Contemporaneous Statistics for Estimation in Stochastic Actor-Oriented Co-evolution Models

Psychometrika - Stochastic actor-oriented models (SAOMs) can be used to analyse dynamic network data, collected by observing a network and a behaviour in a panel design. The parameters of SAOMs are...     

The psychometric function: II. Bootstrap-based confidence intervals and sampling

The psychometric function relates an observer’s performance to an independent variable, usually a physical quantity of an experimental stimulus. Even if a model is successfully fit to the data and its goodness of fit is acceptable, experimenters require an estimate of the variability of the parameters to assess whether differences across conditions are significant. Accurate estimates of variability are difficult to obtain, however, given the typically small size of psychophysical data sets: Traditional statistical techniques are only asymptotically correct and can be shown to be unreliable in some common situations. Here and in our companion paper (Wichmann & Hill, 2001), we suggest alternative statistical techniques based on Monte Carlo resampling methods. The present paper’s principal topic is the estimation of the variability of fitted parameters and derived quantities, such as thresholds and slopes. First, we outline the basic bootstrap procedure and argue in favor of the parametric, as opposed to the nonparametric, bootstrap. Second, we describe how the bootstrap bridging assumption, on which the validity of the procedure depends, can be tested. Third, we show how one’s choice of sampling scheme (the placement of sample points on the stimulus axis) strongly affects the reliability of bootstrap confidence intervals, and we make recommendations on how to sample the psychometric function efficiently. Fourth, we show that, under certain circumstances, the (arbitrary) choice of the distribution function can exert an unwanted influence on the size of the bootstrap confidence intervals obtained, and we make recommendations on how to avoid this influence. Finally, we introduce improved confidence intervals (bias corrected and accelerated) that improve on the parametric and percentile-based bootstrap confidence intervals previously used. Software implementing our methods is available.     

Beyond Single-Mindedness: A Figure-Ground Reversal for the Cognitive Sciences

A fundamental fact about human minds is that they are never truly alone: all minds are steeped in situated interaction. That social interaction matters is recognized by any experimentalist who seeks to exclude its influence by studying individuals in isolation. On this view, interaction complicates cognition. Here, we explore the more radical stance that interaction co-constitutes cognition: that we benefit from looking beyond single minds toward cognition as a process involving interacting minds. All around the cognitive sciences, there are approaches that put interaction center stage. Their diverse and pluralistic origins may obscure the fact that collectively, they harbor insights and methods that can respecify foundational assumptions and fuel novel interdisciplinary work. What might the cognitive sciences gain from stronger interactional foundations? This represents, we believe, one of the key questions for the future. Writing as a transdisciplinary collective assembled from across the classic cognitive science hexagon and beyond, we highlight the opportunity for a figure-ground reversal that puts interaction at the heart of cognition. The interactive stance is a way of seeing that deserves to be a key part of the conceptual toolkit of cognitive scientists.     

Interaction between preference and instructions for a focus of attention in billiards

The present study evaluated the interaction between preference for a focus of attention and instructions for focusing attention. 4 experienced billiard players had to shoot a billiard ball into a target area and received a focus instruction either corresponding or opposite to their preferred focus of attention. Two-dimensional error scores of accuracy and consistency were obtained. Accuracy of performance increased between Phase 1 without instructions and Phase 2 with focus instructions, independent of preference or instruction. However, participants with a preference for an external focus receiving an internal focus instruction showed less consistent performance.     

Group decision making in hidden profile situations: dissent as a facilitator for decision quality

The effect of diversity in individual prediscussion preferences on group decision quality was examined in an experiment in which 135 three-person groups worked on a personnel selection case with 4 alternatives. The information distribution among group members constituted a hidden profile (i.e., the correct solution was not identifiable on the basis of the members' individual information and could be detected only by pooling and integrating the members' unique information). Whereas groups with homogeneous suboptimal prediscussion preferences (no dissent) hardly ever solved the hidden profile, solution rates were significantly higher in groups with prediscussion dissent, even if none of these individual prediscussion preferences were correct. If dissent came from a proponent of the correct solution, solution rates were even higher than in dissent groups without such a proponent. The magnitude of dissent (i.e., minority dissent or full diversity of individual preferences) did not affect decision quality. The beneficial effect of dissent on group decision quality was mediated primarily by greater discussion intensity and to some extent also by less discussion bias in dissent groups.     

