Research on how people perceive human faces has benefited from recent advances in microcomputer technology. The present paper describes techniques that can be used to prepare and present facial stimuli on a Macintosh computer and the advantages of using a computer for preparing and presenting such stimuli.Using a microcomputer to present complex visual stimuli in perception research has become increasingly practical for several reasons: the quality of displays has improved, it is easierto render images into versions that can be manipulated andstored ondiskettes, andthe stimuli can be presented and clearedquickly. There are two additional advantages. First, computerized versions can be modified to achieve effects not available from the original material, and second, the presentation rate makes it possible to collect more data per session. This paper describesthe stepsI used to implement a series of facial perception studies on the Macintosh microcomputer. DIGITIZINGThe first step was to digitize the stimuli. Digitizing is a process that converts a stimulus to one that can be presented andmanipulated by a computer. Thereare many digitizers on the market, andtheyvaryin costandin quality of reproductions. Two relatively inexpensive products are New Image Technology's Magic (Suite 104, 10300 Greenbelt Road, Seabrook, MD 20706) and Thunderware's ThunderScan (21 Orinda Way, Orinda, CA 94563). Magic costs about $400 and includes a digitizer that is used with a video camera. Most video cameras work with it. Magic has the advantage of being able to digitize three-dimensional objects. ThunderScan, a productthatdigitizes two-dimensional objects or pictures, sells for about $230 and includes a scanner that replaces the ribbon of the Imagewriter (a printer for the Macintosh). ThunderScan digitizes pictures rolled into the carriage of the printer. Both of these products can produce images in MacPaint (a graphics editorfor the Macintosh) format. Certain kinds of editing can be done during the digitization process; for example, withThunderScan, one can select either halftone or high-contrast digitizing in order to preserve shading differences or to produce blackand-white images without halftones.The images I used were likenesses derived from the 1960editionof the Identi-Kit facial reproduction system (2100 Roosevelt Avenue, Springfield, MA 01101) used Requests for reprints should be sent to Dean G. Jensen, Department of Psychology, Rice University, P.O. Box 1892, Houston, TX 77251.by law enforcement agencies. The Identi-Kit consists of clearplastic foils thathavea facial feature (i.e., hair, eyebrows,eyes, nose, lips, or chin) on eachfoil. Composite faces are madeby laying the foils on top of one another. Figure 1 wasmade by forming a composite fromthefoils, photocopying it, and then digitizing it.Pages from the Identi-Kit catalogue containing facial features were alsodigitized withThunderScan. This was originally done as a test of the equipment, since the features in the catalogue are considerably smaller than the features on t...

If subjects are given a series of problems that all have the same type of solution, they often have great difficulty with a subsequent problem that would ordinarily be solved very easily. This phenomenon is referred to as psychic blindness or Einstellung. This study explored whether knowledge of the Einstellung phenomenon facilitates problem solving. Eight subjects in each of three experimental conditions were given set-inducing problems followed by an otherwise easy “critical” problem that could not be solved by the strategy used on the set-inducing problems. Subjects in one condition worked on the easy problem without interruption. Subjects in a second condition were interrupted by an unexpected event. Subjects in a third condition were interrupted by a message explaining how the ability to solve an otherwise easy problem could be inhibited after solving a series of problems with more difficult solutions. Subjects given this hint were three times more likely to solve the easy problem than were subjects in the other experimental conditions. Four subjects in the No-Set Control condition all solved the easy problem by the third trial. The implications for training electronics technicians, computer programmers and other problem solvers are discussed.

These experiments explored whether groups of facial features are perceived holistically or independently of one another. This was tested with the speeded classification task on inner (the eyebrows, eyes, nose, and lips) and outer (hair and chin) groups of features. When the inner features were separated, either by grouping the eyebrows or the lips as an outer feature, classifications by the inner group were affected by changes in the outer group although classifications by the outer group were unaffected by changes in the inner group. These results indicate that the outer features are perceived independently of the inner features and that the eyebrows, eyes, nose, and lips are perceived holistically. This implies that for facial reproduction, a change of an inner feature should be followed by the reconsideration of the other inner features in the presence of the changed feature.

Previous research has shown that distractor faces made up of features of previously seen target faces are more likely to be selected as targets than the targets themselves. The present experiments sought to determine whether there is a tendency to pick a face out of a lineup if the face is more similar to the other lineup members than they are to each other. In Experiment 1, 25 subjects ranked members of lineups on similarity to target faces. The important comparisons were between rankings of the faces similar to the distractors (the critical faces), target faces, and other distractors. When the target faces were present in the lineup, no significant difference between rankings of the targets and the critical faces was found. When no targets were present in the lineup the critical faces were judged to be more like the targets than were the other distractors. This latter finding was replicated in Experiment 2 using visual stimuli other than faces. Implications for choosing police lineups are discussed.

Injuries to fingers accounted for the highest proportion of injuries (17%) during a five year period in a large petro-chemical manufacturing complex. The injuries occurred most frequently for those jobs that involve manipulating tools, machinery, and materials. Scenario analyses carried out on the 1223 finger injuries indicated that the most common prior activities were assembling or disassembling equipment (32%) and materials handling (28%), accident events were impact with an object (40%) or a tool that slipped or missed the workpiece (27%), and injury events were being caught between objects (25%), being hit by moving objects (19%), or being cut by objects (13%). Some suggestions for interventions follow from these patterns.