Foraging and spatial memory in pigeons (Columba livia).

In two experiments pigeons were studied as they foraged through a simulated patchy environment. Patches consisted of four circular groupings of feeders placed at different locations within a laboratory room. The properties of these patches varied between experiments. In Experiment 1 all feeders in all patches were baited, but the number of food pellets per feeder varied between patches. In Experiment 2 density of food was varied between patches, with 25%, 50%, 75%, or 100% of the feeders randomly baited. A number of variables that indicated pigeons' patch preferences and their behavior within patches were measured. Pigeons showed strong initial preferences for patches containing larger numbers of pellets per feeder in Experiment 1 but did not show differential preferences for patches varying in food density in Experiment 2. Within patches pigeons visited more feeders in richer patches than in poorer patches, both on initial patch entry and on repeat visits. Although pigeons showed evidence of reference and working spatial memory for patches, both experiments failed to provide evidence for the use of working spatial memory for the positions of visited and unvisited feeders within patches. The implications of these findings for spatial memory and foraging theory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Mental rotation in pigeons (Columba livia)?

Previous research has shown pigeons to be insensitive to the orientation of visual test stimuli both for response latency and for discrimination ratio. Discrimination of stimulus orientation has been more difficult to learn than discrimination of small arbitrary differences between stimuli. This has suggested that the visual processing of pigeons is orientation invariant, which would obviate the need for mental rotation such as is often observed in studies with human subjects. Contrary to previous findings, the current experiment obtained linear effects of orientation on response latency and discrimination ratio, with a go/no-go procedure. Pigeons (Columbia livia) first learned to discriminate among line drawings of similar objects and then were tested with rotated versions of the drawings. The pattern of data is similar to that found in studies of human recognition of rotated objects. One speculative explanation of this finding is the mental rotation of stimuli by pigeons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The oblique effect in pigeons (Columba livia).

The oblique effect—the greater discriminability of lines in the main axes orientation compared with obliquely oriented ones—was investigated in 3 experiments in which pigeons (Columba livia) were trained on 2-choice discrimination tasks. In Experiment 1, the reaction times (RTs) of separate groups of 4 pigeons trained to discriminate between a horizontal and a vertical line were significantly faster than pigeons trained to discriminate between 2 oblique lines. In Experiment 2, pigeons trained to concurrently discriminate between the 2 oblique and the horizontal and vertical lines did not show clear RT differences. However, in Experiment 3, the RT results of the 1st experiment were replicated with pigeons trained as in Experiment 1 but with stimuli consisting of 3 dots aligned along the main axes or obliquely. The results are discussed in terms of response measures, biasing habitats, and greater confusability of oblique lines that is due to these lines being mirror images. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Information processing by pigeons (Columba livia): Incentive as information.

Experiment 1 showed that the Hick-Hyman law (W. E. Hick, 1952; R. Hyman, 1953) described the effects of anticipated reinforcement, a form of incentive, on pigeons' (Columba livia) reaction time to respond to a target spatial location. Reaction time was an approximately linear function of amount of information interpreted as probability of reinforcement, implying that pigeons processed incentive at a constant rate. Experiment 2 showed that the Hick-Hyman law described effects of incentive even when it varied from moment to moment in a serial reaction time task similar to that of M. J. Nissen and P. Bullemer (1987), and processing information about target spatial location modulated absolute reaction time and not rate of processing incentive. The results support mental continuity and provide comparative support for the idea of the economics of information in economic theory about the incentive value of information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Imitation of conditional discriminations in pigeons ( Columba livia).

In the present experiments, the 2-action method was used to determine whether pigeons could learn to imitate a conditional discrimination. Demonstrator pigeons (Columba livia) stepped on a treadle in the presence of 1 light and pecked at the treadle in the presence of another light. Demonstration did not seem to affect acquisition of the conditional discrimination (Experiment 1) but did facilitate its reversal of the conditional discrimination (Experiments 2 and 3). The results suggest that pigeons are not only able to learn a specific behavior by observing another pigeon, but they can also learn under which circumstances to perform that behavior. The results have implications for proposed mechanisms of imitation in animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Representation of serial order in pigeons (Columba livia).

