Cue discovery in probabilistic environments: Uncertainty and experimentation.

It is argued that cue discovery is an important part of the task of learning from experience in probabilistic environments. Cue discovery involves the identification of new valid predictive cues, and their incorporation into the learner's mental model. In contrast, previous work in "multiple-cue probability learning" has focused principally on learning the quantitative characteristics of given cue–criterion relations. In two studies presented here, 36 college students learned to predict the behavior of a computer-controlled graphic display. The criterion behavior was a function of four to six cues, including several not explicitly identified. Analyses of test results, verbal reports, and behavior during learning indicate that subjects used outcome feedback to accomplish cue discovery. This process was accomplished more effectively when subjects were permitted to experiment by designing their own learning experiences. A distinction is drawn between a system whose behavior is unpredictable because of the presence of unknown controlling variables, and one that contains "random" error. Cue discovery may be more difficult in the latter case, but is accomplished nonetheless. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Storage and retrieval of associative clusters: A stages-of-learning analysis of associative memory traces.

In this research, the assumptions underlying the unitary trace theory of item representation and acquisition were tested in two cued-recall experiments in which the degree of preexperimental knowledge (typicality) was manipulated. Subjects learned lists of word triads (each of which consisted of a single cue and two targets) to a stringent acquisition criterion. In Experiment 1, typicality was manipulated in the absence of semantic relationships between members of the associative clusters. In Experiment 2, semantic relationships were present among cluster members, and preexperimental knowledge was manipulated by varying the degree of intracluster category membership as measured by whether cue and target items were typical or atypical category exemplars. In both experiments a mathematical model that embodies stages-of-learning distinctions was used to analyze the acquisition data. The results indicated that (1) cues and targets were represented in a single holistic memory trace, and (2) the manipulation of the degree of preexperimental knowledge affected both trace storage and retrieval learning, but had only a minimal impact on retrieval performance between the time a trace was stored and the time retrieval learning was complete. It was argued that these findings are consistent with a single unitary trace interpretation, namely, the modified storage-retrieval model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation of place and cue learning by telencephalic ablation in goldfish.

This study examined the spatial strategies used by goldfish (Carassius auratus) to find a goal in a 4-arm maze and the involvement of the telencephalon in this spatial learning. Intact and telencephalon-ablated goldfish were trained to find food in an arm placed in a constant room location and signaled by a local visual cue (mixed place-cue procedure). Both groups learned the task, but they used different learning strategies. Telencephalon-ablated goldfish learned the task more quickly and made fewer errors to criterion than controls. Probe trials revealed that intact goldfish could use either a place or a cue strategy, whereas telencephalon-ablated goldfish learned only a cue strategy. The results offer additional evidence that place and cue learning in fish are subserved by different neural substrates and that the telencephalon of the teleost fish, or some unspecified structure within it, is important for spatial learning and memory in a manner similar to the hippocampus of mammals and birds. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociation Between Judgments and Outcome-Expectancy Measures in Covariation Learning: A Signal Detection Theory Approach.

A number of studies using trial-by-trial learning tasks have shown that judgments of covariation between a cue c and an outcome o deviate from normative metrics. Parameters based on trial-by-trial predictions were estimated from signal detection theory (SDT) in a standard causal learning task. Results showed that manipulations of P(c) when contingency (ΔP) was held constant did not affect participants' ability to predict the appearance of the outcome (d') but had a significant effect on response criterion (c) and numerical causal judgments. The association between criterion c and judgment was further demonstrated in 2 experiments in which the criterion was directly manipulated by linking payoffs to the predictive responses made by learners. In all cases, the more liberal the criterion c was, the higher judgments were. The results imply that the mechanisms underlying the elaboration of judgments and those involved in the elaboration of predictive responses are partially dissociable. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Acquisition of discrimination learning of patterns identical in configuration in macaques (Macaca mulatta and M. fuscata).

Compared the acquisition of discrimination of 5 pairs of pattern cues in a Wisconsin General Testing Apparatus by 223 naive macaque monkeys. The pairs of discriminanda were identical in configuration but varied slightly in either the size of the cue or the size of the background plaque; thus, the degree of separation of the cue from the fringe of the plaque, the response site, was slightly different for each pair of discriminanda. These small differences in cue–response separation had marked effects on the rate of acquisition of the discriminations. Even an increment of separation as small as 0.5 cm resulted in a retardation of the acquisition. This retardation was due to prolonged performance at the chance level and not to a slow rate of improvement from the chance to a criterion level. The finding indicates that the difficulty in the acquisition learning on pattern tasks depends largely on the difficulty of attending to the pattern cues at small cue–response separations. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning in a changing environment.

