Asymmetries in cue competition in forward and backward blocking designs: Further evidence for causal model theory

A hallmark feature of elemental associative learning theories is that multiple cues compete for associative strength when presented with an outcome. Cue competition effects have been observed in humans, both in forward and in backward blocking procedures (e.g., Shanks, 1985) and are often interpreted as evidence for an associative account of human causal learning (e.g., Shanks & Dickinson, 1987). Waldmann and Holyoak (1992), however, demonstrated that cue competition only occurs in predictive, and not diagnostic, learning paradigms. While unexplainable from an associative perspective, this asymmetry readily follows from structural considerations of causal model theory. In this paper, we show that causal models determine the extent of cue competition not only in forward but also in backward blocking designs. Implications for associative and inferential accounts of causal learning are discussed.     

Predictive versus diagnostic causal learning: Evidence from an overshadowing paradigm

Causal directionality belongs to one of the most fundamental aspects of causality that cannot be reduced to mere covariation. This paper is part of a debate between proponents of associative theories, which claim that learners are insensitive to the causal status of cues and outcomes, and proponents of causal-model theory, which postulates an interaction of assumptions about causal directionality and learning. Some researchers endorsing the associationist view have argued that evidence for the interaction between cue competition and causal directionality may be restricted to two-phase blocking designs. Furthermore, from the viewpoint of causal-model theory, blocking designs carry the potential problem that the predicted asymmetries of cue competition are partly dependent on asymmetries of retrospective inferences. The present experiments use a one-phase overshadowing paradigm that does not allow for retrospective inferences and therefore represents a more unambiguous test of sensitivity to causal directionality. The results strengthen causal-model theory by clearly demonstrating the influence of causal directionality on learning. However, they also provide evidence for boundary conditions for this effect by highlighting the role of the semantics of the learning task.     

Mechanisms of predictive and diagnostic causal induction

In predictive causal inference, people reason from causes to effects, whereas in diagnostic inference, they reason from effects to causes. Independently of the causal structure of the events, the temporal structure of the information provided to a reasoner may vary (e.g., multiple events followed by a single event vs. a single event followed by multiple events). The authors report 5 experiments in which causal structure and temporal information were varied independently. Inferences were influenced by temporal structure but not by causal structure. The results are relevant to the evaluation of 2 current accounts of causal induction, the Rescorla-Wagner (R. A. Rescorla & A. R. Wagner, 1972) and causal model theories (M. R. Waldmann & K. J. Holyoak, 1992).     

Causal Learning: Association Versus Computation

Causal learning enables humans and other animals not only to predict important events or outcomes, but also to control their occurrence in the service of needs and desires. Computational theories assume that causal judgments are based on an estimate of the contingency between a causal cue and an outcome. However, human causal learning exhibits many of the characteristics of the associative learning processes thought to underlie animal conditioning. One problem for associative theory arises from the finding that judgments of the causal power of a cue can be revalued retrospectively after learning episodes when that cue is not present. However, if retrieved representations of cues can support learning, retrospective revaluation is anticipated by modified versions of standard associative theories.     

Competition among causes but not effects in predictive and diagnostic learning

Causal asymmetry is one of the most fundamental features of the physical world: Causes produce effects, but not vice versa. This article is part of a debate between the view that, in principle, people are sensitive to causal directionality during learning (causal-model theory) and the view that learning primarily involves acquiring associations between cues and outcomes irrespective of their causal role (associative theories). Four experiments are presented that use asymmetries of cue competition to discriminate between these views. These experiments show that, contrary to associative accounts, cue competition interacts with causal status and that people are capable of differentiating between predictive and diagnostic inferences. Additional implications of causal-model theory are elaborated and empirically tested against alternative accounts. The results uniformly favor causal-model theory.     

