Peer Review of Pothos's 'The Rules Versus Similarity Distinction'
Source: Behavioral and Brain Sciences, 28, Issue 01, February 2005, pp 15-36
Paper - Abstract

Paper SummaryText Colour-Conventions


  1. Similarity in logical reasoning and decision-making
    • Horacio Arló-Costa, Department of Philosophy, Carnegie Mellon University, Pittsburgh, PA 15213,
    • Abstract: Normative accounts in terms of similarity can be deployed in order to provide semantics for systems of context-free default rules and other sophisticated conditionals. In contrast, procedural accounts of decision in terms of similarity (Rubinstein 1997) are hard to reconcile with the normative rules of rationality used in decision-making, even when suitably weakened.
  2. Empirical dissociations between rule-based and similarity-based categorization
    • Gregory Ashby and Michael B. Casale,(Department of Psychology, University of California, Santa Barbara, CA 93106, .
    • Abstract: The target article postulates that rule-based and similarity-based categorization are best described by a unitary process. A number of recent empirical dissociations between rule-based and similarity-based categorization severely challenge this view. Collectively, these new results provide strong evidence that these two types of category learning are mediated by separate systems.
  3. Rules work on one representation; similarity compares two representations
    • Todd M. Bailey, School of Psychology, Cardiff University, Cardiff CF10 3YB, United Kingdom, .
    • Abstract: Rules and similarity refer to qualitatively different processes. The classification of a stimulus by rules involves abstract and usually domain-specific knowledge operating primarily on the target representation. In contrast, similarity is a relation between the target representation and another representation of the same type. It is also useful to distinguish associationist processes as a third type of cognitive process.
  4. Instantiated rules and abstract analogy: Not a continuum of similarity
    • Lee R. Brooks and Samuel D. Hannah, Department of Psychology, McMaster University, Hamilton, Ontario, L8S 4K1, Canada.
    • Abstract: We agree that treating rules and similarity as dichotomous opposites is unproductive. However, describing all categorization operations as a continuum of varied similarity process obscures a multidimensional contrast. We describe two processes, instantiated rules and abstract analogy, both of which have aspects of rules and similarity, and question whether they can be compared informatively as points on a continuum.
  5. Rules, similarity, and the information-processing blind alley
    • Francisco Calvo Garzón, Department of Philosophy, University of Murcia, Campus de Espinardo, Murcia 30100, Spain,
    • Abstract: Pothos's revision of rules and similarity in the area of language illustrates the impression that the classicist/connectionist debate is in a blind alley. Under his continuum proposal, both hypotheses fall neatly within the information-processing paradigm. In my view, the paradigm shift that dynamic systems theory represents (Spencer & Thelen 2003) should be submitted to critical scrutiny. Specific formalizations of the Rules versus Similarity distinction may not lead to a form of unification under Generalized Context Models or connectionist networks.
  6. Epistemological requirements for a cognitive psychology of real people
      John Campion, Bembrook Cottage, Woodmans Green, Linch, Liphook, Hants GU30 7NE, United Kingdom.
    • Abstract: Pothos's analysis is difficult to relate to real human mental processes. He tackles four quite different areas of psychology and adduces evidence from a large number of paradigms. Yet despite this very large scope, he employs a single, simplistic descriptive framework. An epistemological analysis, supported by illustrations from real world decision-making, shows that this steers us away from, rather than towards, an understanding of real human cognitive processes.
  7. Real rules are conscious
    • Axel Cleeremans and Arnaud Destrebecqz, Cognitive Science Research Unit, Université Libre de Bruxelles, Fonds National de la Recherche Scientifique, B-1050, Belgium, Link.
    • Abstract: In general, we agree with Pothos's claim that similarity and rule knowledge are best viewed as situated on the extreme points of a single representational continuum. However, we contend that a distinction can be made between “rule-like” and “rule-based” knowledge: Rule-based, symbolic knowledge is necessarily conscious when it is applied. Awareness thus provides a useful criterion for distinguishing between sensitivity to functional similarity and knowledge of symbolic rules.
  8. Two types of thought: Evidence from aphasia
    • Jules Davidoff, Department of Psychology, Goldsmiths' University of London, Goldsmiths' College, London SE14 6NW, United Kingdom.
    • Abstract: Evidence from aphasia is considered that leads to a distinction between abstract and concrete thought processes and hence for a distinction between rules and similarity. It is argued that perceptual classification is inherently a rule-following procedure and these rules are unable to be followed when a patient has difficulty with name comprehension and retrieval.
