Optimization and simplicity: Computational vision and biological explanation

David Marr's theory of vision has been a rich source of inspiration, fascination and confusion. I will suggest that some of this confusion can be traced to discrepancies between the way Marr developed his theory in practice and the way he suggested such a theory ought to be developed in his explicit metatheoretical remarks. I will address claims that Marr's theory may be seen as an optimizing theory, along with the attendant suggestion that optimizing assumptions may be inappropriate for cognitive mechanisms just as anti-adaptationists have argued they are inappropriate for other physiological mechanisms. I will discuss the nature of optimizing assumptions and theories. Considering various difficulties in identifying and assessing optimizing assumptions, I will suggest that Marr's theory is not purely an optimizing theory and that reaction to Marr on this issue prompts interesting considerations for the development of inter-disciplinary constraints in the cognitive and brain sciences.Thanks are due to Ron McClamrock for his comments on previous drafts of this material. Also, early versions of some of the material in this paper were presented at LMPS '91 and at a Cognitive Studies Colloquium at Penn State University in 1992. Thanks to those in attendance, especially to Rich Carlson and Mark Detweiler, for their comments. Thanks, too, to an anonymous referee for suggesting several useful references.     

Conditional theories

This paper introduces conditional logic, that is, a variant of free logic where the existence condition of a function is defined by a formula of the formal language. Syntax and semantics are developed. A completeness theorem is given.     

Computational psychiatry

Computational ideas pervade many areas of science and have an integrative explanatory role in neuroscience and cognitive science. However, computational depictions of cognitive function have had surprisingly little impact on the way we assess mental illness because diseases of the mind have not been systematically conceptualized in computational terms. Here, we outline goals and nascent efforts in the new field of computational psychiatry, which seeks to characterize mental dysfunction in terms of aberrant computations over multiple scales. We highlight early efforts in this area that employ reinforcement learning and game theoretic frameworks to elucidate decision-making in health and disease. Looking forwards, we emphasize a need for theory development and large-scale computational phenotyping in human subjects.     

Lay theories of rape

This study examined ‘la’ theories of rape and compared them to numerous academic theories. One hundred and thirty subjects-52 male, 78 female-completed two questionnaires, one regarding attitudes/beliefs to rape in general, the other on the possible causes of the crime. Factor analysis revealed five factors in the attitude/belief items: Subjects generally perceived the rape victim as moral, responsible, and unprovoking; the rapist was perceived as a repressed delinquent. Subjects agreed with two of the six explanation factors, seeing rape as resulting from a desire for aggression induced by societal factors. The rapist was believed to be a psychopath. Lay theories did not correspond to any formal academic rape model or explanations. Beliefs about the causes of, and attitudes to rape, correlated highly. Age was the greatest determinant of perspective; older subjects believed more in victim precipitation. Suggestions are made for further research in this comparatively neglected area.     

Privation theories of pain

Most modern writers accept that a privation theory of evil should explicitly account for the evil of pain. But pains are quintessentially real. The evil of pain does not seem to lie in an absence of good. Though many directly take on the challenges this raises, the metaphysics and axiology of their answers is often obscure. In this paper I try to straighten things out. By clarifying and categorizing the possible types of privation views, I explore the ways in which privationists about evil are—or should or could be—privationists about pain’s evil.     

Classifying theories of welfare

This paper argues that we should replace the common classification of theories of welfare into the categories of hedonism, desire theories, and objective list theories. The tripartite classification is objectionable because it is unduly narrow and it is confusing: it excludes theories of welfare that are worthy of discussion, and it obscures important distinctions. In its place, the paper proposes two independent classifications corresponding to a distinction emphasised by Roger Crisp: a four-category classification of enumerative theories (about which items constitute welfare), and a four-category classification of explanatory theories (about why these items constitute welfare).     