A Bayesian Theory of Sequential Causal Learning and Abstract Transfer

Two key research issues in the field of causal learning are how people acquire causal knowledge when observing data that are presented sequentially, and the level of abstraction at which learning takes place. Does sequential causal learning solely involve the acquisition of specific cause‐effect links, or do learners also acquire knowledge about abstract causal constraints? Recent empirical studies have revealed that experience with one set of causal cues can dramatically alter subsequent learning and performance with entirely different cues, suggesting that learning involves abstract transfer, and such transfer effects involve sequential presentation of distinct sets of causal cues. It has been demonstrated that pre‐training (or even post‐training) can modulate classic causal learning phenomena such as forward and backward blocking. To account for these effects, we propose a Bayesian theory of sequential causal learning. The theory assumes that humans are able to consider and use several alternative causal generative models, each instantiating a different causal integration rule. Model selection is used to decide which integration rule to use in a given learning environment in order to infer causal knowledge from sequential data. Detailed computer simulations demonstrate that humans rely on the abstract characteristics of outcome variables (e.g., binary vs. continuous) to select a causal integration rule, which in turn alters causal learning in a variety of blocking and overshadowing paradigms. When the nature of the outcome variable is ambiguous, humans select the model that yields the best fit with the recent environment, and then apply it to subsequent learning tasks. Based on sequential patterns of cue‐outcome co‐occurrence, the theory can account for a range of phenomena in sequential causal learning, including various blocking effects, primacy effects in some experimental conditions, and apparently abstract transfer of causal knowledge.     

Predictive and diagnostic learning within causal models: asymmetries in cue competition.

Several researchers have recently claimed that higher order types of learning, such as categorization and causal induction, can be reduced to lower order associative learning. These claims are based in part on reports of cue competition in higher order learning, apparently analogous to blocking in classical conditioning. Three experiments are reported in which subjects had to learn to respond on the basis of cues that were defined either as possible causes of a common effect (predictive learning) or as possible effects of a common cause (diagnostic learning). The results indicate that diagnostic and predictive reasoning, far from being identical as predicted by associationistic models, are not even symmetrical. Although cue competition occurs among multiple possible causes during predictive learning, multiple possible effects need not compete during diagnostic learning. The results favor a causal-model theory.     

返回抑制时程的三因素理论及其发展

综述了返回抑制(Inhibition of return,IOR)出现时程机制的三因素理论内容,支持该理论的实验证据,以及对理论的质疑和发展。该理论认为空间定向收益、出现检测缺失和空间选择收益三个因素共同决定了IOR出现的时程及机制。研究者通过操控任务加工水平或将实验范式相结合的方式对三因素理论提出了质疑和发展。许多关键问题如三个因素存在的认知神经科学证据、出现检测缺失和空间选择收益发挥作用的方式等是未来研究的重点和方向。     

The special status of actions in causal reasoning in rats

A. P. Blaisdell, K. Sawa, K. J. Leising, and M. R. Waldmann (2006) reported evidence for causal reasoning in rats. After learning through Pavlovian observation that Event A (a light) was a common cause of Events X (an auditory stimulus) and F (food), rats predicted F in the test phase when they observed Event X as a cue but not when they generated X by a lever press. Whereas associative accounts predict associations between X and F regardless of whether X is observed or generated by an action, causal-model theory predicts that the intervention at test should lead to discounting of A, the regular cause of X. The authors report further tests of causal-model theory. One key prediction is that full discounting should be observed only when the alternative cause is viewed as deterministic and independent of other events, 2 hallmark features of actions but not necessarily of arbitrary events. Consequently, the authors observed discounting with only interventions but not other observable events (Experiments 1 and 2). Moreover, rats were capable of flexibly switching between observational and interventional predictions (Experiment 3). Finally, discounting occurred on the very first test trial (Meta-Analysis). These results confirm causal-model theory but refute associative accounts.     

The 28th Bartlett Memorial Lecture Causal learning: An associative analysis

The concordance between performance and judgements of the causal effectiveness of an instrumental action suggests that such actions are mediated by causal knowledge. Although causal learning exhibits many associative phenomena—blocking, inhibitory or preventative learning, and super-learning—judgements of the causal status of a cue can be changed retrospectively as a result of learning episodes that do not directly involve the cue. In order to explain retrospective revaluation, a modified associative theory is described in which the learning processes for retrieved cue representations are the opposite to those for presented cues, and this theory is evaluated by studies of the role of within-compound associations in retrospective revaluation and blocking. However, this modified theory only applies when the within-compound association represents a contiguous rather than a causal cue relationship.     

