How do we use computational models of cognitive processes? Tom Stafford Department of Psychology University of Sheffield Redwood Center, UC Berkeley, 19th March 2010 Application of computational and systems neuroscience models to acting and action-learning Stafford, T. & Gurney, K.N. (2007), Biologically constrained action selection improves cognitive control in a model of the Stroop task, Phil.Trans. of the Royal Society B:, 362 (1485), 1671-1684. A reintepretation of BG functional anatomy Gurney, K., Prescott, T. J., & Redgrave, P. (2001). A computational model of action selection in the basal ganglia. I. A new functional anatomy. Biological cybernetics, 84(6), 401–410. Against the RPE hypothesis of DA function Redgrave, P. G., & Gurney, K. (2006). The short-latency dopamine signal: a role in discovering novel actions? Nature Reviews Neuroscience, 7(12), 967. What algorithms can discover, and store for re-use, novel actions? EU FP7 Funding : 'Intrinsically Motivated Cumulative Learning in Versatile Robots' (Principal: Gianluca Baldassarre, ISTCCNR, Rome) How do we use computational models of cognitive processes? Tom Stafford Department of Psychology University of Sheffield Redwood Center, UC Berkeley, 19th March 2010 What is the point of computational modelling? “...A rather low brow enterprise” (Crick, 1989) Models cannot tell us anything about the world... nor can they provide new information about brain organisation or function (Segalowtiz & Bernstein, 1997) F. Crick, The recent excitement about neural networks. Nature 337, 129 (1989). S. Segalowitz and D. Bernstein, Neural networks and neuroscience: What are connectionist simulations good for, in The future of the cognitive revolution., (Oxford University Press, 1997) Tritonia = a kind of marine mollusc A scheme for categorising the purposes of computational modelling (Stafford, 2009) Stafford, T. (2009). What use are computational models of cognitive processes? In J. Mayor, N. Ruh & K. Plunkett (eds.) Connectionist Models of Behavior and Cognition II: Proceedings of the 11th Neural Computation and Psychology Workshop (pp 265-274). World Scientific. Three claims: 1. There are many purposes for which you might build a computational model 2. You should say which of these motivates your model building 3. The best kind of reasons are those relating to explanations: using correspondences between model parts to make or test predictions which bear on real-world entities Assumption: modelling as a kind of theory construction Model purposes (Stafford, 2009) Exploratory capacity data fitting biological plausibility reinterpretation problem definition Analysis Integration Explanation Understanding explanation using the “modelling is just tautology” accusation (Stafford, 2009) 1+2=3 Model purposes (Stafford, 2009) Exploratory capacity data fitting biological plausibility reinterpretation problem definition Analysis Integration Explanation prediction testing sufficiency existence proof insufficiency Understanding explanation using the “modelling is just tautology” accusation 1+2=3 “Models aid explanation in the same way as mathematics: by enhancing our perception beyond the horizon of individual reason and intuition” An empirical investigation into how modelling work is presented to the scientific community Aims: 1. Test of the framework proposed by Stafford(2009) 2. Discover what makes modelling work accessible to the non-modelling community of experimentalists/theorists An empirical investigation into how modelling work is presented to the scientific community Objectives: 1. Test if and how this scheme applies to successful (i.e. highly cited) modelling papers 2. Identify practices associated with highcitation rates http://experimentalphilosophy.typepad.com/ http://x-phi.org/ Corpus: Web of Science searches, sorted by most highly cited for: 1. Neural Computation 2. Connection Science 3. Publication Name=(nature) AND Topic=(computational) AND Topic=(neuroscience OR psychology) 4. Publication Name=(nature neuroscience) AND Topic=(computational) 5. Publication Name=(cognitive science) AND Topic=(model) and Papers from the 11th NCPW Conference Most highly cited papers in selected journals Question 1: Is making explicit your purpose for building a model associated with publication in quality journals and/or higher citation counts? Assumption: Because you can build models for lots of different reasons, if you don't say why you are building a model it cannot be as easily assessed or used by the non-modelling community Mostly, but not always, highly cited papers are explicit about the purpose of model building Mean citations not higher for papers which make explicit their purpose (probably) Question 2: What purposes are associated with highly cited papers? Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency A good fit is not enough Roberts & Pashler (2000) How Persuasive is a good fit: a Comment on Theory Testing. Psychological Review, 107(2), 358-367. Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Exploratory Nat Conn. Nature Neuro Cog Sci Sci Capacity 2 5 4 18 Data fitting 0 1 6 0 Biol. plausibility 0 0 1 2 Reinterpretation 1 0 1 0 Problem-definition 0 0 1 1 Neural NCPW1 Comp 1 22 17 0 6 0 5 0 2 0 0 TOTAL 68 13 8 4 2 95 Analysis 2 1 2 0 0 2 7 7 Integrative 1 5 5 7 3 6 27 27 1 0 2 0 1 4 0 7 2 0 3 6 3 0 0 1 2 3 0 2 1 0 0 0 0 3 1 2 0 0 13 9 17 2 3 44 Explanatory prediction testing sufficiency existence proof insufficiency Conclusions 1. Most models are built for exploratory rather than explanatory purposes 2. Highly cited modelling papers are built for a diversity of reasons 3. Importance of modelling for providing theory integration and novel frameworks unanticipated by Stafford (2009) 4. Importance of modelling providing new methods/techniques unanticipated by Stafford (2009) Better quality journals have higher (but still <0.5) proportion of 'explanatory' models “Advice to the young modeller”? Anything goes? Improvements to the method Double, blind, rating of papers Analysis of modelling papers cited outside of modelling journals (i.e. by experimentalists) Analysis of papers which combine modelling and experimental work from the same lab Analysis of modelling papers which built on / test existing models THE END t.stafford@shef.ac.uk “The [theorist] will endeavor not to show us a commonplace photograph of life, but to give us a presentment of it which shall be more complete, more striking, more cogent than reality itself. To tell everything is out of the question; it would require at least a volume for each day to enumerate the endless insignificant incidents which crowd our existence. A choice must be made—and this is the first blow to the theory of ‘the whole truth’.” - Guy de Maupassant "I also suspect that within most modellers a frustrated mathematician is trying to unfold his wings. It is not enough to make something that works. How much better if it can be shown to embody some powerful general principle for handling information, expressible in a deep mathematical form, if only to give an air of intellectual respectability to an otherwise rather low-brow enterprise.” - Crick (1989) “The recent excitement about neural networks” Nature, 337, 129-132