Resemblance theories of properties

The paper aims to develop a resemblance theory of properties that technically improves on past versions. The theory is based on a comparative resemblance predicate. In combination with other resources, it solves the various technical problems besetting resemblance nominalism. The paper’s second main aim is to indicate that previously proposed resemblance theories that solve the technical problems, including the comparative theory, are nominalistically unacceptable and have controversial philosophical commitments.     

Patients' theories of pathogenesis

Certain patients embark upon analytic treatment with well thought out theories regarding the origins of their difficulties. Although there is always some validity to such theories, they turn out to be incomplete and serve to screen painful recollections and pathogenic unconscious wishes and the defenses against them. Two cases are presented to illustrate how analysands use these theories in the service of resistance. Painstaking analytic work is required to elucidate their defensive nature. The narcissistic importance of such theories in maintaining a coherent narrative about one's life in the face of uncertainty is discussed, and technical and countertransference considerations are explored.     

Children's theories of motivation

To investigate children’s theories of motivation, we asked 166 children (8-12 years of age) to rate the effect of various motivational strategies on task interest, over the short and long terms, in activities described as appealing or unappealing. Children viewed the rewards strategy as resulting in greatest interest except when implemented over the long term for appealing activities. Individual difference analyses revealed that some children held operant theories of motivation, in which rewards were central, and others held hybrid theories, in which rewards were key, but some allowance was made for interest to be self-sustaining in the absence of inducements. Children’s theories predicted their academic self-regulation. Their theories are discussed relative to an expert theory of motivation.     

Lay theories of willpower

Some people believe that willpower relies on a limited resource and that performing cognitive work (such as using self‐control) results in mental fatigue. Others believe that willpower is nonlimited and that performing cognitive work instead prepares and energizes them for more. These differing lay theories of willpower determine whether or not one's self‐control performance actually does decrease or increase after use, with only limited willpower theorists showing a decrease (the ego depletion effect). Due to the self‐control requirements of everyday life, willpower theories also predict outcomes across domains of academics, health, goal progress, interpersonal relationships, and well‐being. Generally, limited willpower theorists' belief in their limited capacity results in poorer outcomes, particularly during times of high demand. By understanding how willpower theories form and function, interventions that encourage nonlimited willpower theories may be created to improve people's performance and well‐being.     

Lay theories of suicide

The rank order of a set of 32 causal attributes for depression was similar to that for suicide, as judged by a sample of 66 undergraduates.     

The importance of interhemispheric transfer for foveal vision: a factor that has been overlooked in theories of visual word recognition and object perception

In this special issue of Brain and Language, we examine what implications the division between the left and the right brain half has for the recognition of words presented in the center of the visual field. The different articles are a first indication that taking into account the split between the left and the right cerebral hemisphere need not be an inescapable nuisance in models of visual word recognition but may in fact form the clue to the solution of a longstanding problem within this literature. Also, the fact that interhemispheric transfer has implications for foveal word recognition should interest laterality researchers, as it makes their findings more central to normal reading. In this introductory article, I first present a rough picture of the current (lack of) evidence for a bilateral representation of the fovea and the absence of a callosal delay. I then briefly discuss the suggestions made by the different authors on how to integrate the foveal split within current models of visual word recognition.     

Lay theories of delinquency

This paper is concerned with the range, structure and determinants of lay people's implicit theories of delinquency. The different explicit psychological and sociological theories were reviewed as were studies on lay beliefs about crime and delinquency. After pilot interviews in which people were asked to list what they believed to be the major causes of delinquency, over 350 people completed a questionnaire in which they rated 30 explanations for their importance in explaining delinquency. The results showed numerous sex, age and voting differences. Conservatives tended to blame a person's poor education for his or her delinquency, while Labour voters tended to explain delinquency in terms of societal factors. A factor analysis revealed six clear explanation types for delinquency some of which were clearly related to explicit theories. Results were discussed in terms of the psychology of explanations and the relationship between explicit and implicit theories. Implications of this research were also noted.