Within-compound associations in retrospective revaluation and in direct learning: A challenge for comparator theory

In three human causal learning experiments we investigated the role of within-compound associations in learning about absent cues versus learning about present cues. Different theoretical approaches agree that within-compound associations are essential for learning about absent cues-that is, for retrospective revaluation. They differ, however, with regard to the role of within-compound associations for learning about present cues-that is, for direct learning. A memory test was used to assess within-compound associations. Experiment 1 used a blocking/release from overshadowing design, Experiment 2 used a conditioned inhibition design, and Experiment 3 used a higher-order cue selection design. In all experiments, first-order retrospective revaluation was significantly correlated with within-compound associations, but no significant correlations were found for the direct learning conditions. In addition to this, second-order retrospective revaluation in Experiment 3 was positively correlated to joint knowledge of first-order and second-order within-compound associations. Furthermore, cue selection effects were stronger for direct learning conditions than for retrospective learning conditions. These results are at variance with the comparator hypothesis but are in agreement with a modified associative theory and with the suggestion that retrospective revaluation might be due to rehearsal processes.     

Forward blocking in human learning sometimes reflects the failure to encode a cue–outcome relationship

In two “allergist” causal judgement experiments, participants were trained with a blocking design (A?+?|AB+). The procedure allowed different food cues to be paired with different fictitious allergic reactions. On test, participants were asked to rate the causal efficacy of the target cues and to recall the particular allergic reaction (outcome) that had followed each cue during training. Forward blocking was observed on the causal judgement measure and on the outcome recall measure in both Experiment 1 and Experiment 2. A backward blocking contingency was also trained in Experiment 2 (AB?+?|A+). Backward blocking was not observed either on the causal judgement or on the outcome recall measure. The evidence from the recall measure suggests that forward blocking in this task results from a failure to encode the B–outcome relationship during training. Associative and nonassociative mechanisms of forward blocking are discussed.     

Cue interaction effects in causal judgement: An interpretation in terms of the evidential evaluation model

In judging the extent to which a cue causes an outcome, judgement can be affected by information about other cues that are correlated with the one being judged. These cue interaction effects have usually been interpreted in terms of associative learning processes. I propose that a different model of causal judgement, the evidential evaluation model, offers a viable alternative interpretation of cue interaction phenomena. Under the evidential evaluation model, instances of contingency information are interpreted as evidence, which is confirmatory, disconfirmatory, or irrelevant for the cue being judged. When two cues co-occur in a set of instances the evidential value of the instances for one of them is determined by three factors: the proportion of confirming instances in the set; disambiguation value, which concerns the relation between the set of information and prior beliefs about the co-occurring cue; and confirmation value, which concerns the relation between the set of information and prior beliefs about the cue being judged. Any previous judgement of the cue is then modified in the light of these. It is shown that this model can account for all the cue interaction phenomena that have been investigated in studies of human causal judgement. The model also generates novel predictions, and the results of three experiments give support to these predictions. It is also shown that several other current models of causal judgement fail to predict a key result from Experiment 3.     

成人言语输入对儿童早期单词获得影响的个案追踪

追踪观察一名婴儿(6~20个月), 分析其中看护者的言语输入特征及婴儿早期词汇获得的发展变化。主要对成人言语输入中动、名词比例、单词在句中的位置、具体环境等因素及婴儿早期动、名词理解和产生等方面进行探讨。结果显示, 成人言语输入中动词比例显著高于名词, 更多动词位于句首或句尾使得主语和宾语省略; 同时, 这种动词优势的输入特征促进儿童早期动词获得, 使得婴儿早期语言样本中动、名词理解相对比例与成人言语输入一致。这一结果表明, 婴儿词汇发展初期就已经利用言语或社会线索, 同时这种早期词汇组成中较高的动词比例进一步支持“名词优势”理论存在跨语言差异     

Rethinking temporal contiguity and the judgement of causality: effects of prior knowledge, experience, and reinforcement procedure.

