Is Cognitive Psychology Doomed to Failure ?

1. Is Cognitive Psychology Doomed to Failure ? Vaughan Bell vaughan@backspace.org

2. Outline • Aims and assumptions of cognitive psychology • Scientific methodology • Information processing view of the mind • Criticisms from: • Phenomenology • Algorithmic information theory • Future directions ?

3. Scientific / Positivist Approach • Cognitive psychology has inherited experimentalmethodology from behaviourism. • It is also positivist and reductionist, assuming that mental phenomena can be measured and fractionated. • And although entertains ideas of mentalstates, has largely rejected the introspective methods and subjectivity of Freud.

4. Information Processing • To varying degrees, cognitive psychology seeks to explain the mind in terms of information processing. • Pylyshyn (1979, p435) argues that “computation is not a metaphor but part of a literal description of cognitive activity”. • Parkin (2000) argues that cognitive psychologists use information processing purely as an analogy for mental function.

5. Has this become a dogma ? • Still and Costall (1987) would agree and have argued that cognitive psychology has become “restrictive as well as complacent”. • Even Don Norman (1981) has criticized cognitive psychology for “sterility” and for descriptions which “do not fit actual behaviour”. • I am going to look at criticisms from two sources: Phenomenology and Algorithmic Information Theory

6. Phenomenology • Originated with Husserl and continued by the likes of Heidegger, Satre and Merleau-Ponty. Martin Heidegger (1889 – 1976) Edmund Hussrl (1859 - 1938)

7. Core Beliefs • Phenomenology seeks to describe the structures of experience as they present themselves to consciousness. • Without recourse to theory, deduction, or assumptions from other disciplines. • Two of the main objections by phenomenologists to cognitive psychology are quantification and abstraction of human experience.

8. Objections to Quantification • Phenomenologists believe that human experience cannot be quantified without stripping it of all meaning. • They argue experience cannot be reduced to its component parts. • And by doing so, we are throwing the baby out with the bath water... • ...choosing a quest for scientific respectability over the truth of human experience.

9. Objections to Abstraction • Similarly they stress the importance of intentionality and situated action (being-in-the-world). • This implies that our thoughts cannot be meaningfully separated from the environment with which they interact. • And by studying psychology in artificial experimental situations we will get nothing except an artificial understanding of the mind.

10. Information Processing • Algorithmic and information processing models are ubiquitous in modern psychology. • Philosophers (e.g. Searle) argue that psychology cannot be fully described by computation. • Many psychologists would agree, however I can think of very few cognitive models that could not in principle by implemented computationally.

11. Innate Problems with Computation • Two mathematicians have been particularly important in showing the limits of computation. Kurt Gödel (1906 – 1978) Alan Turing (1912 – 1954)

12. Gödel’s Incompleteness Theorem • Much to the surprise of the mathematical world, Gödel discovered in 1930 that: • i. in any consistent system of mathematics, one can construct a statement about natural numbers that can be neither proven nor disproven within that system • ii. any such system cannot prove its own consistency

13. Halting Problem and Completeness • Turing discovered there is no way to calculate a priori, whether any given algorithm will complete or not. • In other words, there are some things with are just not computable. • He also described the minimum operations a computer needs to compute. • A system that is Turing-complete can execute any possible computer programme.

14. Minimal Example • Brainfuck is a programming language designed by Urban Müller (1993) to be the smallest Turing-complete language. • It has 8 single character instructions. Every possible computer programme can be rewritten in it. • ++++++++++[>+++++++>++++++++++>+++>+<<<<-] >++.>+.+++++++..+++.>++.<<+++++++++++++++. >.+++.------.--------.>+.>. • The ‘Hello world’ programme.

15. Relevance to Cognitive Science • If we accept the information processing model: • Gödel: There may be some mental states we will never uncover, and we cannot verify cognitive theories without referring to non-cognitive ones. • Turing:A priori, cognitive systems will be unable to solve certain problems. • Müller: All other mental functions can be coded into strings made from only eight characters.

16. Future Directions I • We seem to need an idea of where information processing models are inappropriate. • Past success is not always a good measure of appropriateness. • Because we may be using the right model in the wrong way, or using it to ask the wrong questions. • i.e. Difficult problems have difficult to conceive answers.

17. Future Directions II • Perhaps we can look at previous examples of hybrid or non-cognitive models (e.g. Gibson, Bartlett) • Or take inspiration from neurobiology, philosophy, computer science, art etc and hope that we can muddle through. • Although we may have to accept parallel models and the waxing and waning of academic fashions.