Evidence Against a Constant‐difference Effect in Concurrent‐chains Schedules

Abstract

Savastano and Fantino (1996) reported that in concurrent-chains schedules, initial-link choice proportions remained constant as terminal-link durations increased as long as the subtractive difference between the two terminal-link schedules remained constant. Two experiments with pigeons were conducted to examine this constant-difference effect. Both experiments used equal variable-interval schedules as initial links. The terminal links were fixed delays to reinforcement in Experiment 1 and variable delays to reinforcement in Experiment 2. The durations of the terminal links were varied across conditions, but the difference between pairs of terminal links was always 10 s. In both experiments, preference for the shorter terminal link became less extreme as terminal-link durations increased, so a constant-difference effect was not found. It is argued, however, that this choice situation does not provide clear evidence for or against delay-reduction theory versus other theories of choice.

Escolha Entre Atrasos E Durações Diferentes De Reforço: Sobre a Generalização De Preferências Em Tentativas Discretas Para Um Procedimento De Operante Livre

“…These delay values were used subsequently as the combinations of delays and magnitudes of reinforcement in the terminal links of a concurrent-chains procedure with equal variable-interval schedules in the initial links. It was expected that subjects would show roughly equivalent relative rates in the longer choice period of the free-operant procedure since it has been found that choice tends toward indifference with longer initial links (Fantino, 1969;Mazur, 2002;Wardlaw & Davison, 1974). However indifference estimates derived from the discrete-trials adjusting procedure tended to produce preference for the LLR when the reinforcement parameters were fixed in the procedure with longer initial links.…”

“…The choice period of these procedures is as brief as possible and so the actual delay between response and reinforcement is essentially the same as the scheduled delay. In free-operant procedures the length of the choice period serves as an additional delay that combines with the nominal delay (Mazur, 1987a), and such an additional delay contributes to determine the degree of preference for one alternative (Fantino, 1969;Mazur, 2002;Wardlaw & Davison, 1974).…”

“…and relative values of delays and magnitudes of reinforcer (e.g., Ainslie & Herrnstein, 1981;Grace, 1994;Green & Snyderman, 1980;Mazur, 2002Mazur, , 2004Navarick & Fantino, 1976;Rachlin & Green, 1972;Savastano & Fantino, 1996;Snyderman, 1983). However some differences in preference between subjects are expected when they are tested with the same values of delays and magnitudes, as acknowledged by psychophysics experiments.…”

Stimulus control in fixed interfood intervals

“…Unfortunately, the problem has not received as much research interest as have programs examining behavioral adaptation with increasing experience (Hull, 1943;Rescorla & Wagner, 1972), behavioral adaptation across an unsignaled temporal interval (Gallistel & Gibbon, 2000;Miller & Schachtman, 1985;Spence, 1956), or behavior to concurrently available alternatives (Baum, 1974;Herrnstein, 1970;Mazur, 2002). However, comprehensive principled models that can simultaneously accommodate acquisition, timing, choice, and within-trial events are essential if behavior is to be predicted in a wide variety of situations.…”

Differences and ratios in a nonsymbolic ‘Artificial algebra’: Effects of extended training

“…Questions about whether magnitudes should be scaled linearly or logarithmically may reflect the same fundamental indeterminacy (e.g., Dehaene, 2003;Dehaene, Izard, Spelke, & Pica, 2008;Gibbon & Church, 1981;Tan & Grace, 2012). Models for nonhuman choice behavior have also disagreed about whether differences or ratios of reinforcement-related variables control responding (Mazur, 2002;Savastano & Fantino, 1996).…”