3.2 The OCC model
3.2.1 Revisited model
However hard they tried to make the OCC model computational it did contain ambiguities and the lack of logical approach has made it harder to implement.
Looking at 3.1 we see that the model is a flow diagram of how the emotions are constructed but from a computer science perspective the figure could be formed as a inheritance diagram, especially since that joy and distress are default emotions for the branch ”consequence of self”.
Through out the book they use ”desirable event” but looking at it we are not interested in the event but rather the consequence or outcome of an event. An earthquake in it self is not of relevance but rather the consequence it produce has such as the damage it carries or lost of life.
Another problem is in the Prospect-based emotions where fear can lead to dis-appointment and satisfaction but neither of these two emotions spawns from fear as both arise from a desirable event. The same can be said about hope as neither relief or fear-confirmed has anything to do with hope.
The fortunes of other emotions can be related to the well-being emotions since
”happy-for” is when an outcome is considered desirable for others and in so must also to some degree be desirable for on self and the thus the feeling of ”joy” is experienced. For example, being happy for another for completing a difficult task since they desired it also means that it was desired that they succeeded an happy that they did. This means that the term focusing on and prospect irrelevant is not suitable any more and logical incorrect, since ”happy-for” implies
”joy” then the focus is also on oneself.
The aspect of objects is also considered to be in need of improvements as there are no conditions to distinguish love/hate from the generalized liking/disliking.
For approving/disapproving, pride/shame and admiration/approach is differen-tiated by who performed the action and for pleased/displeased the emotions hope/fear and joy/distress is differentiated by the one being a prospect and the
3.2 The OCC model 23
other an actual consequence. love/hate does use familiarity but is only used to further the intensity where the more familiar an agent is with an appealing object the more it is loved and the more familiar a unappealing object the more it is hated.
In 2009 a revisited model of the OCC model was proposed by three computer scientist in order to create a standardized interpretation of the psychological OCC model for other computer scientist wishing to formalize or implement emotions [SDM09]. This revisited model removed and clarified the ambiguities mentioned above along with other ambiguities and restructured the model to a more logical structure in order to make the model easier to implement and work with.
Figure 3.2: Revisited structure of emotion in the OCC model. [?]
The new inheritance model of the OCC model seen in figure 3.2 have removed
the idea of groups and many of the emotions are now split up. All of the men-tioned ambiguities are solved so now the emotions such as satisfaction and relief along with happy-for and resentment or now specializations of the feelings joy and distress. With that, hope and fear are now for themselves but as it is an inheritance diagram then hope is still not excluded as logical part of satisfaction.
The aspect of objects are also more defined with the aspect of familiarity intro-duces which give rise to two new emotions interest/disgust where familiarity is used to distinguish between love/hate.
Chapter 4
Modelling Emotions
Multiple articles have constructed a logical formalized emotions for BDI-agents using the OCC model as a basis. All of these framework establish a syntax with a language containing predicates similar to the predicates in a BDI-agent and GOAL-agent such asBelfor beliefs andGoal for goals of an agent.
Meyer who also proposed the revisited OCC model had formalized emotions before using the original OCC model along with an existing an framework called KARO in 2 different papers [Mey06, SDM07]. In both papers the formalization was focused heavily on the agents planning and action as the formalization has definition for the agents commitment to a plan along intention of accomplishing a goal through execution of a plan. However the formalizations was made with the OCC model in mind yet the only defined emotions in the article [Mey06]
wereHappines, Sadness, AngerandFear. The [SDM07] formalization had even less as it only dealt with 2 emotions,HopeandFear.
Another formalization was made by Herzig and Longin based on the original OCC model in 2006 ([AGHL06]) and refined in 2009 ([AHL09]). Both paper defines operators with temporal logic such as (Hϕ) that reads ”ϕ has always been true” and (Gϕ) that read ”Henceforthϕ is going to be true” in order to define all the 22 emotions in the OCC model. A unique operator is also defined called Expect which simply defines if an agents expects an event and is used to in the logic for prospect based emotions e.i. hope and fear.
