support transfer). This approach would help ensure the intended target is strengthened early while avoiding the use of

compensatory strategies, but subsequently securing the flexibility and sustainability of the function by ensuring it can be used in conjunction with other functions and that there is a potential functional utility to its use. Such an advanced approach is

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beyond the scope of the current project. The focus of the intervention will be to strengthen the intended target, inhibitory control and aspects of timing and attention, but it is beyond the scope of the intervention at present to seek to integrate these targeted functions into everyday functioning.

To summarise, the use of complex tasks may offer trainees an opportunity to complete tasks using compensatory mechanisms and thus bypass the target of the training. Due to the discounting of delay rewards associated with ADHD this may in particular be a problem with this population, that is, they may focus on the short- term aim of completing the task successfully by any means as opposed to focusing on the longer-term benefits of developing an underdeveloped skill. By using a training intervention with simplified tasks it may be possible to curtail the degree to which the intended target can be bypassed with compensatory strategies and it will be easier to highlight the potential benefits of investing in the underdeveloped function. Additionally, it may be difficult to identify reliable indices of specific

functions when complex tasks are used. The training intervention will avoid complex tasks that offer the potential to avoid the use of inhibitory control. Conversely, if the tasks used are overly specific they may only be beneficial for a sub-group of the ADHD population. The intervention will also not target a specific component of inhibitory control, e.g. reflective component; it will target multiple aspects of inhibitory control with a number of tasks. In this way the targeted function will be used in conjunction with different constellations of functions for different tasks. This approach if successfully will balance the issues around complexity and specificity.