Effect of Emotion-Related Parameters
Effect of α2 parameter
Parameter a2 represents the trade-off between rational and emotional behaviour and it is included in Eq. (9.7). Higher value of a2 parameter implies a more emotionally driven behaviour. As it is explained in Psarra et al. (2014), higher influence of affective responses results in spending more effort in exploring new alternatives. This is because after a negative experience there is a high chance that in next choice an agent will try to explore another alternative. Additionally, even when positive emotions are experienced; the activity profile may not perform structurally well, which also increases the possibility that in next choice an agent will need to find another solution. The increased number of explored activity profiles leads to an increase of the average choice-set size, as it is indicated by the trend line in Figure 9.9.
Moreover, as a2 increases, aspiration values tend to decrease. This is because emotionally driven behaviour leads to more exploration efforts, which, in turn, result in more lowering aspiration incidents. Consequently, when an agent focuses more on emotional responses when making a decision, it is getting easily dissatisfied
Figure 9.9: Effect of a2 parameter on choice-set size.
Figure 9.10: Effect of a2 parameter on aspiration values.
and its aspiration values tend to decrease (Figure 9.10), in order to become more realistic and allow the development of habitual behaviour. Finally, it should be mentioned that as the aspiration values get lower, the probability that a long-term change is decided increases. Thus, emotionally driven behaviour brings more short and long-term dynamics into the system.
Effect of α2 parameter
Parameter represents the trade-off between accumulated past emotional values and the most recent ones. When approaches 1, the emotional value of an activity profile is totally influenced by the most recent emotional experience event. Accordingly, as approaches 0, past emotional experiences are taken into account to a greater extent. Undoubtedly, the salience of the effect of parameter on model behaviour depends on the value of parameter . For instance, in case that is too low, emotions are not taken into account during the decision-making process and, therefore, the influence of on the model behaviour will be very small. On the other hand, if approaches 1, affective responses influence to a great extent the evaluation of alternatives and the trade-off between recent and accumulated past emotional experiences can play a significant role on the decision-making process and the overall model behaviour.
As it is depicted in Figure 9.11, when the value ofincreases, the frequency of exploration behaviour also increases. This implies that when the choice-making process is based only on the most recent affective responses, more effort is spent in exploring new alternatives, while habitual behaviour decreases. Finally, the intensive exploration behaviour results in an increased frequency of the lowering aspiration incidents.
When the value of parameter α1 increases, the overall expected utility of the exploitation and exploration choice mode tends to decrease (Figure 9.12).
Figure 9.11: Effect of α1 parameter on frequency of choice modes (exploitation, exploration) and lowering aspiration incidents.
Specifically, when the decision-making process is based to a greater extent on the most recent emotional experience events, the agents tend to get more easily disappointed and conduct more exploration effort. Consequently, much more activity profiles are explored, many of which do not perform very well. This results in a decrease of the mean overall expected utility of the exploration choice mode. Similarly, the overall expected utility of the exploitation choice mode tends to decrease, as well. This is explained by the fact that more lowering aspiration incidents take place, as α1 increases.
If the value of parameter α1 increases, the mean overall expected utility of the agents' choice sets decreases (Figure 9.13). This implies that when taking into
Figure 9.12: Effect of α1 parameter on overall expected utility of choice modes (habit, exploitation and exploration).
Figure 9.13: Effect of α1 parameter on choice-set overall expected utility.
Figure 9.14: Effect of α1 parameter on aspiration values.
account only the most recent emotional experiences and not the accumulated past emotional experience, the evaluation of the alternatives and the decision-making process leads to more explorations and ultimately to a decrease of welfare over time. This result is plausible and it is also in line with the fact that the overall expected utilities of the exploitation and exploration choice modes are also in decreasing trend. Finally, the decreasing trend line of the aspiration values in Figure 9.14 is explained by the increased frequency of the lowering aspiration incidents. This result is also reasonable, as when the decision-making process is only based on the most recent emotional response, the agents get easily disappointed and become engaged in a more intensive exploration behaviour. Ultimately, this results in a decrease of their aspirations (in order to manage to develop habitual behaviour at some point of time), which, in turn, increases the probability that long-term dynamics emerge.