Additional Parameters, Tasks, and Training In the training intervention there are a couple of parameters that can be altered

across all tasks. It is possible to vary the inter trial interval (ITI) for each task separately. The ITI is the period of time between when the last trial ended and the next trial begins. The successful completion of a trial is easier when this period is of a set predictable duration. The ITI was typically set to 500ms for all task types initially, then based on the session number and the participant’s performance on the individual task types, the ITI was firstly made variable (300ms to 800ms) and latter increased in the range of variability (300ms to 1000ms). Greater variability trains up sustained attention, the maintenance of a response readiness, and when the interval is particularly short a fast reaction time.

A movement allowance parameter was created that allows for the increasing and decreasing of the accuracy threshold of the eye-movements required for a response to be considered within a target range (the boundary of a region of interest). For some participants the eye-tracker can become more inaccurate across a session. Usually this is due to subtle shifts in their head position. Recalibration is not always the best option as it takes time away from the training, and additionally these subtle movements may occur more frequently towards the end of a session and would thus necessitate multiple recalibrations. At the same time the problem must be

addressed. If participants are repeatedly receiving negative feedback despite the fact that they move to the correct location within the response window this will hinder their training and they additionally may become frustrated. It was felt that in such instance loosening the accuracy threshold is a solution. A movement allowance

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parameter was thus created to alter the saccade accuracy requirement. The movement parameter was not needed for the current proof-of-concept study.

A number of additional tasks were also created. While a single block of these tasks were given to individual participants to assess their feasibility they were not used as part of the training program. It was felt that their inclusion would constitute an excessive load in terms of the number of tasks participants would have to learn.

For this purpose the Jumping Bomb, Sudden Distractor, Fixation, Double Shot, Distractor, and Building Bomb tasks were developed. The Double Shot task,

Distractor task, and Building Bomb task were dropped from the training intervention proof-of-concept study in the interest of simplicity and to reduce the cognitive load association with participants learning additional tasks. However these additional tasks may be utilised in future iterations of the game.

The Distractor task

This task is a simple prosaccade task with the addition of distractor bombs. The gaze must be shifted to the target bomb within a response window to succeed in a trial. Distractor bombs can appear before, simultaneously, or after the target bomb. The fixation point in the centre of the screen may or may not disappear. The distractor bombs may appear in a static position, may appear vibrating in a single position, or may shoot across the screen. If the participants look at a distractor bomb they fail the trial.

Building bomb task

This task is a prosaccade task but additionally requires that the gaze is maintained for a two second period before the bomb blows up. Distractor bombs also appear in an effort to draw the fixation away from the target bombs.

Double shot task

This is also a prosaccade task but the target bomb that appears must be zapped twice. The participants must first look at the bomb, then back to the centre of the screen and then back at the bomb again within a response window.

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While each game task had a particular training focus the structure of the game itself also trained certain skills.

 A useful feature of using the eye-tracker is that it is possible to ensure that the participant’s attention is directed back to the centre of the screen at the start of each trial, that is, the trial will not begin if they are not looking at the cross in the centre. This is a form of attention and procedural training.

 For each task there is then a period in which they should continue to fixate at the central fixation cross. Moving within this period resulted in the on-screen message “Wait”, and the trial then began again. This helped to develop sustained attention and to maintain fixation, and also ensured that the participant was settled before each trial.

 For different participants the training also involves training in skills such as frustration control and resilience to negative feedback. After failing a trial or a poor block performance, participants need to continue attempting to succeed. The importance of self-regulation skills should not be underestimated in individuals with ADHD who typically have experienced a large amount of

negative feedback and adverse learning experiences in the past. Where present such experiences and the development of a negative response pattern to failure, such as avoidance, can act as a barrier to learning and need to be addressed. In the course of delivering the intervention disengagement and frustration were observed in some participants in response to negative performance feedback. An advantage of having immediate trial feedback is that it provides participants with the opportunity to experience that attempting after failure can lead to

improvements. Lessons such as these can be harder to identify when the task in question is large, complex, or if the feedback is not delivered for a long time. In a gaming environment the relationship between behaviour and its consequence are more readily identified and highlighted, especially when feedback is

immediate and is subsequently reflected upon at the end of the block. While this was not the intentional focus of the training intervention, the participant’s attitudes to negative feedback, their ability to manage frustration, and the belief that they can improve set the context within which the intervention is delivered. As such it is important, where possible, to factor in such concerns. These concerns also highlight the critical importance of pitching the difficulty of the

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tasks at the right level. In cases where participants are getting frustrated there may be a need to reduce the difficulty to facilitate a higher success rate.