PIGEONS EXTRACT REDUNDANT, MULTIPLE FEATURES AND ATTEND TO MULTIPLE CONTOURS WHEN RECOGNIZING LINE-DRAWINGS

In a go/no-go procedure, pigeons were trained to discriminate a square line figure (S+) from a circle (S-). Generalization decrements to alt ered versions of S+ were analyzed to determine which features the pige ons attended to. In Experiment 1, the square was broken at midsegments or vertices and expanded by varying amounts in order to determine whi ch of these potential visual features pigeons weight more heavily. Gre ater generalization decrements to midsegment deleted probes than to ve rtex deleted probes provided evidence that pigeons weight midsegments more heavily than vertices. By deleting single vertices or midsegments , selected so as to include all contour elements, Experiments 2 and 3 provided evidence that,. rather than attending to one or a few areas o f contour, most pigeons tend to allocate attention over most or all co ntour elements. In addition, random deletions produced greater general ization decrements than deletions of line segments. The results sugges t that, for simple line drawings, pigeons attend to multiple contours at different locations and may integrate these contours into a represe ntation of an object.