Ambiguous-cue Problem Research Articles

Pigeons and the Ambiguous-Cue Problem: A Riddle that Remains Unsolved.

The ambiguous-cue task is composed of two-choice simultaneous discriminations involving three stimuli: positive (P), ambiguous (A), and negative (N). Two different trial types are presented: PA and NA. The ambiguous cue (A) served as an S- in PA trials, but as an S+ in NA trials. When using this procedure, it is typical to observe a less accurate performance in PA trials than in NA trials. This is called the ambiguous-cue effect. Recently, it was reported in starlings that the ambiguous-cue effect decreases when the stimuli are presented on an angled (120°) panel. The hypothesis is that the angled panel facilitates that the two cues from each discrimination are perceived as a compound, precluding value transfer via a second-order conditioning mechanism. In this experiment, we used pigeons and a flat panel. Nevertheless, our data were quite similar to the previous data in starlings. We conclude that the form of the panel cannot explain the ambiguous-cue effect. Several alternatives to be explored in future experiments are suggested. The riddle of the ambiguous-cue problem still remains unsolved.

An Analysis of the Solution of PAN Ambiguous-Cue Problem by Response Latency in Pigeons

An Analysis of the Solution of PAN Ambiguous-Cue Problem by Response Latency in Pigeons

European starlings unriddle the ambiguous-cue problem.

The ambiguous-cue problem is deceptively simple. It involves two concurrently trained simultaneous discriminations (known as PA and NA trials), but only three stimuli. Stimulus A is common to both discriminations, but serves as non-reinforced stimulus (S-) on PA trials and as reinforced stimulus (S+) on NA trials. Typically, animals’ accuracy is lower on PA trials—the ambiguous-cue effect. We conducted two experiments with European starlings (Sturnus vulgaris) using Urcuioli and Michalek’s (2007, Psychon B Rev 14, 658–662) experimental manipulations as a springboard to test the predictions of two of the most important theoretical accounts of the effect: the interfering cue hypothesis and value transfer theory. Both experiments included two groups of birds, one trained with a regular ambiguous-cue problem (Group Continuous) and another trained with partial reinforcement on PA trials (Group PA-Partial). The experiments differed only in the number of sessions (18 vs. 36) and daily trials (360 vs. 60). As previously observed, we found faster acquisition on NA trials than on PA trials in both experiments, but by the end of training PA performance was surprisingly high, such that no ambiguous-cue effect was present in Group Continuous of either experiment. The effect was still present in both PA-Partial groups, but to a smaller degree than expected. These findings are inconsistent with the literature, in particular with the results of Urcuioli and Michalek (2007) with pigeons, and question the aforementioned theoretical accounts as complete explanations of the ambiguous-cue effect. In our view, to achieve such high levels of accuracy on PA trials, starlings must have attended to configural (i.e., contextual) cues, thus differentiating stimulus A when presented on PA trials from stimulus A when presented on NA trials. A post hoc simulation of a reinforcement-based configural model supported our assertion.

Transverse patterning in pigeons

Pigeons were trained to choose between colored lights (A, B, C, and D), first in a two-pair ambiguouscue problem (A+B−, B+C−), and then, with all colors nondifferentially reinforced, in a three-pair loop problem (A+B−, B+C−, C+A−) followed by a four-pair loop problem (A+B−, B+D−, D+C−, C+A−). Systematic efforts were made to simulate the data with a variety of models incorporating one or another of three conceptions of stimulus compounding prominent in the literature on compound conditioning. One conception is that the components of a compound stimulus are altered by interaction; the second is that they are not altered, but only supplemented with a new (compound-unique) component generated in the interaction; and the third is that the components entirely disappear in a configurational transformation. The ambiguous-cue data could be simulated accurately with each of the models, but the loop data with none of them. A convincing explanation of performance in loop problems remains to be found.

Performance of honeybees in reversal and ambiguous-cue problems: Tests of a choice model

Individual honeybees visiting the laboratory regularly for food were trained in a variety of discrimination-reversal and ambiguous-cue problems to choose between two differently scented targets, of which one or the other contained sucrose solution. The training was simulated with a set of equations for predicting choice on the basis of associative strength, and the accuracy of prediction was indexed by the root-mean-square deviation of simulated data from obtained data. Developed earlier on the basis of performance in other problems (Couvillon & Bitterman, 1985), the model proved adequate for the new problems as well.

