The architecture of complexity: A new blueprint

The logic of scientific discovery is now a concern of computer scientists, as well as philosophers. In the computational approach to inductive inference, theories are treated as algorithms (computer programs), and the goal is to find the simplest algorithm that can generate the given data. Both computer scientists and philosophers want a measure of simplicity, such that simple theories are more likely to be true than complex theories. I attempt to provide such a measure here. I define a measure of simplicity for directed graphs, inspired by Herbert Simon's work. Many structures, including algorithms, can be naturally modelled by directed graphs. Furthermore, I adapt an argument of Simon's to show that simple directed graphs are more stable and more resistant to damage than complex directed graphs. Thus we have a reason for pursuing simplicity, other than purely economical reasons.This paper is based on part of my doctoral dissertation. Thanks to my thesis supervisor Professor Alasdair Urquhart for his encouragement, constructive criticism, and for directing me to several relevant articles; to my advisor, Professor Ian Hacking, for reminding me to concentrate on results that might have some application in the real world; to Professor Eric Mendelsohn for checking my use of graph theory; and to my friend Wendy Brandts for sharing her ideas on a closely related problem.Thanks to my friends and family (the latter being a (proper) subset of the former, and both including Dr. Louise Linney, of course) for ongoing support in my scholastic endeavors.Thanks to the Social Sciences and Humanities Research Council for financial assistance. (Awards 452-86-5885 and 453-87-0513.) Thanks to the University of Toronto for financial assistance.     

Embeddability,syntax, and semantics in accounts of scientific theories

Recently several philosophers of science have proposed what has come to be known as the semantic account of scientific theories. It is presented as an improvement on the positivist account, which is now called the syntactic account of scientific theories. Bas van Fraassen claims that the syntactic account does not give a satisfactory definition of empirical adequacy and empirical equivalence. He contends that his own semantic account does define these notations acceptably, through the concept of embeddability, a concept which he claims cannot be defined syntactically. Here, I define a syntactic relation which corresponds to the semantic relation of embeddability. I suggest that the critical differences between the positivist account and van Fraassen's account have nothing to do with the distinction between semantics and syntax.     

The rhinal cortex: 'gatekeeper' of the declarative memory system

Almost all studies probing neural activity underlying the declarative memory system in humans have investigated either memory encoding or retrieval. Here, however, we suggest integrating encoding and retrieval operations into a single operation executed by the rhinal cortex. The more familiar an item is, the less rhinal processing it requires and the less vigorously it is encoded into memory. Given the anatomical position and the functional properties of the rhinal cortex, this operation fulfills an essential task: it optimally allocates limited encoding resources away from familiar information and towards novel information. We propose a rhinal processing stage that optimizes the declarative memory system by fully integrating encoding and retrieval operations into a single 'gatekeeper' operation.     

Reading rates of stutterers and nonstutterers during silent and oral reading

The purpose of this study was to investigate the differences between the reading rates of stutterers and nonstutterers during both silent and oral reading of fluently spoken words. Ten adult stutterers and 14 nonstutterers were instructed to read two lists of words over four trials each. The first trial of either the first or the second list was a silent reading trial. All the other trials were oral reading trials. The word lists consisted of nouns with word lengths from two to five syllables. The dependent variables were the silent and oral reading times per word and per syllable. The major findings were that stutterers, as compared to nonstutterers, required longer reading times per word and per syllable during both silent and oral reading. These results indicate that stutterers differ from nonstutterers in the basic processing time for verbal material.     

How Language Enables Abstraction: A Study in Computational Cultural Psychology

The idea that language mediates our thoughts and enables abstract cognition has been a key idea in socio-cultural psychology. However, it is not clear what mechanisms support this process of abstraction. Peirce argued that one mechanism by which language enables abstract thought is hypostatic abstraction, the process through which a predicate (e.g., dark) turns into an object (e.g., darkness). By using novel computational tools we tested Peirce’s idea. Analysis of the data provides empirical support for Peirce’s mechanism and evidence of the way the use of signs enables abstraction. These conclusions are supported by the in-depth analysis of two case studies concerning the abstraction of sweet and dark. The paper concludes by discussing the findings from a broad and integrative theoretical perspective and by pointing to computational cultural psychology as a promising perspective for addressing long-lasting questions of the field.     

