Sign- versus goal-tracking: effects of conditioned-stimulus-to-unconditioned-stimulus distance.
Spatial gap between signal and food decides whether learners stay at the signal or go to the food site.
01Research in Context
What this study did
The team worked with pigeons in a small lab chamber.
A white key light came on for a few seconds.
Grain followed right after the light, but the grain hopper sat at different distances from the key.
The researchers watched whether the birds pecked the key light or walked to the grain site.
What they found
When the grain hopper sat close to the key, birds pecked the key hard.
When the hopper sat far away, birds stopped pecking the key and walked straight to the hopper.
At middle distances both responses showed up at once.
The birds switched styles based on how far the food was from the signal.
How this fits with other research
Stevenson (1966) already showed that spacing test stimuli changes how pigeons spread their responses.
The new study adds that spacing between signal and food also changes what the bird aims for.
Sainsbury (1971) found that packing display elements close together helps pigeons learn what NOT to peck.
Together the papers say the same rule: distance between cues controls which cue wins.
Why it matters
Your client may approach the wrong item if reinforcers sit far from the SD.
Place the reward close to the discriminative stimulus to keep pointing, touching, or looking at that stimulus.
If you need the learner to move, put the reward farther away and watch the shift happen naturally.
Want CEUs on This Topic?
The ABA Clubhouse has 60+ free CEUs — live every Wednesday. Ethics, supervision & clinical topics.
Join Free →Move the reinforcer within 10 cm of the target stimulus to lock in stimulus-directed responses.
02At a glance
03Original abstract
Three pigeons were exposed sequentially across experimental phases to five different distances between the conditioned stimulus and the site of the unconditioned stimulus in a sign-/goal-tracking procedure. A computer-controlled tracking system provided a continuous record of the bird's position by continuously monitoring the location of the bird's head in three-dimensional space. It was found that birds sign-tracked (i.e., approached the conditioned stimulus) when the conditioned stimulus was closest to the site of the unconditioned stimulus, goal-tracked (i.e., approached the site of the unconditioned stimulus in the presence of the conditioned stimulus) when the conditioned stimulus was farthest from the site of the unconditioned stimulus, and engaged in both sign- and goal-tracking (or something intermediate) at intermediate conditioned-stimulus-to-unconditioned-stimulus distances. When both sign- and goal-tracking occurred, the former tended to occur in the first half and the latter in the second half of the interval in which the conditioned stimulus was present. The results suggest (a) whether sign- or goal-tracking (or both) occurs is a function of the distance of the conditioned stimulus from the site of the unconditioned stimulus, (b) the fact that pigeons but not rats have been found to sign-track consistently throughout the duration of the conditioned stimulus may be due to quantitatively rather than qualitatively different effects of conditioned-stimulus-to-unconditioned-stimulus distance across species (i.e., a "short" conditioned-stimulus-to-unconditioned-stimulus distance for a pigeon may be a "long" one for a rat), and (c) sign- and goal-tracking may be competing behavioral tendencies that can (e.g., at intermediate conditioned-stimulus-to-unconditioned-stimulus distances) cancel each other out. The findings lend support to theories that specify an interaction between phylogenetic and reinforcement variables in determining whether sign- or goal-tracking will occur in any given experimental preparation.
Journal of the experimental analysis of behavior, 1992 · doi:10.1901/jeab.1992.57-17