title: Conditional discrimination: the role of CS-alone trials.
abstract: Two experiments examined the role of CS-alone trials in the acquisition of a serial feature positive and negative conditional discrimination. In Experiment 1 the acquisition of an `ambiguous target' discrimination in which a single target cue was reinforced on some trials and nonreinforced on others (P→T+; N→T-) was examined with various sorts of additional target alone training (T+; T-; T+T-; T0). Experiment 2 examined the effects of the same kinds of additional target training trials on the performance of discriminations in which different target cues were presented after the positive feature (P→W+, N→T- trials for group with T+ alone trials) and after negative feature (P→T+, N→W- trials for groups with T+T-; T- and T0 alone trials). The results do not demonstrate an essential role for CS-alone trials in serial conditional discrimination procedures. Implications of the target `ambiguity' and of the proportions of reinforced and nonreinforced trials for the nature of learning in conditional discrimination are discussed.
authors.affiliation: Departamento de Psicologia e Educação-FFCLRP, Universidade de São Paulo, Avenida dos Bandeirantes 3900, 14049-901 Ribeirão Preto, São Paulo, Brazil.
authors.forename: J L
authors.initials: JL
authors.lastname: Bueno
authors.forename: R C
authors.initials: RC
authors.lastname: Moreira