Time plays a pivotal role in causal inference. Nonetheless most contemporary theories of causal induction do not address the implications of temporal contiguity and delay, with the exception of associative learning theory. Shanks, Pearson, and Dickinson (1989) and several replications (Reed, 1992, 1999) have demonstrated that people fail to identify causal relations if cause and effect are separated by more than two seconds. In line with an associationist perspective, these findings have been interpreted to indicate that temporal lags universally impair causal induction. This interpretation clashes with the richness of everyday causal cognition where people apparently can reason about causal relations involving considerable delays. We look at the implications of cause-effect delays from a computational perspective and predict that delays should generally hinder reasoning performance, but that this hindrance should be alleviated if reasoners have knowledge of the delay. Two experiments demonstrated that (1) the impact of delay on causal judgement depends on participants' expectations about the timeframe of the causal relation, and (2) the free-operant procedures used in previous studies are ill-suited to study the direct influences of delay on causal induction, because they confound delay with weaker evidence for the relation in question. Implications for contemporary causal learning theories are discussed.     

Contingency awareness,partial reinforcement effects,and curiosity motivation in children

Third- and fourth-grade children were given a two-choice discrimination learning task, designed to associate each of three syllables with a different reward schedule: 100% reward, 50% reward, and 0% reward. Subsequent to the conditioning phase, measures were made of the subject's awareness of the reward contingencies associated with the syllables, as well as the pleasantness and curiosity which these syllables had acquired during the conditioning. The results showed that a partially rewarded cue was evaluated as somewhat less “pleasant” than a continuously rewarded cue, but evoked more “curiosity” than either the continuous or nonrewarded cues. These effects emerged only for the contingency aware groups.     

Competition Between Outcomes

In both Pavlovian conditioning and human causal judgment, competition between cues is well known to occur when multiple cues are presented in compound and followed by an outcome. More questionable is the occurrence of competition between outcomes when a single cue is followed by multiple outcomes presented in compound. In the experiment reported here, we demonstrated blocking (a type of stimulus competition) between outcomes. When the cue predicted one outcome, its ability to predict a second outcome that was presented in compound with the first outcome was reduced. The procedure minimized the likelihood that the observed competition between outcomes arose from selective attention. The competition between outcomes that we observed is problematic for contemporary theories of learning.     

The illusion of control: Sequential dependencies underlie contingent attentional capture

The degree to which humans have top-down control over which information they process remains a central debate within the attention literature. Most of the evidence supporting the top-down control of visuospatial attention has come from cueing paradigms in which target stimuli are preceded by cues that are similar or dissimilar from the target. These studies find that the cues similar to targets capture attention, but dissimilar cues do not, suggesting the top-down control of attention. Here, we used a modified cueing paradigm to investigate an alternative possibility that the cue type differences are due to sequential dependency effects occurring between cue and target processing rather than the top-down control of attention. When individuals searched for color targets, we replicated contingent capture effects in RTs, which are susceptible to sequential dependencies, but memory performance was always best at the cued locations, regardless of the cue’s identity. When individuals searched for onset targets, we observed contingent capture in both tasks. These results demonstrate the utility of the memory probe paradigm and suggest an asymmetry between how strongly onsets and color defined cues capture attention.     

Iconic memory: A reply to Professor Holding

Professor Holding has argued that the partial report superiority normally taken as evidence for the existence of iconic memory might instead be due to cue anticipation or output interference. I have suggested that both of these alternative explanations are inconsistent with the finding that the partial report superiority diminishes rapidly with increasing cue delay. In addition, Sperling’s original partial report experiment was designed in such a way that cue anticipation could not have occurred; and both his results with selection by letter vs number and Averbach and Coriell’s bar-marker results indicate that output interference effects are absent or negligible in tachistoscopic experiments. Consequently, I have concluded that the partial report superiority, and especially its decline with increasing delay, remains as strong evidence in favor of the conventional view of iconic memory. Furthermore, if this view were wrong, there would remain no way of giving a satisfactory account of (a) Averbach and Coriell’s results, (b) “direct” investigations of visual persistence, or (c) integration and interruption effects in backward visual masking.