Rats (Rattus norvegicus) and pigeons (Columbia livia) are sensitive to the distance to food, but only rats request more food when distance increases

Abstract

Three experiments investigated foraging by rats and pigeons. In Experiment 1, each response on a manipulandum delivered food to a cup, with the distance between the manipulandum and the cup varying across conditions. The number of responses made before traveling to collect and eat the food increased with distance for rats, but not for pigeons. In Experiment 2, two manipulanda were placed at different distances from a fixed food source; both pigeons and rats preferentially used the manipulandum closest to the food source. Experiment 3 was a systematic replication of Experiment 1 with pigeons. In different conditions, each peck on the left key increased the upcoming hopper duration by 0.5, 1.5 or 2.5 s. Completing a ratio requirement on the right key of 1, 4, 8, 16 or 32 pecks, depending on the condition, then produced the food hopper for a duration that depended on the number of prior left pecks. As the ratio requirement increased on the right key, pigeons responded more on the left key and earned more food. Overall, the results replicate previous research, underlining similarities and differences between these species. The results are discussed in terms of optimal foraging, reinforcer sensitivity and delay discounting.

The role of temporal intervals on reinforcer accumulation

“…Each response on either lever produced one food pellet in the unoccupied hub; thus there was only an outbound travel requirement from the response lever to the receptacle. The results replicated the positive relation between reinforcer accumulation and travel distance (Killeen ; McFarland & Lattal ; Reilly et al, ). This finding suggests that the individual components of the response chain of traveling to and from the food receptacle may be isolated for study without sacrificing the general phenomenon.…”

“…In most instances, the number of reinforcers accumulated was an increasing function of lever–receptacle distance, with the highest average pellets accumulated per trial (between 4 and 12 pellets) in the condition with the longest travel requirement. Similar spatial investigations between the response lever and food receptacle replicated this positive relationship between pellets accumulated and travel distance (McFarland & Lattal ; Reilly et al, ).…”

“…To offset cost of travel, accumulation would be expected to increase as the travel or the temporal requirement was increased. This prediction has largely been supported via the distance, time and lever press ratio manipulations (Killeen, ; Killeen & Riggsford, ; McFarland & Lattal, ; Reilly et al, ). The present results also generally support this interpretation in the delay conditions, but there was less accumulation during the ITI conditions despite the fact that accumulation led to larger increases in reinforcer rate in the ITI conditions (see Fig.…”

Bidding for delayed rewards: Accumulation as delay discounting, delay discounting as regulation, demand functions as corollary

“…The average number of feeder operations accumulated on a trial when their collection required traversing the distance given by the abscissae, as reported by Reilly et al (). The symbols are original and replication data, with regressions (Eq.…”

Spatial discrimination reversal and incremental repeated acquisition in adolescent and adult BALB/c mice

“…7, in which adolescent accuracy in link two (back lever response) was poor and showed little improvement across sessions compared to links one and three (front right and left responses, respectively). Insofar as adolescents demonstrate steepened delay of reinforcement gradients, such response demands have the potential to steepen those gradients (Reilly et al, 2012). …”