Dodge-ing the issue: Dodge,Javal, Hering,and the measurement of saccades in eye-movement research

Dodge, in 1916, suggested that the French term 'saccade' should be used for describing the rapid movements of the eyes that occur while reading. Previously he had referred to these as type I movements. Javal had used the term 'saccade' in 1879, when describing experiments conducted in his laboratory by Lamare. Accordingly, Javal has been rightly credited with assigning the term to rapid eye movements. In English these rapid rotations had been called jerks, and they had been observed and measured before Lamare's studies of reading. Rapid sweeps of the eyes occur as one phase of nystagmus; they were observed by Wells in 1792 who used an afterimage technique, and they were illustrated by Crum Brown in 1878. Afterimages were used in nineteenth-century research on eye movements and eye position; they were also employed by Hering in 1879, to ascertain how the eyes moved during reading. In the previous year, Javal had employed afterimages in his investigations of reading, but this was to demonstrate that the eyes moved horizontally rather than vertically. Hering's and Lamare's auditory method established the discontinuous nature of eye movements during reading, and the photographic methods introduced by Dodge and others in the early twentieth century enabled their characteristics to be determined with greater accuracy.     

Visual perspective taking for avatars in a Simon task

In modern digital applications, users often interact with virtual representations of themselves or others, called avatars. We examined how these avatars and their perspectives influence stimulus–response compatibility in a Simon task. Participants responded to light/dark blue stimuli with left/right key presses in the presence of a task-irrelevant avatar. Changes in stimulus–response compatibility were used to quantify changes in the mental representation of the task and perspective taking toward this avatar. Experiments 1 and 2 showed that perspective taking for an avatar occurred in orthogonal stimulus–response mappings, causing a compatibility effect from the avatar’s point of view. In the following two experiments we introduced a larger variety of angular disparities between the participant and avatar. In Experiment 3, the Simon effect with lateralized stimulus positions remained largely unaffected by the avatar, pointing toward an absence of perspective taking. In Experiment 4, after avatar hand movements were added in order to strengthen the participants’ sense of agency over the avatar, a spatial compatibility effect from the avatar’s perspective was observed again, and hints of the selective use of perspective taking on a trial-by-trial basis were found. Overall, the results indicate that users can incorporate the perspective of an avatar into their mental representation of a situation, even when this perspective is unnecessary to complete a task, but that certain contextual requirements have to be met.     

Knowledge level learning and the power law: A soar model of skill acquisition in scheduling

Zusammenfassung. Das hier vorgestellte Modell lernt graduell, Planungsaufgaben aus der Klasse der Maschinenbelegungsprobleme (job-shop-scheduling problems) zu lösen. Mit Hilfe des Chunking-Mechanismus von Soar wird episodisches Wissen über die Belegungsreihenfolge von Aufträgen auf Maschinen memoriert. Bei der Entwicklung des Modells wurden zahlreiche qualitative (z. B. Transfereffekte) und quantitative Befunde (z. B. Bearbeitungszeiten) aus einer früheren empirischen Untersuchung berücksichtigt. In einer Validierungsstudie wurden dieselben Aufgaben von 14 Probanden und dem Modell bearbeitet. Die Passung von Simulationsdaten und empirischen Ergebnissen fiel insgesamt gut aus. Allerdings löst das Modell die Aufgaben schneller und zeigt auch einen etwas besseren Lernverlauf als die Probanden. Das Modell liefert eine Erklärung für das Rauschen, das typischerweise bei Bearbeitungszeiten zu beobachten ist: es handelt sich um erworbenes Wissen, das mehr oder weniger gut und auch unterschiedlich häufig auf neue Situationen übertragen wird. Der Lernverlauf der Probanden entspricht nur für aggregierte Daten einer Potenzfunktion (power law). Der vorgestellte Mechanismus zeigt, wie ein symbolisches Modell der Informationsverarbeitung graduelle Verhaltensänderungen generiert und wie der offensichtliche Erwerb allgemeiner Prozeduren ohne explizites Lernen von deklarativen Regeln erfolgen kann. Es wird nahegelegt, daß es sich hier um die Modellierung einer Form impliziten Lernens handelt. Summary. The model presented here gradually learns how to perform a job-shop scheduling task. It uses Soar's chunking mechanism to acquire episodic memories about the order to schedule jobs. The model was based on many qualitative (e.g., transfer effects) and quantitative (e.g., solution time) regularities found in previously collected data. The model was tested with new data where scheduling tasks were given to the model and to 14 subjects. The model generally fit these data with the restrictions that the model performs the task (in simulated time) faster than the subjects, and its performance improves somewhat more quickly than the subjects' performance. The model provides an explanation of the noise typically found in problem solving times - it is the result of learning actual pieces of knowledge that transfer more or less to new situations but rarely by an average amount. Only when the data are averaged (i.e., over subjects) does the smooth power law appear. This mechanism demonstrates how symbolic models can exhibit a gradual change in behavior and how the apparent acquisition of general procedures can be performed without resorting to explicit declarative rule generation. We suggest that this may represent a type of implicit learning.     

