Instrumental Actions: Goal-Directed and Habitual
An instrumental action is an action that happens in order to bring about an outcome. When you press a lever in order to retrieve a snack, or when you board a bus in order to travel home, you are performing an instrumental action. What grounds the relation between an instrumental action and the outcome it occurs in order to bring about? This section introduces a key distinction between two answers to this question, goal-directed and habitual.
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What is the relation between an instrumental action and the outcome or outcomes to which it is directed?
A Standard Answer
One standard answer to this question involves intention. An intention specifies an outcome, coordinates your actions, and coordinates your actions in a way that would normally increase the probability of the specified outcome ocurring. So if an intention causes you to act, it follows that your action happens in order to bring about the outcome intended. And this implies that your action is instrumental.
What is an intention? Although there is much debate about this (Setiya, 2014), for our purposes only a widely agreed characteristic is necessary. Intentions are the upshot of beliefs and desires (or are identical to one or both of these). To illustrate:
desire: I fill Zak’s glass.
belief: If I pour, I will fill Zak’s glass.
intention: I pour to fill Zak’s glass.
This simplistic example captures a key idea. Behind an intention lie two things. There is a desire to bring an outcome about, and there is a belief about which action will bring the action about.
If you would like more background on action and intention, see Lecture 10 of Mind and Reality.
Our Main Question is about the relation between an instrumental action and the outcome or outcomes to which it is directed. According to the Standard Answer, the relation involves belief, desire and intention:
Background Assumption: Instrumental actions are caused by intentions to bring outcomes about, which are the upshot of desires to bring outcomes about and beliefs that certain actions will bring them about.
Standard Answer: The outcome (or outcomes) to which an instrumental action is directed is that outcome (or outcomes) specified by the intention (or intentions) which caused it.
A Clue from Animal Learning
According to Dickinson (2016, p. 177):
‘instrumental behavior is controlled by two dissociable processes: a goal-directed and an habitual process’
He goes on to specify what the ‘goal-directed process’ involves:
‘an action is goal-directed if it is mediated by the interaction of a representation of the causal relationship between the action and outcome and a representation of the current incentive value, or utility, of the outcome in a way that rationalizes the action as instrumental for attaining the goal’ Dickinson (2016, p. 177).
Dickinson’s ‘goal-directed process’ corresponds to the belief--desire model we just considered. The ‘representation of the causal relationship between the action and outcome’ could be a belief about which action will bring an outcome about (e.g. the belief that if I pour, I will fill Zak’s glass). And the ‘representation of the current incentive value, or utility, of the outcome’ could be a desire.
|philosophy||animal learning||decision theory|
|belief||representation of the causal relationship between the action and outcome||subjective probability|
|desire||representation of the current incentive value, or utility, of the outcome||preference|
Table: rough correspondence between terms used for modelling action across three disciplines.
So when Dickinson says that instrumental actions are ‘controlled by two dissociable processes’, he is implying that the Standard Answer about belief, desire and intention cannot fully explain the relation between an instrumental action and the outcome or outcomes to which it is directed. If he is right, we also have to consider something he calls ‘an habitual process’.
What Are Habitual Processes?
Habitual processes involve connections between stimuli and actions. For example, the presence of an empty glass (a stimulus) may be connected to the action of pouring. These connections are characterised by two features:
When the action is performed in the presence of the simulus, the connection between action and stimulus is strengthened (or ‘reinforced’) if the action is rewarded.
If the connection is strong enough, the presence of the stimulus will cause the action to occur.
This is another way of stating _Thorndyke’s Law of Effect_:
‘The presentation of an effective [=rewarding] outcome following an action [...] reinforces a connection between the stimuli present when the action is performed and the action itself so that subsequent presentations of these stimuli elicit the [...] action as a response’ (Dickinson, 1994, p. 48).
How do habitual processes differ from those involving belief, desire and intention? Two differences are important for our purposes:
The effects of habitual processes do not depend on what you currently desire. This is because the strength of the stimulus--action connection depends only on what was rewarding for you in the past, not what is rewarding for you now.
The effects of habitual processes do not depend on what you currently believe about which outcome the action will have. This is because the strength of the stimulus--action connection depends only on what outcomes the action had in the past, not on which outcomes it will have now.
Because habitual processes have these features, we can be sure that they are genuinely distinct from processes involving belief, desire and intention.
Habitual Processes and Instrumental Action
Our Main Question is, What is the relation between an instrumental action and the outcome or outcomes to which it is directed? This question can be answered by invoking habitual processes. For if an action is due to an habitual process, then there is a stimulus--action connection which caused it. This stimulus--action connection must have been strengthened in the past because, often enough, some (one or more) rewarding outcomes occurred when the action was performed in the presence of the stimulus. But since habitual processes exist to enable the agent repeatedly bring about such rewarding outcomes, it follows that the action occurs now in order to bring about these (one or more) rewarding outcomes. That is, the action is directed to the outcome; it is an instrumental action.
The Standard Answer therefore fails to provide a full answer to the Main Question about instrumental action. To fully answer it we need not only belief, desire and intention but, minimally, also the kind of stimulus--action connections involved in habitual processes.
The next step is to investigate possible consequences for philosophical theories of action.
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You may variations on this definition of instrumental in the literature. Dickinson (2016, p. 177) characterises instrumental actions differently: in place of the teleological ‘in order to bring about an outcome’, he stipulates that an instrumental action is one that is ‘controlled by the contingency between’ the action and an outcome. And de Wit & Dickinson (2009, p. 464) stipulate that ‘instrumental actions are learned’.
Be careful not to confuse a goal with a goal-state, which is an intention or other state of an agent linking an action to a particular goal to which it is directed. (Some authors use the term ‘goal’ for goal-states rather than outcomes.) A goal is a possible or actual outcome (such as filling a glass with prosecco). A goal-state is a psychological attribute of an agent (such as an intention to fill a glass with prosecco). ↩︎