Human performance on visually presented Traveling Salesman problems

Little research has been carried out on human performance in optimization problems, such as the Traveling Salesman problem (TSP). Studies by Polivanova (1974, Voprosy Psikhologii, 4, 41–51) and by MacGregor and Ormerod (1996, Perception & Psychophysics, 58, 527–539) suggest that: (1) the complexity of solutions to visually presented TSPs depends on the number of points on the convex hull; and (2) the perception of optimal structure is an innate tendency of the visual system, not subject to individual differences. Results are reported from two experiments. In the first, measures of the total length and completion speed of pathways, and a measure of path uncertainty were compared with optimal solutions produced by an elastic net algorithm and by several heuristic methods. Performance was also compared under instructions to draw the shortest or the most attractive pathway. In the second, various measures of performance were compared with scores on Raven's advanced progressive matrices (APM). The number of points on the convex hull did not determine the relative optimality of solutions, although both this factor and the total number of points influenced solution speed and path uncertainty. Subjects' solutions showed appreciable individual differences, which had a strong correlation with APM scores. The relation between perceptual organization and the process of solving visually presented TSPs is briefly discussed, as is the potential of optimization for providing a conceptual framework for the study of intelligence. Received: 28 December 1998 / Accepted: 20 January 2000     

Distributing working memory resources during problem solving

This study examines how problem solvers distribute working memory demands over internal and external resources. Participants recorded notes while performing an arithmetic task. They recorded a majority of intermediate results and labeled many of those results (e.g., "C = 10"). When more effort was required to take notes, participants recorded fewer results. Participants with a consistent goal structure recorded fewer results and with practice labeled fewer recorded results than those with varied goal structures. When notes were displayed in a consistent spatial arrangement participants labeled fewer recorded results than when notes appeared in varied locations. These findings indicate that individuals use explicit and implicit strategies for indexing intermediate results. The data support the view that individuals flexibly distribute working memory over internal and external resources in response to situational cost-benefit considerations.     

A behavioral study of alpha-1b adrenergic receptor knockout mice: increased reaction to novelty and selectively reduced learning capacities

Knockout mice lacking the alpha-1b adrenergic receptor were tested in behavioral experiments. Reaction to novelty was first assessed in a simple test in which the time taken by the knockout mice and their littermate controls to enter a second compartment was compared. Then the mice were tested in an open field to which unknown objects were subsequently added. Special novelty was introduced by moving one of the familiar objects to another location in the open field. Spatial behavior and memory were further studied in a homing board test, and in the water maze. The alpha-1b knockout mice showed an enhanced reactivity to new situations. They were faster to enter the new environment, covered longer paths in the open field, and spent more time exploring the new objects. They reacted like controls to modification inducing spatial novelty. In the homing board test, both the knockout mice and the control mice seemed to use a combination of distant visual and proximal olfactory cues, showing place preference only if the two types of cues were redundant. In the water maze the alpha-1b knockout mice were unable to learn the task, which was confirmed in a probe trial without platform. They were perfectly able, however, to escape in a visible platform procedure. These results confirm previous findings showing that the noradrenergic pathway is important for the modulation of behaviors such as reaction to novelty and exploration, and suggest that this is mediated, at least partly, through the alpha-1b adrenergic receptors. The lack of alpha-1b adrenergic receptors in spatial orientation does not seem important in cue-rich tasks but may interfere with orientation in situations providing distant cues only.     

