Expertise and skill in minimally invasive surgery.

New attitudes to medical ethics and demands for efficiency have brought increased attention to surgical skills and training. It is important to characterize the expertise and skill involved in the multidimensional surgical profession. At a time of change, there is a need to discuss the nature of surgical expertise, and also the prospects for resident training, with special reference to new minimally invasive techniques (MIS). In this paper, we selectively review knowledge on surgical expertise and the specific demands placed on a skilled MIS surgeon. In addition, the review contains a selection of studies from those areas that have been seen as important for the future of training in surgery.

Taxi drivers' exceptional memory of street names.

In this paper, we explore the nature of taxi drivers' serial recall of street names. The main question is whether the memory of verbal material benefits from the possibility of using visuospatial associations and knowledge concerning large-scale environment. In two experiments, expert taxi drivers' recall of street names was superior to that of control groups. In Experiment 1, experts' superiority of memory was greater when the street names reflected a visuospatially continuous route than when the street names were located along a straight line across the map without spatial continuity or were presented in random order. In Experiment 2, the expert taxi drivers recalled spatially continuously organized lists much better than they recalled lists of street names belonging to the same semantic category or lists presented in alphabetical order. This result also suggests that interitem associations, which are based on spatial co-occurrence, are efficient in comparison with other mnemonics.

Novice construction of chess memory.

Novice acquisition of skilled recall of chess positions was studied in an experiment in which two novices studied a series of five hundred chess positions during a period of several months. They spent fifteen minutes to half an hour a day teaching themselves these positions. As a result their skill in recalling chess positions rose from sixteen percent to somewhere between forty to fifty percent. The learning curve proved to have a shape which indicates that in the beginning learning is very fast but after some 100-150 studied positions the speed of learning decreases substantially. A computer simulation was used to model the results and analyse alternative explanations. Two alternative ways of thinking were tested. In the first, chunk construction was assumed to be based on the neighbourhood of associated pieces. The second model assumed a frequency-based correlative association process. Although the learning curves of the two models are very similar in shape to those of the subjects, the frequency-based associative model gave a better explanation for the data. This is why it is natural to suggest that common co-occurrence in addition to easily recognizable chess-specific characteristics, like colour and type of pieces, guide associative processes during chess players' learning of chess-specific chunks.

What do computer models of cognition explain: a reply to Gobet.

The differences between Gobet's views and ours call attention to some points concerning the argumentative status of computational models. If we have two fundamentally different models which reasonably accurately simulate a phenomenon, we must ask, what is the argumentative status of the models in psychological terms. Moreover, if it is possible to present different models of same phenomena, what is the general argumentative power of models in psychology? As the kind of differences between our views and the ones of Gobet's are common in modelling, we briefly call attention to these foundational issues in our paper.

Apperception and imagery in blindfold chess.

Apperception constructs functional and "meaningful" mental representations. These representations are often built on mental images. Hence it is rational to assume that the contents of some parts of images may be functionally more important than others. This means that the cognitive processing of some parts of the image is more effective than for others. To extract this preferential structure, which we call the functional figure in mental images, five experiments were conducted on blindfold chess imagery. We showed that blindfold chess players have much better recall of functionally significant than of functionally insignificant areas of chess positions. Thus, of the various mental representations of chess board areas, the functionally more significant areas are better represented than others.

Semantic distance and single cue use in category search.

Perceptual classification may be based either on the physical features of target and background items or on the semantic attributes of the presented items. In this paper we used enumeration tasks to study the role of semantic features in a categorial classification task. This means that subjects were asked to count the number of target words in a display belonging to one semantic category among a number of background items of other categories. Our goal was to study the decision logic in category search by manipulating target background conditions and the semantic distance between target and background classes. In the first experiment we found that the larger the semantic distance between targets and background words, the easier it was to find the targets. In the second experiment we found a "pop-out" effect, in which subjects could use and benefit from a single distinctive semantic feature, "part-likeness", in categorial classification. The results of the two experiments imply that the categorization decision logic is basically the same in physical and semantic perceptual classification.

Do visual images have Gestalt properties?

Recent research has demonstrated that percepts and images share processing resources. A natural consequence of this evidence is to ask what kind of properties are shared by the two representational systems, i.e. images and percepts. To what degree, for example, do images share the complex organization of visual percepts? This paper investigates whether percepts and images share Gestalt properties. Four experiments were conducted to study this hypothesis. In all experiments subjects were presented with an auditory message in which approximately 15 locations in a matrix were defined by giving the co-ordinates of the cells. Half of the stimuli presented some "good" form, whereas in the other half the locations of the pieces were scattered. Subjects were systematically less able to recall the locations of the random forms. Therefore, it could be argued that the "good" forms help in image construction, even though the elements were auditorily presented. Effects of varying presentation speed, order, and of requiring a mental rotation before recall support this conclusion.

Error in chess: the apperception-restructuring view.

Five protocol-analysis experiments with tactical, endgame, and strategic positions were conducted to study cognitive errors in chess players' thinking. It will be argued that chess players' errors can be only partially explained in terms of unspecified working-memory overload, because the working-memory loads caused by the solution paths are usually small. It is therefore necessary to consider apperceptive mechanisms also, as these control information intake. Subjects fail either because they are not able to see the right prototypical problem space at all, or because they fail to close them as a result of missing some crucial task-relevant cue. This makes chess players lose their "belief in the idea" and restructure, after which the apperceptive information-selection mechanisms make the finding of the solution still more unlikely.

Aspects of skilled imagery in blindfold chess.

Blindfold chess is a very good task environment to study skill-based mental images or skilled imagery. Seven experiments providing information on different aspects of skilled imagery in blindfold chess were made. In all experiments very clear skill-related differences in the operation of chess-specific materials could be found. It will also be argued that chess-specific patterns or chunks are important in skilled subjects' construction of images and the operation of these images relies on the cooperation of visual working memory and long-term memory.