Conditional reinforcers and informative stimuli in a constant environment.

Boutros et al. (2009) worked with pigeons on two keys. Each key paid off on its own variable-interval schedule.

While the birds pecked, extra lights or sounds sometimes appeared. These extras were always paired with food somewhere else.

The room never changed. The question: would these paired extras act like bonus reinforcers and shift the overall choice split?

The paired stimuli nudged momentary bursts of pecking, but the birds’ long-run key preference stayed locked to the food ratio.

In short, local wiggles yes, global swing no.

Alvarez et al. (1998) saw the same birds follow tiny local cues when the background kept shifting. Nathalie’s group held the background still and saw only local blips. Same cues, different context, different power.

Dews (1978) showed that a stimulus paired with food can create local contrast—brief jumps in responding. Nathalie confirms that punch still happens, but adds that the jump stays local when the wider scene never changes.

Sherwell et al. (2014) later built on this idea. They gave brief extra cues right before a schedule flip and found sharper timing. Together the papers say: stimuli help only when they carry news; in a frozen world they are just decoration.

If your session room is stable, don’t expect a “good job” ticket to reshape broad choice. Use the ticket to steer tiny moment-to-moment moves instead, or change the backdrop so the ticket carries real news.