Hungry Pigeons Research Articles

Hungry pigeons prefer sooner rare food over later likely food or faster information.

Making decisions and investing effort to obtain rewards may depend on various factors, such as the delay to reward, the probability of its occurrence, and the information that can be collected about it. As predicted by various theories, pigeons and other animals indeed mind these factors when deciding. We now implemented a task in which pigeons were allowed to choose among three options and to peck at the chosen key to improve the conditions of reward delivery. Pecking more at a first color reduced the 12-s delay before food was delivered with a 33.3% chance, pecking more at a second color increased the initial 33.3% chance of food delivery but did not reduce the 12-s delay, and pecking more at a third color reduced the delay before information was provided whether the trial will be rewarded with a 33.3% chance after 12 s. Pigeons' preference (delay vs. probability, delay vs. information, and probability vs. information), as well as their pecking effort for the chosen option, were analyzed. Our results indicate that hungry pigeons preferred to peck for delay reduction but did not work more for that option than for probability increase, which was the most profitable alternative and did not induce more pecking effort. In this task, information was the least preferred and induced the lowest level of effort. Refed pigeons showed no preference for any option but did not drastically reduce the average amounts of effort invested. These results are discussed in the context of species-specific ecological conditions that could constrain current foraging theories.

Indoor Animals

Indoor Animals Noah Bogdonoff (bio) Science Fiction A deer arrives for you in a yellow PT Cruiser. A woman slides out of the atrocious car, her face sun-freckled, her hair sun-bleached. She is no-nonsense about this deer. She says that she found him next to his mother, who was dead by the side of the road, and that the wildlife rescue centers would not take in a baby deer because deer are too common to protect. She says that she has already named the deer; his name is Star Wars. He is no more than five days old. Will you take him, she asks. You consider that your dog is named Han Solo and your car is called the Millennium Falcon. It feels momentarily like a collapse of reality: the molecule is smaller and more fragile than the atom. And then Star Wars mews from the blazing-hot cruiser. Eeeeee, he says. Eeee. He is hungry and very cute. Of course, you tell the woman. Of course we will take the deer. Thank god, she says, as you approach the PT Cruiser and lift the leggy, terrified creature from the car. Thank god, says the lady again. You are a saint. And then she drives off, and you realize as she peels away that you forgot to ask her who she was and how she knew that you would be the kind of loony to accept an orphaned deer. Eee, says Star Wars. You do not know how to raise a baby deer. You know nothing about baby deer. For starters, you do not know how to keep the dog from eating him. You also do not know what baby deer eat, or how often. The Internet in your house is spotty; today it refuses to tell you anything. You have a friend who is a bovine nutritionist, however, so you call him on the telephone and he gives you instructions, as well as a warning: do not name this baby deer, because he is going to die of hunting as soon as he has antlers. His name is Star Wars, you tell the bovine nutritionist. Now that's some fucked up shit, he says. Superstition: Pigeons The psychologist B. F. Skinner conducted an experiment which involved starving caged pigeons. The hungry pigeons were taught to operate a one-button machine: press the button and a door opens to reveal food. The pigeons learned [End Page 42] the machine easily; they used it often and became less hungry. Skinner starved his pigeons again. This time, he did not give them a button to press. Instead, he opened the door at random. He wanted to see what the pigeons would do when they were not in control. The pigeons did not understand. They were caged; they knew only rules, causality. They still believed, in the way that pigeons believe, that they were responsible for causing the door to open. One by one, each pigeon began to fixate on whatever motion it happened to be making when Skinner opened the door. One pigeon squatted up and down endlessly. Another flapped its wings in a specific pattern. Another simply blinked at the door faithfully. This time, they believed, this squat, this flap, this blink, this time the door will open. Skinner never let his pigeons die of starvation, but he also never let them in on the secret. Cohabitation It goes like this: you lie down, and then the fawn lies down. You roll over—slowly—and turn the lights off. You close your eyes and wait. The fawn gets up. His baby hooves clip-clop against the floorboards. He nestles his face into your face. He sucks on your ear for a moment, expecting milk. He trots to the far side of the room. As you drift off to sleep, you hear the hiss of a distant tributary, the trickle of a nearby stream. You are not asleep; there is no stream. The fawn is peeing, steadily and unabashedly, all over the floor. It happens like this every night. Strangers You take a walk through the hunting grounds. There are no hunters...

Less means more for pigeons but not always

When humans are asked to judge the value of a set of objects of excellent quality, they often give this set higher value than those same objects with the addition of some of lesser quality. This is an example of the affect heuristic, often referred to as the less-is-more effect. Monkeys and dogs, too, have shown this suboptimal effect. But in the present experiments, normally hungry pigeons chose optimally: a preferred food plus a less-preferred food over a more-preferred food alone. In Experiment 2, however, pigeons on a less-restricted diet showed the suboptimal less-is-more effect. Choice on control trials indicated that the effect did not result from the novelty of two food items versus one. The effect in the less-food-restricted pigeons appears to result from the devaluation of the combination of the food items by the presence of the less-preferred food item. The reversal of the effect under greater food restriction may occur because, as motivation increases, the value of the less-preferred food increases faster than the value of the more-preferred food, thus decreasing the difference in value between the two foods.