Multiple cue probability learning studies have typically focused on stationary environments. We present 3 experiments investigating learning in changing environments. A fine-grained analysis of the learning dynamics shows that participants were responsive to both abrupt and gradual changes in cue–outcome relations. We found no evidence that participants adapted to these types of change in qualitatively different ways. Also, in contrast to earlier claims that these tasks are learned implicitly, participants showed good insight into what they learned. By fitting formal learning models, we investigated whether participants learned global functional relationships or made localized predictions from similar experienced exemplars. Both a local (the associative learning model) and a global learning model (the Bayesian linear filter) fitted the data of the first 2 experiments. However, the results of Experiment 3, which was specifically designed to discriminate between local and global learning models, provided more support for global learning models. Finally, we present a novel model to account for the cue competition effects found in previous research and displayed by some of our participants. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Inescapable shock and attention to internal versus external cues in a water discrimination escape task.

In these experiments we examined discrimination learning in a water escape task following exposure to escapable, yoked inescapable, or no electric shock. Inescapable shock did not have an effect on swim speeds in any of the experiments. Inescapable shock interfered with the acquisition of a position (left–right) discrimination when an irrelevant brightness cue (black and white stimuli) was present. However, inescapable shock did not affect the acquisition of the position discrimination when the irrelevant brightness cue was removed. Inescapably shocked Subjects showed facilitated learning relative to escapably shocked and nonshocked subjects when the brightness cue was included as a relevant cue. These data may resolve discrepancies between studies that did, and did not, find inescapable shock to interfere with the acquisition of discriminations. Moreover, they point to attentional processes as one locus of the cognitive changes produced by inescapable shock and suggest the exposure to inescapable shock biases attention away from "internal" response-related cues toward "external" cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A developmental study of hypothesis testing and cue selection strategies.

Previous investigators who have evaluated M. Levine's hypothesis testing model of learning have employed blank-trial probes in order to determine which hypothesis was sampled on specific trials. A method of determining which hypothesis was sampled that did not require blank trials was administered to children in Grades 1, 3, and 5, undergraduates, and old adults (mean age = 75 years). A 2-choice, multidimensional discrimination task was presented in which the Ss first chose the stimulus thought to be correct and then pointed to a single cue in a complete set of decomposed cues from the learning task. Results are in accord with other studies of hypothesis testing in that developmental differences were observed. Younger and older children differed in the cue selection strategies used during learning. Undergraduates used very efficient strategies that often led to learning, while the old adults were quite inconsistent and often failed to recognize when they had selected the correct reinforced cue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester on spatial and cued leaning

An investigation was made of the effects of the nitric oxide synthase inhibitor NG-nitro-L-arginine methyl ester (L-NAME) on the acquisition and retention of two operantly conditioned discrimination tasks. Twenty Long-Evans rats were conditioned to approach one of two spatial locations that was either held constant across trials (spatial task) or was associated with a visual cue (illuminated lamp) that was randomly assigned to one of the locations on each trial (cued task). Rats were assigned to one of two treatment groups in which they received intraperitoneal injections of either NG-nitro-L-arginine methyl ester or saline approximately 2 h before sessions on each day of training. Analysis was made of the trial-by-trial performance in order to identify the characteristics of learning under each condition. Assessment of learning acquisition was based on the number of trials required to reach a criterion of 80% correct responses, whereas retention was assessed by the number of trials to criterion on each day after the criterion was initially reached. Analysis indicated that treatment groups did not differ significantly on acquisition or retention of either the spatial or cued task. These results indicate that inhibition of nitric oxide synthase does not interfere with the learning or retention of basic operant tasks that involve simple spatial or visual analysis. Whereas results from biochemical and physiological investigations have suggested an impact of nitric oxide synthase on behavioural function, behavioural investigations indicate a limited impact of nitric oxide synthase inhibition on learning and memory. Although these results do not discount the role of nitric oxide synthase in a hippocampal mechanism, they illustrate that behavioural analysis should be made in the context of multiple interacting neural systems. Viewed with previous behavioural research on the effects of NG-nitro-L-arginine methyl ester, these results indicate that nitric oxide synthase inhibition results in impairment of certain forms of learning whereas other forms are preserved.     

The influence of blocking on overt attention and associability in human learning.

