The influence of landmark stability on control by occasion setters

In an operant serial feature-positive procedure, an occasion setter (OS_X) signals that a response will be reinforced in the presence of a second stimulus (e.g., a discriminative stimulus, A). During a transfer test, the OS is paired with a different discriminative stimulus. Experiment 1a tested transfer effects in a touchscreen-based spatial occasion setting task with pigeons. During training, four OSs (OS_W, OS_X, OS_Y, and OS_Z) were paired on separate trials with landmark A (LM_A) or B (LM_B) and the opportunity for a reinforced response at one location to the immediate left (R₁) or right (R₂) of the LM (OS_W→LM_A:R₁, OS_X→LM_A:R₂, OS_Y→LM_B:R₁, OS_Z→LM_B:R₂). Training also included non-reinforced trials of LM_A and LM_B alone (LM_A- and LM_B-) and trials of a non-modulated LM with R₁ and R₂ reinforced across separate trials (LM_C:R₁ and LM_C:R₂). After training, the number and spatial location of responses during test trials of a LM paired with the same OS as in training did not differ reliably from transfer tests of an OS paired with a different, modulated LM (OS_W→LM_B and OS_Y→LM_A), but did differ from transfer to the non-modulated LM (OS_X→LM_C). Experiment 1b utilized the same pigeons and training with LM_B to test the degree to which the spatial stability of a LM influenced transfer. Retraining with LM_A was intended to establish it as a non-modulated, stable LM (LM_A:R₂). Subsequent tests with LM_A revealed reduced modulation by the formerly trained OS (OS_W), and complete disruption of modulation of spatial location during transfer with a different OS (OS_Y). These findings further our understanding of the conditions under which OSs may develop and transfer modulation.