Monocular and binocular intensity thresholds for fields containing 1-7 dots.

The discrimination of dot patterns as a function of number and average separation of dots.

“…In the present task S compares each pattern with another almost identical to it. The task of differentiation, on the other hand, would require learning a different response for each of a num- 1 It should be remembered that an "S" error is actually a "D" response on an "S" trial and vice versa. The kind of error was defined by the physical identity or dissimilarity of the patterns compared on that trial.…”

“…A search of the literature revealed few similar attacks on this problem of pattern discrimination. However, a considerable number of recent research studies have dealt with the general problem of the discrimination of visual number, e.g., Hunter and Sigler (2), Taves (7), Saltzman and Garner (6), Kaufman, Lord, Reese, and Volkmann (3), and Casperson and Schlosberg (1). Typically, the task is that of viewing a collection of dots or similar elements and indicating the number present.…”

Process of enumeration.

“…One approach to the span-of-apprehension idea is as detection of a number of targets (Casperson & Schlosberg, 1950;Restle, Rae, & Kiesler, 1961;Schlosberg, 1948). This approach deals mainly with perception of a number of dots under short exposures or poor illumination, but may undermine the concept of a "magical number."…”

Comment

“…Sometimes two eyes act independently (Pirenne,1943;Woodworth & Schlosberg, 1954, pp. 398-399), but sometimes they do not (Casperson & Schlosberg, 1950; reviews of binocular depth perception, e.g., Woodworth & Schlosberg, 1954, pp. 455-491).…”