Representation is representation of similarities

Advanced perceptual systems are faced with the problem of securing a principled (ideally, veridical) relationship between the world and its internal representation. I propose a unified approach to visual representation, addressing the need for superordinate and basic-level categorization and for the identification of specific instances of familiar categories. According to the proposed theory, a shape is represented internally by the responses of a small number of tuned modules, each broadly selective for some reference shape, whose similarity to the stimulus it measures. This amounts to embedding the stimulus in a low-dimensional proximal shape space spanned by the outputs of the active modules. This shape space supports representations of distal shape similarities that are veridical as Shepard's (1968) second-order isomorphisms (i.e., correspondence between distal and proximal similarities among shapes, rather than between distal shapes and their proximal representations). Representation in terms of similarities to reference shapes supports processing (e.g., discrimination) of shapes that are radically different from the reference ones, without the need for the computationally problematic decomposition into parts required by other theories. Furthermore, a general expression for similarity between two stimuli, based on comparisons to reference shapes, can be used to derive models of perceived similarity ranging from continuous, symmetric, and hierarchical ones, as in multidimensional scaling (Shepard 1980), to discrete and nonhierarchical ones, as in the general contrast models (Shepard & Arabie 1979; Tversky 1977).     

Critical NoticeHumanity, Authority and the Mesmeric Ought

Virtues and Reasons: Philippa Foot and Moral Theory , edited by Rosalind Hursthouse, Gavin Lawrence and Warren Quinn     

Competitive learning in biological and artificial neural computation

In this review we will briefly discuss 'classical' competitive learning and approaches to competitive learning that involve mixtures of experts. We will then focus on competitive learning that is guided by the temporal structure that is present within the stimuli. In this context, we will describe a general principle for resource allocation and memory management, that may account for a range of psychophysical and neurophysiological findings.     

Learn locally, act globally: Learning language from variation set cues

Variation set structure - partial overlap of successive utterances in child-directed speech - has been shown to correlate with progress in children’s acquisition of syntax. We demonstrate the benefits of variation set structure directly: in miniature artificial languages, arranging a certain proportion of utterances in a training corpus in variation sets facilitated word and phrase constituent learning in adults. Our findings have implications for understanding the mechanisms of L1 acquisition by children, and for the development of more efficient algorithms for automatic language acquisition, as well as better methods for L2 instruction.     

Demonstrations of a generation effect in context memory

Generation often leads to increased memorability within a laboratory context (see, e.g., Slamecka & Graf, 1978). Of interest in the present study is whether the benefits of generation extend beyond item memory to context memory. To investigate this question, in three experiments, we asked subjects to remember in which of two contexts they had read or generated words. In Experiment 1, the contexts were two different rooms; in Experiment 2A, the contexts were two different computer screens; in Experiment 2B, the contexts were different perceptual characteristics of the to-be-remembered words. In all experiments, subjects were better at remembering the context of generated words than of read words.     

Complexity and coherency: integrating information in the brain

The brains of higher mammals are extraordinary integrative devices. Signals from large numbers of functionally specialized groups of neurons distributed over many brain regions are integrated to generate a coherent, multimodal scene. Signals from the environment are integrated with ongoing, patterned neural activity that provides them with a meaningful context. We review recent advances in neurophysiology and neuroimaging that are beginning to reveal the neural mechanisms of integration. In addition, we discuss concepts and measures derived from information theory that lend a theoretical basis to the notion of complexity as integration of information and suggest new experimental tests of these concepts.     

Pointing Unknowingly: Fantasy, Nonsense and 'Religious Understanding'

Lewis, Charles M. (ed.), Relativity and Religion
Tessin, Timothy and von der Ruhr, Mario (eds), Philosophy and the Grammar of Religious Belief     

Maltreated Children's Representations of Mother and an Additional Caregiver: A Longitudinal Study

ABSTRACT In the current longitudinal investigation, we explored the continuity of and changes in the mental representations of the mother and an additional caregiver among forty-five 9- to 11-year-old children who had been severely maltreated and subsequently placed in long-term residential care as well as the relationships between the content and structure of these representations and teacher's assessments of the child's externalizing and internalizing symptoms. At Time 1, a nonmaltreated comparison group was assessed concomitantly. Compared to nonmaltreated children, maltreated children scored higher for externalizing and internalizing symptoms, and their maternal representations were found to be significantly less benevolent and integrated and more punitive. In addition, among the maltreated children, the additional caregiver representations were found to be more benevolent and integrated, and less punitive, than the maternal representations. After 30 months, the maltreated children's levels of externalizing and internalizing symptoms diminished, their maternal representations become more benevolent and less punitive, and the additional caregiver representations became less benevolent. Moreover, the Benevolence of the additional caregiver representation was found to predict these children's changes in externalizing symptoms beyond the effects of their symptomatology and its associations with the Benevolence of these representations at Time 1.     

Psychological adaptation to ICDs and the influence of anxiety sensitivity

Forty-nine patients scheduled for implantable cardioverter defibrillator (ICD) implantation completed self-report psychological questionnaires prior to surgery and at 2, 4 and 6 months after surgery. The most common psychological problem identified was anxiety, with clinically significant cases based on the Depression Anxiety and Stress Scale (DASS) ranging between 26% and 34%. Clinically significant depression ranged between 8% and 20%. Anxiety sensitivity was associated with high levels of anxiety, depression and stress at baseline, but not at follow-up assessments. It is possible that within this population anxiety sensitivity is associated with distress during high-threat situations, but the relationship diminishes once the threat has passed. In addition, the reassurance provided by the ICD may reduce negative perceptions of symptoms, promoting psychological adaptation.