Previous studies have demonstrated a retardation in the rate of novel learning about previously blocked cues as compared to appropriate control cues. We report an experiment investigating whether this retardation in novel learning about a blocked cue is accompanied by a reduction in attention to this cue, as anticipated by attentional theories of associative learning. Consistent with these theories, eye gaze measures revealed a reduction in overt attention to the blocked cue both during the compound training phase of the blocking procedure, and also during novel learning with respect to new outcomes. Moreover, the extent of the bias in overt attention away from blocked cues was positively correlated with the subsequent reduction in rate of novel learning about these cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Dissociations between expectancy and performance in simple and two-choice reaction-time tasks: A test of associative and nonassociative explanations.

Perruchet, Cleeremans, and Destrebecqz (2006) reported a striking dissociation between trends in the conscious expectancy of an event and the speed of a response that is cued by that event. They argued that this indicates the operation of independent processes in human associative learning. However, there remains a strong possibility that this dissociation is not a consequence of associative learning and is instead caused by changes in vigilance or sensitivity based on the recency of events on previous trials. Three experiments tested this possibility with versions of a cued reaction time task in which trends in performance could not be explained by these nonassociative factors. Experiment 1 introduced a dual-response version of the task, in which response-related vigilance should be held relatively constant, and Experiments 2 and 3 used a differential conditioning procedure to separate the influence of recent response cue presentation from the recent associative history of the trial events. In all experiments, similar trends in reaction time were evident, suggesting a genuine influence of associative learning on response performance. Experiment 3 demonstrated that the associative contribution to these trends was not caused by commensurate changes in expectancy of the response cue. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptual identification of contextual attributes and infant memory retrieval.

The contribution of specific contextual attributes to recognition of a well-learned cue was examined in 4 experiments with 6-mo-olds. 24 hrs after learning to move a given mobile in a distinctive visual surround by kicking, recognition of the training cue was tested in either the original context or in one in which only a single contextual attribute was altered. Retrieval was completely disrupted by all form changes involving the deletion of angles and by a chromatic figure/ground reversal, but a discriminable change in form color had no effect. Although infants displayed partial retention in a degraded context after 1 day, they displayed no retention when a reminder was administered in the same degraded context after 20 days. These data reveal that infants do not encode contextual information holistically; moreover, they imply a privileged status for highly specific information about the incidental setting in which an event occurs. Unless this same highly specific information is perceptually identified at the time of testing, the memory of that event will not be retrieved. Data are consistent with the hypothesis that the visual context serves as an initial attention gate for memory retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Observation and discrimination learning in the rat: Specific and nonspecific effects.

After watching the performance of a model rat (N = 10), 48 Os (naive male hooded rats) were trained on a visual pattern discrimination. Results show that the observational experience facilitated discrimination learning if the same cue pattern was positive for the model and the O; it retarded learning in Ss trained on the reversal of the observed discrimination. These results depend on the viewing of a model contiguous with the cue pattern. A 2nd type of facilitating effect followed visual exposure to the cue patterns presented without a model S. When such an observational condition involved stimulus change, discrimination learning was facilitated regardless of the cue to be approached. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Choice strategies in multiple-cue probability learning.

Choice strategies for selecting among outcomes in multiple-cue probability learning were investigated using a simulated medical diagnosis task. Expected choice probabilities (the proportion of times each outcome was selected given each cue pattern) under alternative choice strategies were constructed from corresponding observed judged probabilities (of each outcome given each cue pattern) and compared with observed choice probabilities. Most of the participants were inferred to have responded by using a deterministic strategy, in which the outcome with the higher judged probability is consistently chosen, rather than a probabilistic strategy, in which an outcome is chosen with a probability equal to its judged probability. Extended practice in the learning environment did not affect choice strategy selection, contrary to reports from previous studies, results of which may instead be attributable to changes with practice in the variability and extremity of the perceived probabilities on which the choices were based. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The hide-and-seek of retrospective revaluation: Recovery from blocking is context dependent in human causal learning.

In a typical blocking procedure, pairings of a compound consisting of 2 stimuli, A and X, with the outcome are preceded by pairings of only A with the outcome (i.e., A+ then AX+). This procedure is known to diminish responding to the target cue (X) relative to a control group that does not receive the preceding training with blocking cue A. We report 2 experiments that investigated the effect of extinguishing a blocking cue on responding to the target cue in a human causal learning paradigm (i.e., A+ and AX+ training followed by A– training). The results indicate that extinguishing a blocking cue increases conditioned responding to the target cue. Moreover, this increase appears to be context dependent, such that increased responding to the target is limited to the context in which extinction of the blocking cue took place. We discuss these findings in the light of associative and propositional learning theories. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Control of spatial orientation in terrestrial toads (Rhinella arenarum).

