Adam et al

In a similar vein to Stunebrink et al. in section 4.2.1, Adam et al. also attempt to provide a logical formalism of the OCC model in [2]. The author’s reasons to model the OCC are numerous, the most salient being that the OCC model is widely used in the design of emotional agents. This is due to its simplicity and ease of implementation which matches the expectations and needs of computer scientists. It would therefore seem that the combination of the OCC model’s finite set of appraisal variables suffices for current applications. The authors also agree with the proposition of the OCC model that any emotion must be consistently valenced since this confers the advantage of providing a clear test to differentiate emotions from closely related notions that are not valenced. Furthermore, the authors argue that valence is something naturally captured by logic and computer science resulting in the OCC model being well adapted particularly for a logical formalisation. In addition, Adam et al. notes that the OCC model has a simple and elegant tree structure which facilitates tractability2. The OCC model also uses concepts that are well understood in logic such as beliefs, desires and standards thus making the formalisation task easier. Finally, the authors argue that the OCC model is quite exhaustive, an important feature if one is to design robust and versatile agents i.e. agents that can emotionally react to a broad variety of stimulus.

The aim of [2] is to account for relationships between the different components of emotions and relationships between an agent’s emotions and their performed actions (these topics are not accounted for in the OCC model). As such, Adam et al.’s formalism attempts to describe an agent’s mental attitudes such as beliefs, goals and desires with the aid of theELlogic and the BDI-focused framework developed by Herzig and Longin in [88].

Adam et al.’s formalism is restricted to the modelling of emotion triggering condi- tions thus, they devote no attention to the logical formalism of emotional experience (this is covered by Steunebrink et al., see section 4.2.1). The authors also restrict their formalism to event and action based emotions (objects are not considered) and con- sequently, the salient variables modelled are the desirability/undesirability of an event and the praise/blameworthiness of an agent’s action. It is argued that the desirability of an event is closely tied to the concept of utility i.e. the more positive the utility conferred by an event, the more desirable the event is and that the same event may be desirable/undesirable depending upon the circumstance i.e. the event is valenced. The authors recognise that this is problematic as such a feature makes a logical formalisation difficult due to its necessitation of “either a paraconsistent notion of desirability such

2_{This argument is made despite Ortony et al.’s assertion that the OCC model is more of a lattice}

that ‘ϕis desirable’ and ‘¬ϕis desirable’ are consistent, or a binary notion of desirability that is relativized to goals”.

Adam et al. tackle this issue by shifting the focus of an agent’s appraisal of an event or action to the consequence of that event or action in terms of the agent’s current goals. So, whilst an agent that has lost its job may have distress elicited due to the goal of “being employed” not being achieved, joy may be elicited since the agent may now achieve its goal of “pursue other interests”. The most important issue to comment upon here is that the “loss of job” event is neither desirable or undesirable, instead the consequences of that event are appraised in terms of the agent’s goals and the desirability of the event is determined in context of that goal. This follows the OCC model’s prescribed method of dealing with simultaneous opposing emotions unlike Steunebrink et al. who appear to propose their own method (see section 4.2.1).

The actions of agents are also modelled in much the same way i.e. there are two modal operators assigned to appraise the praiseworthiness/blameworthiness of an action in context of agent’s current standards (which are internalised). It is also asserted by Adam et al. that a consequence of an action cannot be appraised as being both praiseworthy and blameworthy if appraised in context of the same standard.

The logical formalism of emotion eliciting conditions is somewhat more complex than those proposed by Stuenebrink et al. with Adam et al. also taking time into account. Yet, whilst Adam et al.’s formalism models the qualitative aspects of emotions in much the same way as Steunebrink et al., there is a distinct lack of quantitative aspects consid- ered. This results in some important consequences of ignoring quantitative aspects the most important of which being: if the eliciting conditions for an emotion are met, then the emotion is always experienced. In other words, there is no gradual increase of an emotion’s potential before that emotion is activated. This is an important point since it is particularly problematic with respect to subjectivity of emotional experience. Essen- tially, if the eliciting conditions for an emotion are the same for two distinct agents and those eliciting conditions occur then both agents will experience the emotion in question with equal intensity (due to the lack of quantitative measures of emotional intensity). Furthermore, the lack of consideration regarding quantitative aspects of emotions means that emotions remain active so long as their conditions stay true which, depending on the application domain, may not be at all intuitive or desirable. Finally, the logical for- malism proposed by Adam et al. only takes into consideration the triggering conditions of emotions: it does not attempt to specify what effect the emotion’s activation has upon the beliefs, desires or intentions of the agent. As such, the usefulness of the model only extends to the qualitative modelling of eliciting conditions for emotions and in its consideration of simultaneous opposing emotion experience.