ndividual creativity is standardly treated as an ‘internalist’ process occurring solely in the head. An alternative, more interactionist view is presented here, where working with objects, media and other external things is seen as a fundamental component of creative thought. The value of chance interaction and chance cueing — practices widely used in the creative arts — is explored briefly in an account of the creative method of choreographer Wayne McGregor and then more narrowly in an experimental study that compared performance on a Scrabble-like word discovery problem. Subjects were presented with seven letters and given two minutes to call out three-to-seven-letter English words. There were three conditions: The tiles were fixed in place, subjects were free to move the tiles manually or the tiles could be randomly shuffled. Results showed that random shuffling was best, with manual movement second. Three reasons are provided: Shuffling is faster and cheaper than mentally thinking of candidates; randomizing strings covers the search space better than a deterministic method based on past successes; and randomizing is equivalent to adding diversity to a team, which is known empirically to lead to more creative solutions.

Why do people create extra representations to help them make sense of situations, diagrams, illustrations, instructions and problems? The obvious explanation—external representations save internal memory and computation—is only part of the story. I discuss seven ways external representations enhance cognitive power: they change the cost structure of the inferential landscape; they provide a structure that can serve as a shareable object of thought; they create persistent referents; they facilitate re-representation; they are often a more natural representation of structure than mental representations; they facilitate the computation of more explicit encoding of information; they enable the construction of arbitrarily complex structure; and they lower the cost of controlling thought—they help coordinate thought. Jointly, these functions allow people to think more powerfully with external representations than without. They allow us to think the previously unthinkable.

Réflexions sur la surcharge cognitive. Cet article aborde le problème de la saturation cognitive tel que les individus le vivent au quotidien sur leur lieu de travail. Il examine d'abord une série d'hypothèses sur les causes de ce phénomène : trop d'information en "push" et en "pull", le multi-tâche et les interruptions, un environnement de travail mal conçu. En passant, il pose une série de questions : la mesure de la qualité de l'information, la forme de sa fonction d'utilité, la pertinence de différentes stratégies de gestion des flux. Ensuite, il cherche à bâtir un cadre d'analyse pour améliorer la conception des environnements de travail. Il enrichit la formalisation de Simon et Newell sur l'espace de la tâche, en montrant que les stratégies cognitives du sujet peuvent l'amener à des détours qui, sans être des tâches proprement dites, sont des reformulations du problème qui facilitent sa résolution. Cette avancée permet de poser plus clairement la question de la charge cognitive et des coûts cognitifs qui découlent de l'environnement. L'article distingue notamment la charge de calcul, la mémoire, la concentration, le stress. Il montre sur quelques exemples simples comment un réaménagement de l'environnement peut abaisser la structure de coûts pour l'opérateur, et lui procurer une aide dans son travail cognitif .

This essay has three parts. In Part 1, I review six biases that frame the way architects and human–computer interaction (HCI) practitioners think about their design problems. These arise from differences between working on procedurally complex tasks in peripersonal space like writing or sketching and being immersed in larger physical spaces where we dwell and engage in body-sized activity like sitting, chatting, and moving about. In Part 2, I explore three types of interface: classical HCI, network interfaces such as context-aware systems, and socio-ecological interfaces. An interface for an architect is a niche that includes the very people who interact with it. In HCI, people are still distinct from the interface. Because of this difference, architectural conceptions may be a fertile playground for HCI. The same holds for interactivity. In Part 3, I discuss why interactivity in HCI is symmetric and transitive. Only in ecological and social interaction is it also reflexive. In ecological interfaces, people co-create bubbles of joint awareness where they share highly situated values, experience, and knowledge.