  9. “Commitment” distinguishes between rules and similarity: A developmental perspective
    • Gil Diesendruck, Department of Psychology and Gonda Brain Research Center, Bar-Ilan University, Ramat-Gan, 52900, Israel, Link.
    • Abstract: A qualitative difference between Rules and Similarity in categorization can be described in terms of “commitment”: Rules entail it, Similarity does not. Commitment derives from people's knowledge of a domain, and it is what justifies people's inferences, selective attention, and dismissal of irrelevant information. Studies show that when children have knowledge, they manifest these aspects of commitment, thus overcoming Similarity.
  10. The discontinuity between rules and similarity
    • Peter F. Dominey, Institut des Sciences Cognitives, 69675 BRON Cedex, France,
    • Abstract: In arguing for a rules-similarity continuum, Pothos should demonstrate that a single process or mechanism (a neural network model, for example) can handle the entire continuum. Pothos deliberately avoids this exercise as beyond the scope of the current research. In this context, I will present simulation, neuropsychological, neurophysiological, and experimental psychological results, arguing against the continuity hypothesis.
  11. Rules, similarity, and threshold logic
    • Wlodzislaw Duch, Department of Informatics, Nicholaus Copernicus University, 87100 Torun, Poland; School of Computer Engineering, Nanyang Technological University, 639798 Singapore, Link.
    • Abstract: Rules and similarity are two sides of the same phenomenon, but the number of features has nothing to do with transition from similarity to rules; threshold logic helps to understand why.
  12. Rules and similarity as conscious contents with distinctive roles in theory
    • Donelson E. Dulany, Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL 61821,
    • Abstract: Difficulty of distinguishing rules and similarity in categorization comes from reliance on relatively simple manipulation-response designs and a style of modeling with abstract parameters, rather than assessment of intervening and controlling mental states. This commentary proposes a strategy in which rules and similarity would be distinguished by their different roles in a theory interrelating reportable conscious contents in deliberative categorization.
  13. Is this what the debate on rules was about?
    • Ulrike Hahn, School of Psychology, Cardiff University, Cardiff CF10 3YG, United Kingdom, .
    • Abstract: The key weakness of the proposed distinction between rules and similarity is that it effectively converts what was previously seen as a consequence of rule or similarity-based processing, into a definition of rule and similarity themselves – evidence is elevated into a conceptual distinction. This conflicts with fundamental intuitions about processes and erodes the relevance of the debate across cognitive science.
  14. Rules and similarity – a false dichotomy
    • James A. Hampton, Psychology Department, City University, Northampton Square, London EC1V OHB, United Kingdom, Link.
    • Abstract: Unless restricted to explicitly held, sharable beliefs that control and justify a person's behavior, the notion of a rule has little value as an explanatory concept. Similarity-based processing is a general characteristic of the mind-world interface where internal processes (including explicitly represented rules) act on the external world. The distinction between rules and similarity is therefore misconceived.
  15. Illuminating reasoning and categorization
    • Evan Heit (Department of Psychology, University of Warwick, Coventry CV4 7AL, United Kingdom, Link) and Brett K. Hayes (School of Psychology, University of New South Wales, Sydney NSW 2052, Australia, ).
    • Abstract: The proposal regarding rules and similarity is considered in terms of ability to provide insights regarding previous work on reasoning and categorization. For reasoning, the issue is the relation between this proposal and one-process as well as two-process accounts of deduction and induction. For categorization, the issue is how the proposal would simultaneously explain both similarity-to-rule and rule-to-similarity shifts.
  16. Processing is shaped by multiple tasks: There is more to rules and similarity than Rules-to-Similarity
    • Gary Lupyan and Gautam Vallabha (Department of Psychology and the Center for the Neural Basis of Cognition, Carnegie Mellon University, Pittsburgh, PA 15213, +W1196W).
    • Abstract: We argue that the Rules-Similarity continuum is only a useful formalism for particular, isolated tasks and must rest on the assumption that representations formed during a particular task are independent of other tasks. We show this to be an unrealistic conjecture. We additionally point out that describing categorization as selective weighing and abstracting of features misses the important step of discovering what the possible features are.
  17. Opposites detract: Why rules and similarity should not be viewed as opposite ends of a continuum
    • Gary Marcus (Department of Psychology, New York University, New York, NY 10012, ).
    • Abstract: Criteria that aim to dichotomize cognition into rules and similarity are destined to fail because rules and similarity are not in genuine conflict. It is possible for a given cognitive domain to exploit rules without similarity, similarity without rules, or both (rules and similarity) at the same time.
