1. Dual process theories of reasoning: Types, systems and types of system Jonathan St B T Evans Centre for Thinking and Language School of Psychology University of Plymouth

2. Outline of the talk 1.Type 1 and 2 processing –The distinction between two types or modes of reasoning/processing assumed by dual-process theorists 2.Systems 1 and 2 –A generic classification of several dual-system approaches 3.Type 1 and 2 systems –An approach suggested by the philosopher Samuels I will identify problems with 1 and 2, suggest how 3 might be developed

3. Type 1 and 2 processing Dual process theories have become very popular in the study of learning, reasoning, social cognition and decision making. Type 1 processes: fast, unconscious, automatic, high capacity Type 2 processes: slow, conscious, controlled, low capacity The terms type 1 and 2 were originally used by Wason & Evans (1975). Evans (2008) encourages use of these terms due to problems with dual- system theory.

4. Problems with T1/T2 processes: 1. mechanisms vs thinking styles Some authors assume that such processes reflect distinct cognitive mechanisms: e.g. type 2 processing involves central working memory (e.g. Evans, Stanovich) Others refer to two modes of thinking (e.g. Chaiken and some other social psych theories) that may be akin to cognitive styles For example, are cross-cultural differences in thinking style (Nisbett, Norenzayan) related to dual process theories? Strong arguments that there are two different distinctions here (Evans, Stanovich)

5. Problems with T1/T2 processes: 2. slow vs fast processes Researchers often try to use the fast/slow process distinction to separate type 1 and 2. E.g. by using a speeded task, or measuring speed of response But there is a distinction between two types of fast process: intuitive judgements based on feelings of rightness (type 1) and heuristic judgements based on quick and lazy but explicit rules of thumb (type 2) These two kinds of fast judgement often get confused, e.g in recent books by Gladwell (Blink) and Gigerezner (Gut Feelings)

6. Problems with T1/T2 processes: 3. automatic vs controlled Who or what controls ‘controlled’ processes? The folk psychological concept of a conscious mind in intentional control of behaviour intrudes here The feeling of conscious will is illusory (Wegner, Bargh) Stated intentions and reasons are frequently confabulations (Wilson) Automatic processes can be goal driven and controlled processes are just as determined as automatic ones (Bargh and other social psychs)

7. Dual system theories (e.g. Reber, Epstein, Evans & Over, Stanovich) SYSTEM 1SYSTEM 2 Evolutionarily oldEvolutionarily recent Shared with animalsUnique to humans UnconsciousConscious AutomaticControlled Low effortHigh effort RapidSlow Contextualised/ domain- specific Abstract / domain-general Default respondingInhibition, intervention Independent of IQ and WMDependent on IQ and WM

8. Problems with dual systems 1. Evolutionary and human/animal distinction If System 2 evolved late and uniquely in humans, then why do animals have working memory and higher order control systems (Toates)? Unique features of human cognition seem to depend on language, theory of mind and meta- representation. But these appear to be modular and automatic, and hence belong to System 1 Belief bias – a classic System 1 process – has been shown to originate in the prefrontal cortex, a recently evolved brain area (Goel)

9. Problems with dual systems 2. Contextual dependency A key assumption in dual system theory (c. 2000) was that System 1 was contextualised by belief and prior knowledge whereas System 2 was abstract and logical It has now become apparent that beliefs often influence reasoning in an explicit manner through working memory Children develop belief based reasoning Lower ability samples show correlation between intelligence and belief-based reasoning Current theories of belief effects in reasoning have both implicit and explicit components (Verschueren, Klauer, Evans & Handley)

10. Problems with dual systems 3. Working memory and individual differences System 2 is assumed selectively to involve working memory. Correlations with cognitive capacity measures are often regarded as diagnostic of System 2 function (Stanovich) as is disruption by concurrent working memory load (De Neys) But lack of correlation cannot exclude System 2, as tasks may simply make light demands on WM Also, the list of cognitive functions that correlate with WMC is vast, including implicit forms of learning Working memory cannot be a single system that does all of these things on its own. We might as well attribute them all to the ‘conscious mind’

11. Interim conclusions Neither System 1 nor System 2 can be single systems. Stanovich (2004) describes S1 as TASS (the set of autonomous subsystems), but Stanovich (2009) sees only the need to partition S2 into the algorithmic and reflective minds ‘System 2’ functions cannot be attributed only to type 2 processes that involve WM. Type 1 processing is involved in all cognitive acts that are attributed to S2 (attention, language and pragmatic processing, retrieval of relevant knowledge from long-term memory etc). How to reconcile these problems with the mass of evidence for dual processing?

