# A Personalised Emotion-Based Model for Relaxation in Virtual Reality
## Experimental Evaluation
### Discussion  
The results on the order of the adaptations have indicated that each user has an optimal order for the adaptations to occur in, this order depends entirely on the profile of the user. In fact, an algorithm in the form of a decision tree can be constructed which selects the optimal order. Before constructing this decision tree, the findings which lead to the algorithm are summarised. For the outdoor environment it was observed that natural light and dog should occur early in the sequence and music and fire can occur near the end. However, when natural light has a low optimal value, and therefore had little impact, the optimal sequences would end with natural light instead. More specifically, the set of optimal sequences are \(dg\), \(nl\), \(py\), \(ms\); \(dg\), \(nl\), \(ms\), \(py\); \(nl\), \(dg\), \(py\), \(ms\); and \(nl\), \(dg\), \(ms\), \(py\). Expect if natural light has a low optimal value, than the optimal sequences are \(dg\), \(py\), \(ms\), \(nl\); and \(dg\), \(ms\), \(py\), \(nl\). Since the indoor environments contain other adaptations as well, different rules apply. It was observed that every sequence should end with artificial light and that dog should also come before controlled breathing. However, when artificial light and dog are not enabled because their optimal value is too low, the sequence should simply end with controlled breathing. Structuring this logic into a decision tree results in Figure 14. This tree can be used to reduce the set of all possible permutation of adaptions to a small set of sequences which are guaranteed to perform better than any other sequence. Depending on the available computing power, a simulation can be run to select the very best sequence from this reduced set, or a random sequence can be selected. This result, which shows that different sequences result in a different outcome, indeed proves that personalisation is needed. Additionally, it is shown that through the described algorithms this personalisation can be achieved. More complex algorithms and more data could potentially further improve the benefits of a personalised approach. For example, the addition of biofeedback could ensure a quicker and more accurate response to changes in emotion and behaviour of the patient. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**No.**} & \multicolumn{4}{c}{**Sequence**} & \multicolumn{3}{c}{**Average**} & **Final** \\  & & & & & & **Relaxation** & **Relaxation** \\ \hline \(1\) & \(lc\) & \(dg\) & \(ms\) & \(cb\) & \(nl\) & \(al\) & 0.782 & 1.000 \\... & & & & & & & \\ \(72\) & \(ms\) & \(nl\) & \(dg\) & \(cb\) & \(lc\) & \(al\) & 0.736 & 1.000 \\ \(73\) & \(lc\) & \(dg\) & \(ms\) & \(cb\) & \(al\) & \(nl\) & 0.793 & 0.996 \\... & & & & & & & \\ \hline \(221\) & \(dg\) & \(nl\) & \(al\) & \(cb\) & \(ms\) & \(lc\) & 0.759 & 0.982 \\... & & & & & & & \\ \(276\) & \(ms\) & \(al\) & \(nl\) & \(dg\) & \(cb\) & \(lc\) & 0.751 & 0.982 \\ \(277\) & \(dg\) & \(al\) & \(lc\) & \(ms\) & \(cb\) & \(nl\) & 0.793 & 0.972 \\... & & & & & & & \\ \(360\) & \(al\) & \(ms\) & \(nl\) & \(dg\) & \(cb\) & \(lc\) & 0.745 & 0.972 \\ 361 & \(lc\) & \(nl\) & \(ms\) & \(al\) & \(cb\) & \(dg\) & 0.719 & 0.858 \\... & & & & & & & \\ \(528\) & \(cb\) & \(ms\) & \(al\) & \(nl\) & \(dg\) & \(lc\) & 0.622 & 0.858 \\ 529 & \(lc\) & \(nl\) & \(al\) & \(cb\) & \(dg\) & \(ms\) & 0.720 & 0.848 \\... & & & & & & & \\ \(660\) & \(cb\) & \(al\) & \(ms\) & \(nl\) & \(dg\) & \(lc\) & 0.621 & 0.848 \\ 661 & \(al\) & \(lc\) & \(nl\) & \(ms\) & \(cb\) & \(dg\) & 0.719 & 0.838 \\... & & & & & & & & \\ \(720\) & \(al\) & \(cb\) & \(ms\) & \(nl\) & \(dg\) & \(lc\) & 0.644 & 0.838 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Effect of different adaptation sequences on the final and average relaxation for indoor environments. The list is ordered according to decreasing final and average relaxation. The highlighted sequence is the order used in the heuristic implementation.