Hungry pigeons make suboptimal choices, less hungry pigeons do not

Hungry animals will often choose suboptimally by being attracted to reliable signals for food that occur infrequently (they gamble) over less reliable signals for food that occur more often. That is, pigeons prefer an option that 50 % of the time provides them with a reliable signal for the appearance of food but 50 % of the time provides them with a reliable signal for the absence of food (overall 50 % reinforcement) over an alternative that always provides them with a signal for the appearance of food 75 % of the time (overall 75 % reinforcement). The pigeons appear to choose impulsively for the possibility of obtaining the reliable signal for reinforcement. There is evidence that greater hunger is associated with greater impulsivity. We tested the hypothesis that if the pigeons were less hungry, they would be less impulsive and, thus, would choose more optimally (i.e., on the basis of the overall probability of reinforcement). We found that hungry pigeons choose the 50 % reinforcement alternative suboptimally but less hungry pigeons prefer the more optimal 75 % reinforcement. Paradoxically, pigeons that needed the food more received less of it. These findings have implications for how level of motivation may also affect human suboptimal choice (e.g., purchase of lottery tickets and playing slot machines).

Complex dynamic processes in sign tracking with an omission contingency (negative automaintenance).

Hungry pigeons received food periodically, signaled by the onset of a keylight. Key pecks aborted the feeding. Subjects responded for thousands of trials, despite the contingent nonreinforcement, with varying probability as the intertrial interval was varied. Hazard functions showed the dominant tendency to be perseveration in responding and not responding. Once perseveration was accounted for, a linear operator model of associative conditioning further improved predictions. Response rates during trials were correlated with the prior probabilities of a response. Rescaled range analyses showed that the behavioral trajectories were a kind of fractional Brownian motion.

Assessment of drug state dimensionality via drug-drug training and stimulus generalization testing

A procedure for determining whether different drugs share a common stimulus dimension is described. This procedure uses the presence of post-discrimination generalization gradient asymmetry as an indication that the training stimuli lay along a common stimulus dimension. Separate groups of hungry pigeons were trained to discriminate a 15 mg/kg dose of phenobarbital which was associated with frequent food reinforcement (S+) from each of 9 different drug conditions which were associated with infrequent reinforcement (S-). S- stimuli were selected to represent a drug from a completely different class (amphetamine), a drug with biphasic effects which may partially correspond with the effects of phenobarbital (delta 9-THC), and a drug from the same class as the S+ (pentobarbital). Following discrimination training subjects were tested for generalization to five dosage levels (5, 10, 15, 20, 25 mg/kg) of phenobarbital. Steep symmetrical generalization gradients around the S+ indicated that delta 9-THC and d-1-amphetamine were both quite discriminable from phenobarbital, and that they were perceived by subjects as representing stimulus dimensions different from phenobarbital, and that it was perceived as lying on a stimulus dimension common to phenobarbital. This procedure may allow better understanding of how different drug states are perceived by animals as similar or dissimilar.

Pigeons' spatial memory: II. Acquisition of delayed matching of key location and transfer to new locations.

Five hungry pigeons first received delayed matching of key location training. Trials began with a "ready" stimulus (brief operation of the grain feeder). Then one (randomly chosen) of a set of four keys from a three-by-three matrix was lit briefly as the sample. After a short delay (retention interval), the sample key was lit again along with one of the other eight keys. A peck at the key that had served as the sample produced grain reinforcement, whereas a peck to the other key produced only the intertrial interval. After delayed matching of key location was learned, the remaining five key locations were introduced as samples. Four of the five birds performed at considerably above-chance levels on the novel sample trials during the first as well as subsequent sessions. These results suggest that pigeons sometimes learn the single rule-"choose the location that matches the sample." The relevance of these results to the issue of whether pigeons learn a generalized matching rule (i.e., a concept of "sameness") is discussed.

Spatial location of first- and second-order visual conditioned stimuli in second-order conditioning of the pigeon’s keypeck

A keylight (S1) always projected on one response key signaled food for hungry pigeons in a first-order classical conditioning procedure. When S1 evoked strong keypecking, it was presented without food on some of the trials that were signaled by other keylights (S2) in a second-order conditioning procedure. On half the second-order trials, the occurrence of S1 was signaled by an S2 projected on the same response key as S1; on the remaining trials, S1 was signaled by another S2 projected on a different key than S1. Acquisition of keypecking to S2 was faster when S2 and S1 occurred on the same response key than when they occurred on different keys. Asymptotic responding to the two S2s was not different, however. A control group showed that keypecking to S2 on the “different” key resulted from the pairing of S2 on that key with S1 on the other key. The enhancement of acquisition to S2 when it occurs in the same location as S1 may reflect the effects of stimulus similarity on conditioning, or, simply, a more optimal temporal relationship between S2 and S1. The fact that directed motor behavior can be established to a stimulus in one location solely through pairing of that stimulus with a well-conditioned stimulus in another location further implicates second-order conditioning as a factor in conditioned reinforcement effects in instrumental training.