12. Type 1 and 2 systems Samuels (2009) argues that there are multiple systems in the brain and it makes no sense to talk of Systems 1 and 2 He suggests a distinction between type 1 and 2 systems that have the usual characteristics (fast, automatic vs slow, controlled etc) However, Samuels offers no psychological theory of this or any architectural basis for the distinction The obvious (to me) criterion should be that a type 2 system requires WM and a type 1 system does not

13. Type 1 systems Cognitive modules (Fodor, 1983) qualify as type 1 systems. Examples: visual system, language acquisition device, theory of mind module. Such modules are isolated and encapsulated and independent of WMC and may be innate Many recent authors have argued for a weaker definition of modularity (e.g. Sperber, Barrett, Carruthers). E.g., Sperber says the English language is an acquired module. Carruthers that modules need not be isolated and can interrogate each other Implicit and explicit memory systems are also type 1 as they store and retrieve knowledge by hidden, dedicated processes. However, explicit memories can be made available to WM for type 2 processing

14. Autonomous vs support systems Type 1 systems need to be divided into those that control behaviour directly and those that provide representations for type 2 processing E.g. the dorsal visual system is autonomous while the ventral visual system is a support system Similarly, habit and procedural learning are autonomous, but the hippocampal memory system is support. Needs WM to affect behaviour. Some T1 systems may seem to do both, e..g language module directly involved in speech production but may also pass representations into WM. Probably bifurcated like the visual system

15. Autonomous vs support systems Autonomous T1 systems Dorsal visual system Habit learning Motor skills … Support T1 systems Ventral visual system Hippocampal memory Pragmatic processing … Behaviour Working Memory Type 2 processing

16. Type 2 systems There can be no unique System 2 that does reasoning, decision making, planning, reading, learning and all the other things that involve WM. Neural-imaging studies of higher cognitive functions such as reasoning and executive function implicate many brain areas that differ greatly from study to study But all type 2 functions share some common features such as being relative slow, sequential, capacity limited and (in some sense) ‘intentional’. We can make sense of this by requiring all type 2 systems to compete for a single WM resource. This also means that only one type 2 system can function at a time, whereas many type 1 systems can operate in parallel Belief in System 2 is due to folk psychology

17. The set of type 2 systems WM Cognitive component

18. Type 2 systems – ad hoc committees? T2 systems seem to function as ad hoc committees, with just those members required to perform a given task T2 systems are many and varied. There is no singular system for reasoning, for example, hence the confusing pattern of neural imaging studies WM is always a member, but that is not to say that it chairs the committee. I don’t really believe in a ‘central executive’

19. Type 1 systems sit on Type 2 committees? What are the ‘cognitive components’ other than WM that make up a type 2 system? Surely they are support type 1 systems as previously defined E.g. a T2 system for reading must involve vision, specialised pattern recognition systems, language modules, pragmatic systems, long-term memory retrieval etc, all of which are type 1 systems A T2 system for reasoning would involve all of the above but requires some additional members for rule processing etc

20. Does this imply a massively modular architecture? Yes and no. It has something in common with soft MMT (like Sperber and Carruthers), in which modules are nothing much more than cognitive components However, I disagree with Carruthers who treats working memory and S2 processing as virtual – the emergent properties of modules Sperber attributes higher functions to modules but clearly fails to make a type 1 and 2 distinction There is something special and distinctive about working memory and type 2 systems

21. Is this compatible with the two minds hypothesis? Yes. The mistake in dual system theory is to conceive of System 2 as (a) a singular system and (b) one that is comprised entirely of type 2 processing We can have an old mind which is animal-like and comprised of autonomous type 1 systems We can have a new mind which formulates type 2 systems by combining support type 1 systems with WM Note that the recently evolved and distinctively human ‘modules’ like language and theory of mind are key support systems for type 2 processing

22. Cognitive control – the big mystery Many dual system theorists overload System 2 with cognitive control. Control must be preconscious and preattentive Some mechanism must exist for allocating WM resources. WM is always active but the function of type 2 processing is constantly changing according to which current task or goal has priority. WM does not choose its own function (or we are back to folk psychology and the conscious mind) Behaviour is controlled largely by autonomous systems but with some type 2 intervention. By what mechanism is this control decided?

23. Complex systems – a partial solution Many complex systems exist whose properties emerge from numerous interactions of small units, e.g. ecosystems, economics systems There is a large amount of research into such systems using computer modelling Macro-economics arises from millions of local economic interactions between individual agents The internet has no central control, only a set of local rules for immediate interactions However, we seem to have two minds – autonomous and executive – both of which are complex systems. Yet behaviour is (mostly) smoothly co-ordinated

24. Confabulation and folk psychology The executive mind builds an illusion (the conscious self) that it is in conscious control of behaviour A key support system – theory of mind – is turned inward to interpret our own behaviour (see also Carruthers) Hence, self-interpretation is a type 2 system Cognitive control and achievement of short, medium and long-term goals, must be an emergent property of the interaction of autonomous and executive minds, into which we have no self- insight at all