Sexing day-old chicks: A case study and expert systems analysis of a difficult perceptual-learning task.

Abstract

The sexing of day-old chicks has been regarded as an extraordinarily difficult perceptual task requiring years of extensive practice for its mastery. Experts can sex chicks at over 98% accuracy at a rate of 1,000 chicks per hour spending less than a half second viewing the cloacal region. Naive subjects were shown 18 pictures of cloacal regions of male and female chicks (in random appearing arrangement) and asked to judge the sex of each chick. The pictures included a number of rare and difficult configurations. The subjects were then instructed as to the location of a critical cloacal structure for which a simple contrast in shape (convex vs. concave or flat) could serve as an indicant of sex. When the subjects judged the pictures again (in a different order), accuracy increased from slightly above chance to a level comparable to that achieved by a sample of experts. The correlation (over items) between the naive subjects and the experts before instruction was .21; after instruction, .82. The instructions were based on an interview and observation of an expert who had spent 50 years sexing 55 million chicks. Much of the reported difficulty in developing perceptual expertise in this task may stem from the need to classify extremely rare configurations in which the convexity of the structure is not apparent. The rate of learning of these instances could be greatly increased through the use of simple instructions that specified the location of diagnostic contour contrasts. A parallel is drawn between learning to sex chicks and learning to classify tanks as friend or foe.

Competing strategies in categorization: Expediency and resistance to knowledge restructuring.

“…For example, Mayer and Gallini (1990) showed that problem solving involving mechanical devices (e.g., car brakes) was facilitated when a previously shown explanation of those devices was accompanied by a diagram of the component parts and their functions. Likewise, Biederman and Shiffrar (1987) showed that novices, after minimal instruction with a few simple diagrams, could match the performance of highly skilled experts on a perceptual learning task. The task involved the sexing of day-old chicks, a commercially relevant skill that had previously defied pictorial representation or training and that previously could only be learned through extensive practice (up to 1,000,000 trials).…”

An ecological approach to cognitive (im)penetrability

“…In that case the expert can direct focal attention to the critical locations, allowing the independent visual process to do the rest. The most remarkable case of such expertise was investigated by Biederman and Shiffrar (1987) and involves expert "chicken sexers." Determining the sex of day-old chicks is both economically important and also apparently very difficult.…”

“…However, we would like to finish on another point related to the performance of expert perceivers. Pylyshyn considers the case of chick sexing (Biederman & Shiffrar 1987) and argues that instruction teaches the sexer how "to bring the independent visual system to bear at the right spatial location" (sect. 6.2, para.…”

“…Although model-based systems may not use general knowledge and draw inferences, they fall into the knowledge-based category because they quite explicitly use knowledge about particular objects in deciding whether a scene contains instances of these objects. Even though in some cases they may use some form of "general purpose" model of objects (Lowe 1987;Zucker et al 1975) -or even of parts of such objects (Biederman 1987) -the operation of the systems depends on prior knowledge of particulars. In addition, it is widely held that the larger the domain over which the vision system must operate, the less likely it is that a single type of stored information will allow reliable recognition.…”

“…Identification is typically modeled with long term shape memory incorporated into the shape description process (e.g., Biederman 1987;Edelman 1998;McClelland & Rumelhart 1981;Ullman 1989). This is done because of ubiquitous familiarity effects -advantages in perceptibility for more familiar words, facial configurations, objects, and object orientations.…”