In Experiment 1, 2 groups of pigeons were trained to respond to either a 4-item (A→B→C→D) or 5-item (A→B→C→D→E) list. After learning their respective list, half of the subjects were trained on a positive pair with reinforcement provided when pairs were responded to in the order true to that of the original sequence (4-item: B→C; 5-item: B→D). The remaining subjects were trained on a negative pair with reinforcement provided for responding to the pairs in the order opposite to that learned in the original sequence (4-item: C→B; 5-item: D→B). Subjects in the positive pair condition learned their respective pair faster than did subjects in the negative pair condition. In Experiment 2, after reaching criterion on a 4-item list, subjects received 16 BC probe trials spread across 4 sessions of training. Subjects performed significantly above chance on the probe trials. The performance of our subjects in Experiments 1 and 2 demonstrates that, similar to monkeys, pigeons form a representation of the lists that they learn. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hyperstriatal lesions in pigeons (Columba livia): Effects on retention and perseveration.

Two experiments with 32 pigeons explored the possibility that lesions of avian hyperstriatum, which disrupt reversal learning, might have that effect through a potentiation of the influence of proactive interference. Neither experiment found any evidence to suggest excessive interference in hyperstriatal Ss from preceding training on a position (or color) discrimination or on retention of a color (or position) discrimination, and this was true after both a short (30-min) and a long (6- or 7-day) retention interval. There was, however, evidence of a disturbance, not easily interpreted, in retention following the lesions. There was also convincing evidence, from both experiments, for the disruption by hyperstriatal lesions not only of reversal learning but also of tasks not involving reversals, a disruption that suggests a general tendency to perseverate in hyperstriatal birds. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bayesian analysis of foraging by pigeons (Columba livia).

In this article, the authors combine models of timing and Bayesian revision of information concerning patch quality to predict foraging behavior. Pigeons earned food by pecking on 2 keys (patches) in an experimental chamber. Food was primed for only 1 of the patches on each trial. There was a constant probability of finding food in a primed patch, but it accumulated only while the animals searched there. The optimal strategy was to choose the better patch first and remain for a fixed duration, thereafter alternating evenly between the patches. Pigeons were nonoptimal in 3 ways: (a) they departed too early, (b) their departure times were variable, and (c) they were biased in their choices after initial departure. The authors review various explanations of these data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Head and eye movements in unrestrained pigeons (Columba livia).

Head and eye movements were simultaneously recorded during locomotory and pecking behavior of 4 pigeons, which were trained to traverse a conditioning chamber, with a pecking key and a food dispenser at each end. Each trial involved key pecking, walking, and feeding. Head movements were registered with a skull-mounted miniature accelerometer, and eye movements were recorded with implanted electrooculogram (EOG) electrodes. An almost perfect temporal coordination between head and eye movements was observed during both walking and feeding bouts. During walking, head movements primarily provide retinal image stability, and eye movements support visual scanning. During feeding, head movements mainly subserve the grasping of food items, and eye movements maintain visual fixation on them. Because the eyes are reflexively closed during the middle phase of pecks, the head and eye movements are then under ballistic control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiple-landmark piloting in pigeons (Columba livia): Landmark configuration as a discriminative cue.

Using the landmark-transformation technique, researchers have shown that pigeons (Columba livia) tend to encode a goal location relative to 1 landmark, even when multiple landmarks are in the vicinity of the goal. The current experiments examined pigeons' ability to use configural information from a set of landmarks by making the arrangement of 4 landmarks a discriminative cue to the location of buried seeds. Results showed that pigeons used information from the 3 consistently placed landmarks to search accurately when 1 landmark was displaced. Findings indicate that pigeons are able to search for a goal using information from multiple landmarks instead of just 1 and that landmark use by these birds may be more flexible than previously theorized. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Flexible serial response learning by pigeons (Columba livia) and humans (Homo sapiens).

