Discovering rules unconsciously

Dijksterhuis and Nordgren put forward a theory of unconscious thought. They propose that there are two types of thought process: conscious and unconscious. “CT (conscious thought) refers to object-relevant or task-relevant cognitive or affective thought processes that occur while the object or task is the focus of one’s conscious attention, whereas UT (unconscious thought) refers to object-relevant or task-relevant cognitive or affective thought processes that occur while conscious attention is directed elsewhere.’’

Like Kahneman’s System 1 and System 2 thought there is no implication here that there is purely conscious thought with no unconscious components but only that conscious awareness is part of the process. I prefer the System name as it avoids the possible interpretation that there might be purely conscious thought. System 1 is like UT and is characterized as: autonomous, fast, effortless, hidden/unconscious, simultaneous/parallel/complex. System 2 is like CT: deliberate, slow, effortful, conscious, serial/logical/simple. The most telling difference is whether working memory is used; working memory restricts the number of items that can be manipulated in thought to about 7 or less at a time and introduces the conscious awareness of the working memory. It is often viewed as a difference between calculation and estimation, or between explicit and implicit knowledge.

The way these two processes are compared is to set out a problem and then compare the results after one of three activities: the subjects can consciously think about the problem for a certain length of time; the subjects can spend the same amount of time doing something that completely engages their consciousness; or they can be giving no time at all and asked for the answer immediately after the problem is presented. It has been found that with complex problems with many ingredients, that System 1/UT gives more quality results then System 2/CT and both are better than immediate answers.

A recent paper by Li, Zhu and Yang looks at another comparison of the two ways of thinking. (citation below)


According to unconscious thought theory (UTT), unconscious thought is more adept at complex decision-making than is conscious thought. Related research has mainly focused on the complexity of decision-making tasks as determined by the amount of information provided. However, the complexity of the rules generating this information also influences decision making. Therefore, we examined whether unconscious thought facilitates the detection of rules during a complex decision-making task. Participants were presented with two types of letter strings. One type matched a grammatical rule, while the other did not. Participants were then divided into three groups according to whether they made decisions using conscious thought, unconscious thought, or immediate decision. The results demonstrated that the unconscious thought group was more accurate in identifying letter strings that conformed to the grammatical rule than were the conscious thought and immediate decision groups. Moreover, performance of the conscious thought and immediate decision groups was similar. We conclude that unconscious thought facilitates the detection of complex rules, which is consistent with UTT.

It is a characteristic of System 2/CT that it is used to rigorously follow rules to calculate a result. However there is a difference between following a rule and discovering one. This rule discovery activity may be the same as implicit learning. “Mealor and Dienes (2012) combined UT and implicit learning research paradigms to investigate the impact of UT on artificial grammar learning. A classic implicit learning paradigm consists of two stages: training and testing. ” The UT group had better results but they categorized the process as random selection. The current paper shows that the UT group can find the grammatical rules illustrated in the training and then identify grammatical as opposed to ungrammatical strings. System 1/UT is better at uncovering rules and of identifying examples that break the rules. This does not seem to be a rigorous following of rules as in System 2 but more a statistical tendency or a stereotypical categorization of the nature of implicit learning.

It is important to be clear that System 2 or CT is thought that has a conscious component and it does not imply that the thought is conducted ‘in’ consciousness. We are aware of the steps in a train of thought, but not aware of the process, they are hidden.

Li, J., Zhu, Y., & Yang, Y. (2014). The Merits of Unconscious Thought in Rule Detection PLoS ONE, 9 (8) DOI: 10.1371/journal.pone.0106557

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3 thoughts on “Discovering rules unconsciously

  1. Sergio Graziosi

    Interesting summary, and I haven’t read the papers yet, so apologies for the somewhat uninformed questions/remarks. The way you describe the results/discussion of Li et al. and Mealor and Dienes is that people where somehow able to learn artificial grammar rules without engaging System 2/CT, and if that’s the case I’d be very surprised.
    Looking at the Mealor and Dienes abstract, it seems that the paradigm is different: it’s about letting/not letting the information absorbed via conscious attention to be further processed unconsciously before testing how well the information has been learned, and their results do not surprise me at all.
    Also: S1/UT is what we use to perform tasks that we are proficient with (think of driving along the usual route) making me think that the last part of your post is more about effective learning, the acquisition of fast, maybe heuristic ways to evaluate and react to a given complex stimulus. In this interpretation, it’s no surprise that a period of “distraction” after conscious learning helps becoming more proficient.
    The difference may be subtle, but it’s of paramount importance for a project of mine: I rest on the assumption that learning complex rules/behaviours requires to start by engaging S2/CT…

    1. JKwasniak Post author

      Thank you for the comment. All three groups were given a training session where they were shown in a fairly rapid fashion a series of examples of ‘grammatical’ groups of coloured letters and digits. Immediately after the training, one group was tested. The other two groups were tested after a period of time in which one group tried consciously to figure of the rule that made the training set all ‘grammatical’ and the other group had their consciousness forced to do a memory test that used the working memory for the whole time. They could only think about the ‘rule’ unconsciously. As the immediate and the 2/CT groups were no better than chance when they were tested at identifying grammatical examples, neither group discovered the rule during the training session and the 1/CT did not find it during their conscious attempt after training. The 1/UT group did significantly better on the test. It is my impression (from other writing) that the 1/UT group did not articulate the rule but simply did very well at identifying the good examples while they thought they were using more or less random hunches. In other words, the extent to which they understood the rule was in implicit memory (by implicit learning) and not explicit. They did not consciously know what they unconsciously could show they knew. This is like the implicit knowledge of experts (nurses, radiologist for example) who learn pattern recognition thought practice, are extremely quick and accurate, but cannot say how they spot the abnormalities that ‘pop out’ at them. Or I my experience, I see a bird for the first time and I call it a duck or I see a plant and I call it a clover. It do not consciously know the rules that make a bird a duck or a plant a clover. I would have to think for a long time to make a list of what is duck like and what is clover like. But implicitly I know. If you define ‘rule’ as a logical statement, than it probably has to be in explicit memory but if it is a pattern that is associative or stereotypical than it can be in implicit memory. Now, you can say that the ducks and clovers that I have seen and been aware of consciously are important for the process but I never consciously encountered the ‘rules’ of what makes a duck or a clover, and I did not think about them consciously. I knew consciously that ducks had web feet, feathers and liked water but that could apply to many types of birds. I am aware of what I encountered and thought in 2/CT but I have no knowledge of what I encountered or thought in 1/UT. The real pattern recognition is just not available to me consciously. In the situation in the paper, it is the unconscious processing after the conscious exposure during training that finds the patterns and therefore the rule in an implicit form. There is no way to tell whether the training only used 2/CT – it may also have been taking in the information using 1/UT. I would guess it was both but have no evidence for that.

      1. Sergio Graziosi

        Thank you!
        This is the second time I’ve unwillingly made you do my own homework, I should be more careful in the future.
        On the specific: I think these studies are zooming into a very interesting and difficult to navigate area (implicit vs. explicit learning/pattern recognition). It’s hard to say what these results mean for my own little project, but for now I’m happy to accept that the training did require some 2/CT, even if the real learning may indeed be exclusively 1/UT. Will keep an eye on the developments…
        Thanks again,


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