Functional recovery of skilled forelimb use in rats obliged to use the impaired limb after grafting of the frontal cortex lesion with homotopic fetal cortex

The long-term effect of transplanting embryonic frontal cortex into a unilateral frontal cortex lesion has been studied in adult rats. Before surgery, activity in an open field, muscular strength of both forelimbs, and performance in a paw-reaching-for-food task were scored in 26 rats. In 21 animals a unilateral cortex lesion was then made in the forelimb motor area of the hemisphere contralateral to the preferred paw in the paw-reaching-for-food task, while the other 5 animals were sham-operated. On retesting, the lesion animals changed the preferred paw. A solid homotopic transplant of embryonic tissue (embryonic day 17) was then placed in the lesion cavity in 11 of the lesion rats. Three months later neither lesion alone nor lesion plus transplantation affected open field behavior and muscular strength, but the lesion permanently affected performance in the paw-reaching-for-food task, as shown by a change of preferred paw and a functional deficit in the paw contralateral to the lesion. Transplantation ameliorated the deficits caused by the lesion, but this was only evident when animals were forced to reach with the paw contralateral to the lesion plus transplant. The behavioral results were independent of the size of the lesion and graft. Connections between graft and host tissue were studied by means of the fluorescent tracer 1,1'-dioctadecyl-3,3,3'3'-tetramethylindocarbocyanine perchlorate (DiI). A dense array of labeled fibers was found in the host cortex adjacent to the transplant. The results suggest that functional recovery depends on grafting but is only evident when the animal is obliged to use the affected limb.     

Test-retest reliability of the Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt in chronic schizophrenics

This study assesses the test-retest reliability of the revised Advanced Psychodiagnostic Interpretation (API) scoring system for the Bender Gestalt Test (BGT). The API system identifies 207 possible distortions in a BGT protocol. Test-retest reliability for 40 schizophrenic patients tested twice with a mean interval of 6.4 years (SD=3.8 years) was good, ranging from .71 to .80. Further reliability and validity studies are needed to further demonstrate the effectiveness of the system.     

The case for sensorimotor coding in working memory

The highly influential Baddeley and Hitch model of working memory (Baddeley & Hitch, 1974; see also Baddeley, 1986) posited analogical forms of representation that can be broadly characterized as sensorimotor, both for verbal and for visuospatial material. However, difficulties with the model of verbal working memory in particular have led investigators to develop alternative models that avoid appealing either to sensory coding or to motoric coding, or to both. This paper examines the evidence for sensorimotor coding in working memory, including evidence from neuropsychology and from sign language research, as well as from standard working memory paradigms, and concludes that only a sensorimotor model can accommodate the broad range of effects that characterize verbal working memory. In addition, several findings that have been considered to speak against sensorimotor involvement are reexamined and are argued to be in fact compatible with sensorimotor coding. These conclusions have broad implications, in that they support the emerging theoretical viewpoint of embodied cognition.     

Ethics and engineering courses at Delft University of Technology: Contents, educational setup and experiences

This article reports on the development and teaching of compulsory courses on ethics and engineering at Delft University of Technology (DUT). Attention is paid to the teaching goals, the educational setup and methods, the contents of the courses, involvement of staff from engineering schools, experiences to date, and challenges for the future. The choices made with respect to the development and teaching of the courses are placed within the European and Dutch context and are compared and contrasted with the American situation and experiences. Previous versions of this article were presented at the meeting of the SEFI Working Group on Engineering Ethics in Rzeszow, Poland, April 29–May 1, 1999 and at the SEFI Annual Conference in Zurich, Switzerland, September 1–3, 1999.     

Towards a research programme for ethics and technology

In this editorial contribution, two issues relevant to the question, what should be at the top of the research agenda for ethics and technology, are identified and discussed. Firstly: can, and do, engineers make a difference to the degree to which technology leads to morally desirable outcomes? What role does professional autonomy play here, and what are its limits? And secondly, what should be the scope of engineers' responsibility; that is to say, on which issues are they, as engineers, morally obliged to reflect? The research agendas proposed by the authors contributing to this special section, implicitly, give different answers to these questions. We suggest that an explicit discussion of these issues would greatly help in constructing a common research agenda.     

The professional approach to engineering ethics: five research questions

This paper argues that research for engineering ethics should routinely involve philosophers, social scientists, and engineers, and should focus for now on certain basic questions such as: Who is an engineer? What is engineering? What do engineers do? How do they make decisions? And how much control do they actually have over what they do?