Another paper, [GLL+11], formalized emotions with very few operators unlike the other two formulations. It is also based on the OCC model but only imple-ments 12 emotions with only a few of them the same as the OCC model, besides formalizing emotions a wide variety of expressions between agents are made. In this paper three operators deviate from the other formalizations: Idealdefining the moral state of the agent,Cddefining the the agents action and choices and Expdefining that an agent express a formula to another agent. The operator Cdis used to define a new operator called Respwhich states that an agent is responsible for an outcome.
4.1 Formalizing the OCC model
Based on the OCC model and the different proposed formalization of the OCC model, a new logical framework will be proposed in trying to formulate emotions in the revisited OCC model. However, as the formalization will be used to implement emotions in agents in GOAL it has to be compatible with GOAL. But some of the proposed intensity variables in the OCC model can’t be implemented in GOAL in it’s current form as GOAL lack the function needed to define the some of the variables.
There are generally two approaches the OCC model can be implemented in a BDI-agent, one is a form of interpretor for the agent state of mind in to emotions.
Implemented in GOAL means that the agents state of mind is interpreted each cycle and the emotions intensity are calculated each time and checked with the threshold in order to determine if they are still relevant. However has GOAL removes goals when they are achieved then the agent will only be able to feel emotions such as satisfaction and relief as it is possible to see an prospected event has been realized but any recurring cycle will not be able to see this making it an unsuitable approach for GOAL. The other way is to use the state of mind to create persistent emotions in the agents state of mind where the emotions are given a intensity when they are realized and will slowly decay until they are not relevant any more.
Emotions regarding appraisal of agents action make use of the variable ”Strength of unit” and this variable requires that the agents has some sort of model between the agent it self and others defining social groups or organizations such as family, workplace, friendships. This model does not exist in GOAL and implementing it in GOAL is out of this scope, however previous work has been done in this area such as [Spu13] which could be used in order to implement this variable.
Another variable that cannot be realized in GOAL is the variable ”Deviations of
4.1 Formalizing the OCC model 27
the agent’s action from person/role-based expectation”, i.e the unexpectedness of an agent. In order to have this variable the agent is required to have a model of other agents or place it self in another agents position and attempt to predict what that agent would do in its given position and be able to compare it with what the agent actually did and be able to quantify it
The same is the problem with the global variable ”Unexpectedness”. It is possible if it was just used to decide if something was expected or not but as it used as a variable the agent should be able to quantify the unexpectedness.
The ”proximity” variable is somewhat possible to implement with linear temporal logic but it requires that the outcome of events has a timestamp so it is possible to determine the proximity to the agent but the added information will make it difficult to store in GOAL as it needs to store the timestamp as well as info of the event.
Additionally it was proposed in the OCC model that the variables for emotions should be weighted as they don’t have the same impact on an emotion but never stated what this distribution should be, so in an attempt to limit the amount of work in this thesis all variables are weighted equally.
Love and hate along with interest and disgust is not going to be part of the logical formalization as these emotions requires first order modal logic to be implemented as stated in [AHL09], however an alternative implementation for love and hate will be proposed later.
The last variable that will not be present in the framework is the global variable
”arousal” as this is a physiological state of a person and as the agent is purely cognitive. Such a physiological state can be simulated in the agent but is out of the scope of the thesis.
Removing these variables from the framework would reduce the correctness of the intensity but will not render the intensity for the affected emotions obsolete as these emotions has other variables that factor in to their respectively intensity.
Finally, as neither GOAL or Prolog support temporal logic then the logical formalization will refrain from using these.
Based on these limitation a new inheritance model for the emotions for this thesis can be seen in figure 4.1.
pleased displeased Valence Reaction
Approving Disapprobing
Action (of Agent) pleased
displeased Outcome (of Event)
Prospective Outcome
hopefear joy
distress Actual
Outcome Self
Agent pride
shame admiration
reproach Other Agent
Related Outcome and Action gratification
remorse gratitude anger Related Outcome and Action
Outcome Confirms Prospective
Desireable Outcome satisfaction
---
---fears-confirmed Outcome Confirms Prospective Undesireable
Outcome
Outcome Disconfirms Prospective Undesireable Outcome
relief
---
---dissapointment Outcome Disconfirms Prospective Desireable Outcome
Consequence Presumed
to be Desireable
for Other happy-for
resentment gloating pityv Consequence
Presumed to be Undesireable
for Other
Figure 4.1: The structure of emotion for the framework