THE ABSTRACT SUBLIME: Life as information waiting to be rewritten

We report here on a series of interaction-intensive, interdisciplinary workshops to foster collaboration among those who teach, study, and engage with the public about scientific developments and social change—the New England Workshop on Science and Social Change. We include one line of thinking that fed into the workshops and present an analysis of how they contribute to participants developing their interest and skills in collaboration. Workshop evaluations suggest that people are moved to develop themselves as collaborators when they view an experience or training as transformative. Four R's—respect, risk, revelation, and re-engagement—point to the important conditions for interactions among researchers to be experienced as transformative. Three considerations lie behind the focus on the process side of the workshops, not the specific workshop topics: (1) how best to fill in for readers what they missed out on by not being there; (2) workshops and meetings are a ubiquitous part of the culture of science and technology studies (STS) so it is valuable to examine this aspect of our own culture with a view to promoting positive changes; and (3) in some scientific fields organized multi-person collaborative processes form a highly valorized aspect of the culture of science, so reflection on experiences of participation and collaboration in STS might inform our analyses of fields that emphasize collaboration and group processes. Indeed, the authors' own involvement in the workshops extends our own STS work on actor networks and ‘heterogeneous engineering’, that is, the mobilization of a variety of resources by diverse agents spanning different realms of social action.     

Psychologists' attitudes toward aids

Abstract

Practicing psychologists in all areas of the country will see an increasing number of persons at risk for AIDS, or with AIDS-related illnesses. Previous research has shown that AIDS elicits negative reactions from the general public and from certain health care professionals. In the current study, a national sample of randomly selected practicing psychologists completed attitude measures after reading vignettes that described a male patient with either AIDS or leukemia who was either homosexual or heterosexual. Respondents evaluated the AIDS patient more negatively and reported less willingness to interact with him in a professional role or in casual social situations. It is important to develop training and continuing education programs to prepare psychologists to deal with persons affected by AIDS.     

Exploring the influence of encoding format on subsequent memory

Distinctive encoding is greatly influenced by gist-based processes and has been shown to suffer when highly similar items are presented in close succession. Thus, elucidating the mechanisms underlying how presentation format affects gist processing is essential in determining the factors that influence these encoding processes. The current study utilised multivariate partial least squares (PLS) analysis to identify encoding networks directly associated with retrieval performance in a blocked and intermixed presentation condition. Subsequent memory analysis for successfully encoded items indicated no significant differences between reaction time and retrieval performance and presentation format. Despite no significant behavioural differences, behaviour PLS revealed differences in brain–behaviour correlations and mean condition activity in brain regions associated with gist-based vs. distinctive encoding. Specifically, the intermixed format encouraged more distinctive encoding, showing increased activation of regions associated with strategy use and visual processing (e.g., frontal and visual cortices, respectively). Alternatively, the blocked format exhibited increased gist-based processes, accompanied by increased activity in the right inferior frontal gyrus. Together, results suggest that the sequence that information is presented during encoding affects the degree to which distinctive encoding is engaged. These findings extend our understanding of the Fuzzy Trace Theory and the role of presentation format on encoding processes.     

Contributions of the medial temporal lobe to declarative memory retrieval: manipulating the amount of contextual retrieval

We investigated how the hippocampus and its adjacent mediotemporal structures contribute to contextual and noncontextual declarative memory retrieval by manipulating the amount of contextual information across two levels of the same contextual dimension in a source memory task. A first analysis identified medial temporal lobe (MTL) substructures mediating either contextual or noncontextual retrieval. A linearly weighted analysis elucidated which MTL substructures show a gradually increasing neural activity, depending on the amount of contextual information retrieved. A hippocampal engagement was found during both levels of source memory but not during item memory retrieval. The anterior MTL including the perirhinal cortex was only engaged during item memory retrieval by an activity decrease. Only the posterior parahippocampal cortex showed an activation increasing with the amount of contextual information retrieved. If one assumes a roughly linear relationship between the blood-oxygenation level-dependent (BOLD) signal and the associated cognitive process, our results suggest that the posterior parahippocampal cortex is involved in contextual retrieval on the basis of memory strength while the hippocampus processes representations of item-context binding. The anterior MTL including perirhinal cortex seems to be particularly engaged in familiarity-based item recognition. If one assumes departure from linearity, however, our results can also be explained by one-dimensional modulation of memory strength.