  18. Digging beneath Rules and Similarity
    • Arthur B. Markma, Sergey Blo, Kyungil Ki, Levi Larke, Lisa R. Narvae, C. Hunt Stilwell and Eric Taylor (Department of Psychology, University of Texas, Austin, TX 78712, Link).
    • Abstract: Pothos suggests dispensing with the distinction between rules and similarity, without defining what is meant by either term. We agree that there are problems with the distinction between rules and similarity, but believe these will be solved only by exploring the representations and processes underlying cases purported to involve rules and similarity.
  19. It's not how many dimensions you have, it's what you do with them: Evidence from speech perception
    • Bob McMurray (Department of Psychology, University of Iowa, Iowa City, IA 52242) and David Gow (Neuropsychology Laboratory, Massachusetts General Hospital, Boston, MA 02114).
    • Abstract: Contrary to Pothos, rule- and similarity-based processes cannot be distinguished by dimensionality. Rather, one must consider the goal of the processing: what the system will do with the resulting representations. Research on speech perception demonstrates that the degree to which speech categories are gradient (or similarity-based) is a function of the utility of within-category variation for further processing.
  20. Rule versus similarity: Different in processing mode, not in representations
    • Rolf Reber (Department of Psychosocial Science, University of Bergen, N-5015 Bergen, Norway, ).
    • Abstract: Drawing on an example from artificial grammar learning, I present the case that similarity processes can be computationally identical to rules processes, but that participants in an artificial grammar learning experiment may use different processing modes to classify stimuli. The number of properties and other representational differences between rule and similarity processes are an accidental consequence of strategies used.
  21. Rules and similarity processes in artificial grammar and natural second language learning: What is the “default”?
    • Peter Robinson (Department of English, Aoyama Gakuin University, 4-4-25 Shibuya, Shibuya-ku, Tokyo 150-8366, Japan, Link).
    • Abstract: Are rules processes or similarity processes the default for acquisition of grammatical knowledge during natural second language acquisition? Whereas Pothos argues similarity processes are the default in the many areas he reviews, including artificial grammar learning and first language development, I suggest, citing evidence, that in second language acquisition of grammatical morphology “rules processes” may be the default.
  22. Avoiding foolish consistency
    • Steven Sloman (Department of Cognitive and Linguistic Sciences, Brown University, Providence, RI 02912, Link).
    • Abstract: In most cases, rule-governed relations and similarity relations can indeed be distinguished by the number of relevant features they require. This criterion is not sufficient, however, to explain other properties of the relations that have a more dichotomous character. I focus on the differential drive for consistency by inferential processes that draw on the two types of relations.
  23. Rule and similarity as prototype concepts
    • Edward E. Smith (Department of Psychology, University of Michigan, Ann Arbor, MI 48109-1109).
    • Abstract: There is a continuum between prototypical cases of rule use and prototypical cases of similarity use. A prototypical rule: (1) is explicitly represented, (2) can be verbalized, and (3) requires that the user selectively attend to a few features of the object, while ignoring the others. Prototypical similarity-use requires that: (1) the user should match the object to a mental representation holistically, and (2) there should be no selective attention or inhibition. Neural evidence supports prototypical rule-use. Most models of categorization fall between the two prototypes.
  24. In search of radical similarity
    • Oscar Vilarroya (Unitat de Recerca en Neurociència Cognitiva, IMPU, Universitat Autònoma de Barcelona, 08035 Barcelona, Spain).
    • Abstract: It is difficult to see how one can support the continuum between rules and similarity, as Pothos proposes. A similarity theory could dispense with the rules end of the continuum. The only thing that we need is one (or more than one) theory of similarity that goes beyond the stimulus-carrying information and behavioristic restrictions that have usually been attributed to similarity theories.
  25. Integration of “rules” and “similarity” in a framework of information compression by multiple alignment, unification, and search
    • J. Gerard Wolff (Cognition Research, Menai Bridge, Anglesey, LL59 5LR, United Kingdom, Link).
    • Abstract: The Simplicity and Power (SP) theory (Wolff 2003a) provides support for Pothos's proposals by illustrating how the effect of “rules” and “similarity” may be achieved within an integrated model that makes no explicit provision for either concept. The theory is described here in outline with simple examples to show how rules and similarity can emerge as properties of the system in learning, reasoning, categorization, and the parsing of language.


Peer review of "Pothos (Emmanuel M.) - The Rules versus Similarity Distinction".

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  1. Blue: Text by me; © Theo Todman, 2018
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