The ambiguous-cue problem: The effects of reduced similarity between trials and the schedule of reinforcement

In a series of seven experiments pigeons were trained on the two-choice ambiguous-cue problem that contains PA and NA trials. On PA trials choice of P (the positive stimulus) was reinforced and choice of A (the so-called ambiguous stimulus) was not reinforced; on NA trials choice of A was reinforced and choice of N (the negative stimulus) was not reinforced. When the two types of trials were distinguished by only the presence of P or N and each trial was terminated by one response, subjects quickly attained high levels of performance on NA trials but showed only chance levels of performance on PA trials. PA performance was markedly improved when a variety of additional stimuli distinguished the two types of trials and when a variety of schedules of intermittent reinforcement were employed; these manipulations had little effect on NA performance.

Eye movements of monkeys during performance of ambiguous cue problems

Eye movements of four stumptailed monkeys were measured during performance of simple and ambiguous form discriminations. Duration of fixations increased during learning of the simple discrimination, whereas the number of shifts in fixation from one stimulus to the other (scanning) increased and subsequently decreased. The asymptotic levels of scanning in both simple and ambiguous discriminations were consistent with predictions generated by a minimum frequency of observing hypothesis. Duration of fixations other than the last fixation preceding the choice response did not change significantly during performance of an ambiguous cue problem in comparison with the simple discrimination, but duration of the last fixation increased significantly. This result was discussed in terms of altered information processing requirements.

Intermittency of reinforcement during NA trials and performance on the ambiguous-cue problem.

Intermittency of reinforcement during NA trials and performance on the ambiguous-cue problem.

The Ambiguous Cue Problem and the Interfering Cue Theory

Summary The modified interfering cue theory put forward by Fletcher et al. (2) to explain performance in the ambiguous cue problem (ACP) was examined. Eight-year-old children were first trained to acquire response tendencies to the individual cues of this problem. When presented subsequently with the problem, the children showed marked differences in the number and type of errors made. The results were interpreted as supporting the theory of Fletcher et al. It was also suggested that the cues with clear positive or negative values were employed by the subjects to limit or neutralize the interference caused by the ambiguous cue.

A theoretical analysis of the PAN ambiguous-cue problem

The PAN ambiguous-cue problem consists of three stimuli: P, the positive (consistently rewarded) cue; N, the negative (consistently nonrewarded) cue; and A, the ambiguous cue which is negative (nonrewarded) when paired with P, but positive (rewarded) when paired with N. This paper demonstrates how the finding of superior performance on the NA trials as compared to the PA trials (with stereometric objects) can be rigorously derived from a recent extension of Hull-Spence discrimination learning theory, the Stimulus Interaction Hypothesis. It is also shown how this theory can account for the converse outcome of better performance on PA than on NA trials when planometric plaques are used as stimuli. Finally, alternative explanations of the findings are described and evaluated.

Reinforcement of ambiguous-cue problem performance under various across trial fixed-ratio schedules

Two pigeons were trained on the two-choice ambiguous-cue problem that contained two types of trials. On PA trials, choice of P (the positive stimulus) is reinforced and choice of A (the ambiguous stimulus) is not reinforced; on NA trials, choice of A is reinforced and choice of N (the negative stimulus) is not reinforced. Under the various across-trial fixed-ratio (FR) schedules of reinforcement, NA performance remained superior to PA performance. PA performance was poorer under FR 12 than FR 1; NA performance, however, was not affected by the size of the FR. Similarly, only PA performance showed any change as a function of the trial’s location within the ratio—it was poorest early in the ratio.

Performance of the pigeon on the ambiguous-cue problem

Three pigeons were trained on the two-choice ambiguous-cue problem which involves three stimuli: a positive stimulus, to which responding is always reinforced, a negative stimulus, to which responding is never reinforced, and an ambiguous stimulus, to which responding is sometimes reinforced and sometimes not reinforced, depending on which of the other stimuli is simultaneously presented. Using distinctively colored stimuli, all Ss quickly learned to choose the ambiguous stimulus when it was paired with the negative stimulus. Ss also learned, although more slowly, to choose the positive stimulus when it was paired with the ambiguous stimulus.