Experimental tasks designed to involve procedural memory are often rigid and unchanging, despite many reasons to expect that implicit learning processes can be flexible and support considerable variability. A version of the serial response time (SRT) task was developed, in which the locations of targets were probabilistically determined. Targets appeared in locations according to both a structured sequence and a cue validity parameter, and the time to respond to each target was measured. Pigeons (Columba livia) and humans (Homo sapiens) both showed response time facilitation at the highest tested value for cue validity, and the magnitude of that facilitation gradually weakened as cue validity was decreased. Both species showed evidence that response times were largely determined by the local predictabilities of individual cue locations. In addition, humans showed some evidence that explicit knowledge of the sequence affected response times, specifically when cue validity was 100%. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Discrimination of duration ratios by pigeons (Columba livia) and humans (Homo sapiens).

Humans were trained on 2 versions of a 2-alternative, forced-choice procedure. First, Ss judged which of 2 successive stimulus durations was longer. Second, Ss judged whether the ratio of the 2 durations was less or greater than a criterion ratio (e.g., 2:1). Accuracy was significantly lower for the task in which the judgment was made according to the ratio of the 2 durations. This result is different than that obtained by J. G. Fetterman et al (1989), who trained pigeons on a similar pair of tasks and found that pigeons' performance was comparable for the 2 discriminations. Comparisons of the pigeon and human data suggest that humans were more accurate than pigeons when the judgment involved which duration was longer, but that accuracy was comparable for the ratio-based task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Symbolic communication" between two pigeons (Columba livia) without unconditioned reinforcement.

Investigated whether nonhuman organisms can be conditioned to respond discriminatively to abstract features of their environments without unconditioned reinforcement. Two experimentally naive male Birmingham rollers were used as Ss. The procedures of this study replicate parts of the study by R. Epstein et al (see record 1981-07163-001), but with some significant variations. Ss were referred to as "mander" and "tacter" from the beginning of the experiment, even though they met the requirements for manding and tacting only later in the proceedings. The mander and tacter were conditioned in the right and left chambers, respectively. Letters or colors were projected onto individual panels for each S. Results show that 2 pigeons can be conditioned to maintain an interaction in which one pigeon has access to a discriminative stimulus that the other needs in order to emit a reinforced response and responds in the absence of deprivation, aversive stimulation, and unconditioned reinforcement. This finding adds to the class of variables heretofore demonstrated to maintain "symbolic repertoires" and highlights a fresh paradigm for conditioning other spontaneous interactions between and within nonhuman species. The importance of social stimuli in such interchanges is demonstrated. (7 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Associative influence on the foraging behavior of pigeons (Columba livia).

In laboratory simulations of foraging conditions, adult White Carneaux pigeons maintained ad lib weight by treadlepressing for lengthy periods of access to grain in a 24-hr live-in environment. Localized visual signals produced by treadlepressing evoked approach and pecking behavior if they signaled impending food presentation (Pavlovian 1st-order conditioning) or the presentation of an established signal for food (Pavlovian 2nd-order conditioning). Findings from the 2 studies imply a role for associative mechanisms in the control of foraging. (44 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orientation invariant pattern recognition by pigeons (Columba livia) and humans (Homo sapiens).

The orientation invariance of visual pattern recognition in pigeons and humans was studied using a conditioned matching-to-sample procedure. A rotation effect, a lengthening of choice latencies with increasing angular disparities between sample and comparison stimuli, was replicated with humans. The choice speed and accuracy of pigeons was not affected by orientation disparities. Novel mirror-image stimuli, rotation of sample shapes, a delayed display of comparison shapes, and a mixed use of original and reflected sample shapes did not lead to a rotation effect in pigeons. With arbitrarily different odd comparison shapes, neither humans nor pigeons showed a rotation effect. Final experiments supported the possibility that the complete absence of a rotation effect in pigeons is because they are relatively better than humans at discriminating mirror-image shapes compared with arbitrary shapes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of reinforcement in spaced-trial operant learning in pigeons (Columba livia).