Enhancing picture naming with transcranial magnetic stimulation

The enhancement of cognitive function in healthy subjects by medication, training or intervention yields increasing political, social and ethical attention. In this paper facilitatory effects of single-pulse TMS and repetitive TMS on a simple picture naming task are presented. A significant shortening of picture naming latencies was observed after single-pulse TMS over Wernicke's area. The accuracy of the response was not affected by this speed effect. After TMS over the dominant motor cortex or over the non-dominant temporal lobe, however, no facilitation of picture naming was observed. In the rTMS experiments only rTMS of Wernicke's area had an impact on picture naming latencies resulting in a shortening of naming latencies without affecting the accuracy of the response. rTMS over the visual cortex, Broca's area or over the corresponding sites in the non-dominant hemisphere had no effect. Single-pulse TMS is able to facilitate lexical processes due to a general preactivation of language-related neuronal networks when delivered over Wernicke's area. Repetitive transcranial magnetic stimulation over Wernicke's area also leads to a brief facilitation of picture naming possibly by shortening linguistic processing time. Whether TMS or rTMS can be used to aid linguistic therapy in the rehabilitation phase of aphasic patients should be subject of further investigations.     

Information sampling and group decision making: the effects of an advocacy decision procedure and task experience

Group discussions tend to focus on information that was previously known by all members (shared information) rather than information known by only 1 member (unshared information). If the shared information implies a suboptimal alternative, this sampling bias is associated with inaccurate group decisions. The present study examines the impact of 2 factors on information exchange and decision quality: (a) an advocacy group decision procedure versus unstructured discussion and (b) task experience. Results show that advocacy groups discussed both more shared and unshared information than free-discussion groups. Further, with increasing experience, more unshared information was mentioned in advocacy groups. In contrast, there was no such increase in unstructured discussions. Yet advocacy groups did not significantly improve their decision quality with experience.     

The contributions of color to recognition memory for natural scenes

The authors used a recognition memory paradigm to assess the influence of color information on visual memory for images of natural scenes. Subjects performed 5%-10% better for colored than for black-and-white images independent of exposure duration. Experiment 2 indicated little influence of contrast once the images were suprathreshold, and Experiment 3 revealed that performance worsened when images were presented in color and tested in black and white, or vice versa, leading to the conclusion that the surface property color is part of the memory representation. Experiments 4 and 5 exclude the possibility that the superior recognition memory for colored images results solely from attentional factors or saliency. Finally, the recognition memory advantage disappears for falsely colored images of natural scenes: The improvement in recognition memory depends on the color congruence of presented images with learned knowledge about the color gamut found within natural scenes. The results can be accounted for within a multiple memory systems framework.     

Literatur in Examensarbeiten

After the Second World War up to the 1980s Harald Schultz-Hencke’s so-called German neopsychoanalysis was an important theoretical reference for psychoanalysts in the German Psychoanalytical Society (DPG). Simultaneously, however, references were increasingly being made to quintessential psychoanalytical sources which of course had an impact on the psychoanalytical training. The references in final papers of a DPG psychoanalytical institute from 1971–2008 were compared to the references in clinical papers of the International Journal of Psychoanalysis. It can be shown that the influence of German neopsychoanalysis in the final theses of the psychoanalytical institute in question has diminished since the 1990s and has become irrelevant in the twenty-first century.     

Book reviews

Islam and Politics in Central Asia by M. Haghayeghi. London: Macmillan, 1995, 264 pp.

Empire's Edge: Travels in South‐Eastern Europe, Turkey and Central Asia by Scott Malcomson. Boston USA and London: Faber and Faber, 1994, 256 pp. Paperback, £8.99.

The Resurgence of Central Asia: Islam or Nationalism by Ahmed Rashid. London and New Jersey: Zed Books, 1994, x+278 pp. Hardback, £36.95, $59.95; Paperback, £14.95, $25.00.

Pride of Small Nations: The Caucasus and Post‐Soviet Disorder by Suzanne Golden‐berg. London and New Jersey: Zed Books, 1994. xvi+233 pp. Hardback, £36.95, $55.00; Paperback, £14.95, $22.50.

The North Caucasus Barrier: the Russian Advance towards the Muslim World edited by M. Bennigsen Broxup. London: Hurst, 1992, xvii+252 pp. Hardback. Paperback, 1996, £14.95.