Three experiments were conducted to determine problem-solving strategies used by toads, Rhinella arenarum (= Bufo arenarum), in spatial learning situations, using water as reward. Experiment 1 showed that toads can acquire a spatial orientation based on a body-centered turn -an internal self-reference cue. Experiment 2 showed that toads can use a fixed landmark (visual cue) as guidance to solve a spatial problem. Experiment 3 determined whether maze learning was based on “body-centered turn” or “guidance”. In this case, animals were trained with a fixed visual cue in relation to a body-centered turn (i.e., simultaneously with the internal self-reference cue) and then tested with the visual cue dissociated from positional cues. Toads trained with the combination of a visual cue and a body-centered turn preferred the latter (turn response) when the two sources of information were set in conflict on probe trials. Toads showed behavioral patterns similar to those described in rodents trained under similar condition, thus, suggesting an early evolutionary origin for these problem-solving strategies. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The crucial role of postcue encoding in directed forgetting and context-dependent forgetting.

People can intentionally forget previously studied material if, after study, a forget cue is provided and new material is learned. It has recently been suggested that such list-method directed forgetting arises because the forget cue induces a change in internal context and causes context-dependent forgetting of the studied material (L. Sahakyan & C. M. Kelley, 2002). The authors compared directed forgetting and context-dependent forgetting by examining whether, like a forget cue, a change in internal context needs subsequent learning of new material to be effective. Participants studied an item list and, after study, received a remember cue or a forget cue or their internal context was changed through an imagination task. In each condition, half the participants learned a second list, and the other half fulfilled an unrelated distractor task. Both the forget cue and the change in internal context induced forgetting of the first list only when learning of the second list was interpolated. These results suggest that postcue encoding of new material is crucial for both directed forgetting and (some forms of) context-dependent forgetting. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hippocampal function in avoidance learning and punishment.

Discusses the effects of hippocampal lesions in avoidance and punishment situations. It is proposed that animals with such lesions cannot process information about places and therefore cannot employ place strategies in avoidance learning and punishment situations; they can only employ cue strategies that involve learning to approach or avoid a cue or to perform a response in the presence of a cue. Intact animals, on the other hand, can employ both place and cue strategies. The data are, to a large extent, consistent with this hypothesis. Implications for theories of learning in situations involving aversive reinforcers are discussed. (125 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of small cue–response separation on pattern discrimination in macaques (Macaca fuscata and M. mulatta).

Three studies with 17 macaque and 6 rhesus monkeys examined the effect of small cue–response separations on Ss' pattern discriminations. When training on a pattern discrimination with a cue–response separation was discontinued during performance at the chance level, there was no saving on the rate of learning a 2nd task (with identical cues but a different cue–response separation) relative to the performance of naive control Ss. By contrast, when training was discontinued at a performance level a little better than chance, there was significant saving on learning a 2nd task. After learning the 2nd task, a 3rd task with new pattern cues was learned, with marked saving on the duration of performance at the chance level. Results indicate that during the initial stage of performance at the chance level, monkeys do not attend to cues if there is even a small separation between the cue and the response site. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning of absolute and relative distance and direction from discrete visual landmarks by pigeons (Columba livia).

In an open-field search task, pigeons (Columba livia) were trained to search for a goal located at the midpoint of the hypothetical line connecting two discrete visual landmarks positioned 60 cm apart. In Experiment 1, global orienting cues were absent. After reaching training criteria, pigeons were tested with novel interlandmark distances. Search location and error on test trials suggested pigeons learned relative distance. In Experiment 2, a global orienting cue was present. After reaching training criteria, pigeons were again tested with novel interlandmark distances. Results suggested pigeons learned relative and absolute distances. In Experiment 3, pigeons searched at the midpoint of rotated arrays in both the presence and absence of an orienting cue indicating learning of relative direction. In Experiment 4, pigeons searched in the appropriate goal direction when presented with a single landmark in the presence of the orienting cue but not in its absence indicating learning of absolute direction. Results implicate a stable frame of reference as critical to spatial coding strategies and suggest pigeons are able to code location based on absolute and relative distance and direction from discrete visual landmarks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)