Fixed‐interval Performance and Self‐control in Infants

Abstract

Twenty‐six infants, 3 to 23 months old, were trained on fixed‐interval schedules ranging from 10 s to 80 s. The operant response was touching an illuminated location on a touch‐sensitive screen, and 20 s of cartoon presentation was the reinforcer. The subjects were also trained in a six‐phase self‐control procedure in which the critical phases involved choice between 20 s of cartoon available after a 0.5‐s delay (impulsive choice) and 40 s of cartoon delayed for 40 s (self‐controlled choice). All the youngest children (3 to 5 months) showed long postreinforcement pauses on the fixed‐interval schedule, with most intervals involving the emission of a single, reinforced, response, and all made self‐controlled choices. Older subjects (9 to 23 months) either produced the same pattern as the younger ones on the fixed‐interval schedule (classified as pause‐sensitive subjects) or produced short pauses and higher steady response rates (classified as pause‐insensitive subjects). All pause‐sensitive subjects made self‐controlled choices in the self‐control condition, and all pause‐insensitive subjects made impulsive ones.

Sex-dependent impacts of low-level lead exposure and prenatal stress on impulsive choice behavior and associated biochemical and neurochemical manifestations

“…Hence, the degree of PS-related enhancement observed here appears to be of lesser magnitude than that seen for FI performance, and occurred in males rather than females. These comparative findings underscore the dissociation of FI performance and impulsive choice behavior (Darcheville et al, 1992; 1993), at least in rats, although the two performances were not measured in the same subjects in this study as they were by Darcheville et al The current results, coupled with our prior FI study (Virgolini et al, 2008), however, again demonstrate clear sex-related differences in response to Pb ± PS and indicate the need to further understand how differences in behavioral contingencies and neurobiology imposed by these factors converge to generate sex differences, findings of import to the development of behavioral interventions.…”

“…Since FI response rates have previously shown to be consistent with impulsive choice behavior in a delay discounting paradigm in both infants and children (Darcheville et al, 1992; 1993), the current study sought to further investigate the potential impacts of Pb ± PS on this behavioral domain using a more direct measure of impulsive choice behavior, i.e., a delay discounting paradigm that has been validated in children diagnosed with ADHD (Marco et al, 2009), and correspondingly, to determine whether PS-induced enhancements of Pb effects as seen on the FI schedule also generalized to delay discounting, another behavior that, like FI performance, is controlled by mesocorticolimbic DA/glutamate systems (Roesch and Bryden, 2011). …”

“…Consistent with this hypothesis, combined low level maternal Pb exposure and PS followed by offspring stress were found to significantly increase rates of responding of female rats on a fixed interval (FI) schedule of food reward, to levels consistent with a higher level of Pb exposure (Virgolini et al, 2008). Notably, increased rates of FI responding have been shown in both infants and children (Darcheville et al, 1992; 1993), to be a surrogate for impulsive choice behavior, defined operationally as preference for immediate small reward over delayed but larger reward.…”

“…Response rates on FI schedules have been shown to directly relate to measures of self-control (impulsivity) in children and in infants (Darcheville et al, 1992; 1993). The current study sought to determine whether enhanced effects of Pb ± PS would therefore be seen in a more direct measure of impulsive choice behavior, i.e., a delay discounting paradigm.…”

Integrating Basic and Applied Research and the Utility of Lattal and Perone's Handbook of Research Methods in Human Operant Behavior

“…Applied researchers who work with persons with developmental disabilities can appreciate the challenges involved and benefit from lessons learned in the laboratory. In addition to the methods reviewed by Weisberg and Rovee-Collier, there are several other informative JEAB papers that describe studies with infants and young children on topics such as delayed reinforcement (Reeve, Reeve, & Poulson, 1993), self-control (Darcheville, Riviere, & Wearden, 1993), and verbal behavior (Bentall, Lowe, & Beasty, 1985).…”