THE COURSE OF ACQUISITION OF A LINE‐TILT DISCRIMINATION BY RHESUS MONKEYS¹

Abstract

Each of four groups of monkeys were trained on a different simultaneous discrimination procedure involving a vertical line as the correct choice. Each group, after acquiring the discrimination, was tested for generalization along the dimension of line tilt. Monkeys that learned to select the vertical line when the alternative choices were distinguished from the correct choice by two aspects (brightness and absence of line) showed almost complete tilt generalization (flat gradient). Monkeys that learned to select the line when the alternatives were distinguished only by the absence of the line showed poor tilt discrimination (generalization gradient slightly peaked at vertical). Monkeys developed a good tilt discrimination when nonvertical lines were gradually introduced by progressively darkening them on the previously blank alternatives. Monkeys developed a tilt discrimination with the lowest error rate when only horizontal alternatives were gradually introduced and then pairs of alternatives progressively closer to vertical were made available.

SELECTIVE ATTENTION: THE EFFECTS OF COMBINING STIMULI WHICH CONTROL INCOMPATIBLE BEHAVIOR1

“…Ray, 1967) currently being developed. The experiment was designed to define stimulus control only in terms of discrimination performance, so the lengthy details of the initial training program are omitted.…”

“…Ray, 1967), black vertical and horizontal lines on a white background. The lines, when projected onto the keys, were 1.5 in.…”

Stimulus delay and the reduction of errors in the transfer of stimulus control

“…These (Moore & Goldiamond, 1964;Touchette, 1968), as well as for a variety of animal Ss (Ray, 1967;Schusterman, 1966;Westbrook & Miles, 1970) and the training sequence in each of these procedures has required the S to respond to a compound stimulus. These transfer programs, along with Terrace's (1963b), share the disadvantage that the point in the training sequence by which the to-be-transferred-to stimulus dimension has acquired stimulus control remains procedurally elusive.…”

The role of the mirror-image reversal effect in reducing the peak shift and area shift along the angularity dimension

“…The peak shift is quite pervasive, having been demonstrated along the dimensions of line tilt with pigeons (Bloomfield, 1969) and monkeys (Ray, 1967); wavelength with pigeons (Hanson, 1959), goldfish (Yarczower & Bitterman, 1965), and humans (Doll & Thomas, 1967); floor position with pigeons (Riccio, Urda, & Thomas, 1966) and rats (Lyons, Klipec, & Eirick, 1973); and with auditory stimuli, using rats (Pierrel & Sherman, 1960). Nonetheless, the majority of peak-shift studies in the literature have used pigeons and the dimensions of either angularity or wavelength.…”