The author designed 3 experiments to study pigeons' adjustment to unexpected shifts in reinforcer magnitude with a single trial per day. Extinction was faster or poorer after training with a small magnitude (1 food pellet) than after training with a large magnitude (10 or 15 pellets). A shift from 15 to 1 pellet was accompanied by a gradual adjustment, with no indication of a successive negative contrast effect. Pigeons discriminated the reinforcer magnitudes but yielded no evidence of spaced-trial simultaneous negative contrast. Moreover, extinction was faster for a stimulus paired with 1 pellet than for a stimulus paired with 15 pellets. The results can be interpreted in terms of simple strengthening-weakening learning rules and without reference to anticipatory frustration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Degree of representation of the matching concept in pigeons (Columba livia).

In Experiment 1, 12 pigeons (Columba livia) were trained on a simultaneous matching-to-sample task with 2 stimuli and then tested with 2 novel stimuli. Half of the birds were trained with a fixed ratio schedule requirement of 1 (FR1) or 20 (FR20) pecks on the sample stimulus. None of the birds showed any evidence of concept-mediated transfer. In Experiment 2, 12 pigeons were trained with 3 stimuli and then tested with the same novel stimuli used in Experiment 1. Half of the birds in each group were trained with either an FR1 or FR20 requirement on the sample stimulus. Two of the FR20 birds showed high levels of transfer to the novel stimuli similar to that of monkeys in a previous study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The discrimination of natural movement by budgerigars (Melopsittacus undulates) and pigeons (Columba livia).

Three experiments examined the ability of birds to discriminate between the actions of walking forwards and backwards as demonstrated by video clips of a human walking a dog. Experiment 1 revealed that budgerigars (Melopsittacus undulates) could discriminate between these actions when the demonstrators moved consistently from left to right. Test trials then revealed that the discrimination transferred, without additional training, to clips of the demonstrators moving from right to left. Experiment 2 replicated the findings from Experiment 1 except that the demonstrators walked as if on a treadmill in the center of the display screen. The results from the first 2 experiments were replicated with pigeons in Experiment 3. The results cannot be explained if it is assumed that animals rely on static cues, such as those derived from individual postures, in order to discriminate between the actions of another animal. Instead, this type of discrimination appears to be controlled by dynamic cues derived from changes in the posture of the demonstrators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Serial learning with a wild card by pigeons (Columba livia): Effect of list length.

Pigeons (Columba livia) learned 3-, 4- or 5-item lists prior to subset and wild card tests. On the latter, a novel item replaced 1 of the list items. Pigeons who learned 3-item lists responded accurately on all subset pairs (AB, BC, and AC) and on all types of 3-item wild card trials (WBC, AWC, & ABW). Pigeons who learned 4- and 5-item lists responded at chance levels of accuracy on all subsets that did not contain a start or an end item (BC, BD, & CD, respectively, on 4- and 5-item subset tests). On wild card trials, they exceeded chance levels of performance only when the wild card replaced the last item (ABCW & ABCDW trials). Monkeys (Cebus apella) trained to produce a 5-item list perform accurately on all subsets and wild cards. (M. R. D'Amato & M. Colombo; see PA Vols 75:19198 and 77:9086). These differences provide strong evidence that pigeons and monkeys form qualitatively different representations of lists containing four or more items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rapid acquisition of a novelty versus familiarity concept by pigeons (Columba livia).

Pigeons performed a successive discrimination task in which responding to novel slides was rewarded, and responding to familiar slides, seen once previously, was not rewarded. In Experiment 1, naive Ss initially responded more rapidly to familiar slides, but all Ss learned to respond more rapidly to novel slides within a few sessions. In Experiment 2, Ss transferred immediately to novel trial sequences. Experiment 3 showed that both increased retention intervals and interpolated slide presentations impaired recognition. Experiment 4 showed that Ss treated duplicate slides as familiar and confirmed that Ss were using a "novelty versus familiarity" concept. The authors conclude that such a concept is readily available to pigeons. (PsycINFO Database Record (c) 2010 APA, all rights reserved)