Response competition in monkeys' solution of PAN ambiguous-cue problems

Four monkeys were tested on a 2-choice object discrimination task involving 3 stimuli: P, positive and consistently rewarded; N, negative and consistently nonrewarded; and A, ambiguously rewarded depending upon whether paired with P on PA trials or N on NA trials. A preestablished prompt indicated the rewarded object (P on PA, A on NA trials) on initial training trials during which the ratio of PA to NA trials was 4/4, 4/8, or 4/12. All training trials were followed by 16 nonprompted test trials (8 PA and 8 NA). Performance on PA test trials decreased monotonically as a function of the preceding decreasing PA/NA ratios supporting the hypothesis of competition among independently acquired approach tendencies to P and A objects. This competition occurred even on training trials of 4/12 problems during which performance on PA trials was at chance despite the presence of the prompt. Corroborating and extending those of previous research, these results offer substantial additional support for the interfering-cue hypothesis.

An analysis of the solution of PAN ambiguous-cue problems by rhesus monkeys

Twenty-four monkeys were given 2-choice discrimination problems composed of three planometric plaque stimuli: P, the rewarded stimulus; N, the nonrewarded stimulus; and A, the ambiguous stimulus which was negative when paired with P, but positive when paired with N. When both pair of stimuli, PA and NA, were presented within a given session S was forced either to approach or to avoid the A plaque depending upon the stimulus with which it was paired. The results corroborated previous reports for plaque stimuli by showing PA performance to be superior to NA. The data also revealed that when plaque stimuli with distinctive cues were employed, NA performance exceeded PA as previously reported for stereometric object stimuli. Pretraining Ss with plaque stimuli possessing distinctive cues, then switching to plaques with less distinctive cues, also resulted in superior NA performance. These findings are discussed in the context of an interference-cue theory.

Learning after cerebral hemidecortication in monkeys

Abstract Cerebral hemidecorticated monkeys were given two ambiguous cue problems, a spatial stimulus-response discontiguity and a delayed-response problem. In comparison to the normal animals, the lesioned monkeys exhibited a deficit on the first ambiguous test and on the contiguity problem. There was not, as was predicted, a difference on the delayed-response test.

Ambiguous-cue problem performance of children, retardates, and monkeys.

Ambiguous-cue problem performance of children, retardates, and monkeys.

Monkeys' performance on ambiguous-cue problems.

9 experimentally naive rhesus monkeys were tested on ambiguous-cue problems involving three stimuli: P, the positive or rewarded stimulus; N, the negative or nonrewarded stimulus; and A, the ambiguous stimulus which is nonrewarded when paired with P, but rewarded when paired with N. Either the NA pair or the PA pair was presented on every trial. All Ss were tested with two types of stimuli, planometric plaques and stereometric objects. The results corroborate apparently conflicting previous reports of performance by primates on ambiguous-cue problems with these two types of stimuli. That is, performance on PA trials was superior to performance on NA trials with plaque stimuli, but the converse was obtained with objects. A differential S-R spatial discontiguity inherent in only the plaque version of the problem was identified as one cause of the discrepant results.

Monkeys' solution of an ambiguous-cue problem.

In a WGTA situation 12 monkeys were trained on a 2-choice discrimination task involving 3 stimuli: P, the consistently rewarded stimulus; N, the consistently nonrewarded stimulus; and A, the stimulus ambiguously rewarded depending upon whether it was paired with either P or N on a particular trial. Trials were either of the PA or NA type, and 6 Ss received a random schedule of such trials throughout 12 sessions while 6 Ss received a schedule designed to gradually introduce the two types of trials. The results unambiguously demonstrated that regardless of training method Ss were correct more often on the PA trial. Confirming and extending previous research, these data were interpreted in terms of parallel development of excitatory and inhibitory processes.

The Learning of Ambiguous Cue-Problems by Monkeys

The Learning of Ambiguous Cue-Problems by Monkeys