CONDITIONING OF TWO‐RESPONSE PATTERNS OF KEY PECKING IN PIGEONS1

On discrete trials, two response keys were made available to hungry pigeons and food reinforcement depended on the order in which the required two key pecks occurred. In different phases, only one of the four possible two-peck sequences (left-left, left-right, right-left, and right-right) produced food reinforcement. In each case, the pigeons learned to perform the correct two-peck sequence more often than the incorrect sequences. Furthermore, the course of differentiation mastery indicated that both reinforcement history and response-reinforcer contiguity influenced performance. These results reveal that response patterns comprising two instances of the same response left-left and right-right) or instances of two different responses (left-right and right-left) may function as operants, thereby extending the generality of conditioning principles from discrete responses to structured sequences of behavior. These and other results are discussed in terms of contiguity-based and memory-based models of learning.

Association of conditioned stimuli during serial conditioning by pigeons

CS2-CS1-US autoshaping was given to hungry pigeons and evidence of CS2-CS1 association was sought. Pigeons pecked that key of a two-key compound CS2 located where the upcoming CS1 key light was to occur. Such CS2-CS1 association was: (1) quickly acquired, (2) quite durable, and (3) stronger with simultaneous than with successive discrimination tasks.

CONDITIONING OF WITHIN‐TRIAL PATTERNS OF KEY PECKING IN PIGEONS1

The possibility of conditioning systematic patterns of responding during brief discrete trials was studied by requiring hungry pigeons to key peck and then pause or to pause and then key peck in order to gain access to food. These schedules were highly effective in promoting decelerated and accelerated rates of responding, respectively, within individual trials; indeed, performance was quite similar to that observed when explicit external stimuli were correlated with "peck" and "pause" portions of the daily trials. Finally, schedules of reinforcement that did not selectively reinforce peck-pause or pause-peck patterns neither generated these patterns nor maintained them at the previous high levels. The results, therefore, confirm Shimp's (1976) proposal that organized groupings of discrete responses may function as operants-even in the absence of strict response-reinforcer contiguity.

MATCHING‐BASED HEDONIC SCALING IN THE PIGEON

Four slightly hungry pigeons chose between pairs of grains in a Findley concurrent choice procedure. For Condition I, choice involved hemp versus buckwheat; for Condition II, wheat versus buckwheat; and for Condition III, hemp versus wheat. In all conditions, frequency of reinforcement was arranged according to concurrent variable-interval variable-interval schedules. On the assumption that subjects matched their behavior and time distributions to those of reinforcer value, the choice functions obtained in Conditions I and II were transformed to yield estimates of values of hemp and wheat relative to buckwheat. These, in turn, provided predictions about behavior and time allocation in Condition III. In general, the predicted outcomes were close to those actually obtained. The results evidence the effectiveness of matching-based hedonic scales in the prediction of choice between qualitatively different reinforcers.

DIFFERENTIAL AUTOSHAPING TO COMMON AND DISTINCTIVE ELEMENTS OF POSITIVE AND NEGATIVE DISCRIMINATIVE STIMULI1

The learning by hungry pigeons of a discrimination between two successively presented compound visual stimuli was investigated using a two-key autoshaping procedure. Common and distinctive stimulus elements were simultaneously presented on separate keys and either followed by food delivery, S+, or not, S-. The subjects acquired both between-trial and within-trial discriminations. On S+ trials, pigeons pecked the distinctive stimulus more than the common stimulus; before responding ceased on S- trials, they pecked the common stimulus more than the distinctive one. Mastery of the within-display discrimination during S+ trials preceded mastery of the between-trials discrimination. These findings extend the Jenkins-Sainsbury analysis of discriminations based upon a single distinguishing feature to discriminations in which common and distinctive elements are associated with both the positive and negative discriminative stimuli. The similarity of these findings to other effects found in autoshaping-approach to signals that forecast reinforcement and withdrawal from signals that forecast nonreinforcement-is also discussed.

Learning by Following a Food Source

Hungry pigeons first learned to eat grain from the experimenter's hand. When the hand approached and "pecked" a small disk to produce grain in a food hopper, the pigeons followed the hand rapidly learned to peck the disk. Birds given operant conditioning training took significantly longer to learn the same response. Under natural conditions, young animals may learn to behave like their parents simply by following parental sources of food.

A note on the negative automaintenance procedure

Some experiments have reported that illumination of a response key prior to grain presentation to hungry pigeons establishes high levels of pecking on the lighted key despite a negative correlation between pecks and presentation of grain. Initial attempts to employ this “negative automaintenance” procedure resulted in very low levels of pecking, but pecking developed and was maintained at a high level in all pigeons when the chamber illumination, the trial length, and the intertribal interval were adjusted.