The puzzle of language evolution

Linguistics must again concentrate on the evolutionary nature of language, so that language models are more realistic with respect to human natural languages and have a greater explanatory force. Multi-agent systems are proposed as a possible route to develop such evolutionary models and an example is given of a concrete experiment in the origins and evolution of word-meaning based on a multi-agent approach.     

Molecular geneticists and moral responsibility: “maybe if we were working on the atom bomb I would have a different argument”

Senior molecular geneticists were interviewed about their perceptions of the ethical and social implications of genetic knowledge. Inductive analysis of these interviews identified a number of strategies through which the scientists negotiated their moral responsibilities as they participated in generating knowledge that presents difficult ethical questions. These strategies included: further analysis and application of scientific method; clarification of multiple roles; negotiation with the public through public debate, institutional processes of funding, ethics committees and legislation; and personal responsibility.     

What is bioethics without Christianity?

The author uses the essays in this issue as a springboard for making three points. First, he argues that most, if not all, current institutional versions of Christianity have failed to provide a meaningful framework for the spiritual life. Second, he argues that there is no ethics other than Judeo-Christian ethics and that there can be no bioethics other than Judeo-Christian bioethics. Finally, he argues that the overriding issue we face is not whether to address bioethical issues from a Christian perspective or from a non-Christian perspective, but rather whether we shall address biological and medical issues from an ethical or a scientific-technological perspective.     

One extreme or the other or perhaps the golden mean? Issues of spatial resolution in face processing

The findings of some of the key studies that have examined the contribution of different bands of spatial information, specified in terms of cycles per face, to face recognition, and identification are reviewed. Based on findings from studies of low-, high-, and band-pass filtering, it is concluded that neither low facial scales nor high facial scales are optimal. Instead, a center range of facial scales, approximately 8-16 cycles per face, appears to make the greatest contribution to the recognition process. A study of identification of band-pass filtered faces is reported that reinforces the view derived from the literature. This indicated that a band with a harmonic mean of 11.1 cycles per face provided the most efficient recognition, with speed and accuracy declining at lower and higher bands.     

Quasi-Realism, Negation and the Frege-Geach Problem

Every expressivist theory of moral language requires a solution to the Frege-Geach problem, i.e., the problem of explaining how moral sentences retain their meaning in unasserted (e.g., conditional and disjunctive) contexts. An essential part of Blackburn's ' quasi -realist project', i.e., the project of showing how we can earn the right to treat moral sentences as if they have ordinary truth-conditions, is to provide a sophisticated solution. I show, however, that simple negated contexts provide a fundamental difficulty, since accepting the negation of a sentence is easily confused with merely refusing to accept that sentence. I argue that Blackburn's model-set semantics for his 'Hooray!' and 'Boo!' operators requires logical apparatus to which he is not entitled. I consider various modifications, but show that they do not succeed.
email : n.unwin@bolton.ac.uk