Causal Networks or Causal Islands? The Representation of Mechanisms and the Transitivity of Causal Judgment

Knowledge of mechanisms is critical for causal reasoning. We contrasted two possible organizations of causal knowledge—an interconnected causal network, where events are causally connected without any boundaries delineating discrete mechanisms; or a set of disparate mechanisms—causal islands—such that events in different mechanisms are not thought to be related even when they belong to the same causal chain. To distinguish these possibilities, we tested whether people make transitive judgments about causal chains by inferring, given A causes B and B causes C, that A causes C. Specifically, causal chains schematized as one chunk or mechanism in semantic memory (e.g., exercising, becoming thirsty, drinking water) led to transitive causal judgments. On the other hand, chains schematized as multiple chunks (e.g., having sex, becoming pregnant, becoming nauseous) led to intransitive judgments despite strong intermediate links ((Experiments 1–3). Normative accounts of causal intransitivity could not explain these intransitive judgments (Experiments 4 and 5).     

Identifying expectations about the strength of causal relationships

When we try to identify causal relationships, how strong do we expect that relationship to be? Bayesian models of causal induction rely on assumptions regarding people’s a priori beliefs about causal systems, with recent research focusing on people’s expectations about the strength of causes. These expectations are expressed in terms of prior probability distributions. While proposals about the form of such prior distributions have been made previously, many different distributions are possible, making it difficult to test such proposals exhaustively. In Experiment 1 we used iterated learning—a method in which participants make inferences about data generated based on their own responses in previous trials—to estimate participants’ prior beliefs about the strengths of causes. This method produced estimated prior distributions that were quite different from those previously proposed in the literature. Experiment 2 collected a large set of human judgments on the strength of causal relationships to be used as a benchmark for evaluating different models, using stimuli that cover a wider and more systematic set of contingencies than previous research. Using these judgments, we evaluated the predictions of various Bayesian models. The Bayesian model with priors estimated via iterated learning compared favorably against the others. Experiment 3 estimated participants’ prior beliefs concerning different causal systems, revealing key similarities in their expectations across diverse scenarios.     

How great apes perform on a modified trap-tube task

To date, neither primates nor birds have shown clear evidence of causal knowledge when attempting to solve the trap tube task. One factor that may have contributed to mask the knowledge that subjects may have about the task is that subjects were only allowed to push the reward away from them, which is a particularly difficult action for primates in certain problem solving situations. We presented five orangutans (Pongo pygmaeus), two chimpanzees (Pan troglodytes), two bonobos (Pan paniscus), and one gorilla (Gorilla gorilla) with a modified trap tube that allowed subjects to push or rake the reward with the tool. In two additional follow-up tests, we inverted the tube 180° rendering the trap nonfunctional and also presented subjects with the original task in which they were required to push the reward out of the tube. Results showed that all but one of the subjects preferred to rake the reward. Two orangutans and one chimpanzee (all of whom preferred to rake the reward), consistently avoided the trap only when it was functional but failed the original task. These findings suggest that some great apes may have some causal knowledge about the trap-tube task. Their success, however, depended on whether they were allowed to choose certain tool-using actions. Electronic Supplementary Material Supplementary material is available for this article at     

Responses to symptom induction exercises in panic disorder

Exposure to panic symptoms (interoceptive exposure) is often included as part of treatment for panic disorder (PD), although little is known about the relative effects of particular symptom induction exercises. This study describes responses of individuals with PD and nonclinical controls to 13 standard symptom induction exercises and 3 control exercises. Generally, individuals with PD responded more strongly to symptom induction exercises than did controls. The exercises producing the most fear included spinning, hyperventilation, breathing through a straw, and using a tongue depressor. This study also reports findings regarding specific symptoms triggered by each exercise, the percentage of participants reporting fear during each exercise, and predictors of fear.     

Functional explanation and the function of explanation

Teleological explanations (TEs) account for the existence or properties of an entity in terms of a function: we have hearts because they pump blood, and telephones for communication. While many teleological explanations seem appropriate, others are clearly not warranted--for example, that rain exists for plants to grow. Five experiments explore the theoretical commitments that underlie teleological explanations. With the analysis of [Wright, L. (1976). Teleological Explanations. Berkeley, CA: University of California Press] from philosophy as a point of departure, we examine in Experiment 1 whether teleological explanations are interpreted causally, and confirm that TEs are only accepted when the function invoked in the explanation played a causal role in bringing about what is being explained. However, we also find that playing a causal role is not sufficient for all participants to accept TEs. Experiment 2 shows that this is not because participants fail to appreciate the causal structure of the scenarios used as stimuli. In Experiments 3-5 we show that the additional requirement for TE acceptance is that the process by which the function played a causal role must be general in the sense of conforming to a predictable pattern. These findings motivate a proposal, Explanation for Export, which suggests that a psychological function of explanation is to highlight information likely to subserve future prediction and intervention. We relate our proposal to normative accounts of explanation from philosophy of science, as well as to claims from psychology and artificial intelligence.     

Experiences of activity and causality in schizophrenia: When predictive deficits lead to a retrospective over-binding

In this paper I discuss an intriguing and relatively little studied symptomatic expression of schizophrenia known as experiences of activity in which patients form the delusion that they can control some external events by the sole means of their mind. I argue that experiences of activity result from patients being prone to aberrantly infer causal relations between unrelated events in a retrospective way owing to widespread predictive deficits. Moreover, I suggest that such deficits may, in addition, lead to an aberrant intentional binding effect i.e., the subjective compression of the temporal interval between an intentional action and its external effects (Haggard et al., 2002a, Haggard et al., 2002b). In particular, it might be that patient’s thoughts are bound to the external events they aimed to control producing, arguably, a temporal contiguity between these two components. Such temporal contiguity would reinforce or sustain the (causal) feeling that the patient mind is directly causally efficient.     

Developmental Study of the Reversed Stroop Effect in Chinese-English Bilinguals

Chinese-English bilinguals in Grades 2, 4, 8, 10, and in college read Chinese and English color words in black or in colored print in the corresponding language. Subjects were more efficient in reading Chinese than English. This superiority effect of reading Chinese gradually decreased as subjects' familiarity with English increased. Furthermore, skilled readers were less susceptible than less skilled readers to the introduction of conflicting colors of ink. This result indicates that the pattern of the reversed Stroop (1935; Dunbar & MacLeod, 1984) effect is related to the proficiency of word processing.     

N400 and P600 or the Role of the ERP Correlates in Sentence Comprehension: Some Applications to the Italian Language

In the present study, event-related brain potentials (ERPs) were applied to the study of language comprehension in the Italian language. The ERPs were recorded from 10 electrodes while the participants read (Experiment 1) or listened (Experiment 2) to sentences containing semantic or syntactic anomalies. Final words that were inconsistent with the sentence context elicited a negative wave at about 400 ms poststimulus that was more concentrated in the posterior sites of the scalp, whereas final words that were incongruous with the grammatical structure (subject-verb nonagreement) elicited a positive wave at about 600 ms poststimulus that was homogeneously distributed on the scalp. The authors found no differences based on the perceptual modality of the stimulus (visual or auditory), nor did they find different ERP correlates as a function of task relevance (explicit-implicit task induction). The available evidence indicated that the ERP response to semantic anomalies was at least partially distinct from the ERP response to syntactic anomalies, and that a syntactic parser is a plausible process included in sentence comprehension. The two semantic and syntactic effects appear as automatic processes of the decoding of the anomalies and also modality-independent processes. Cross-linguistic applications are considered in the general discussion.     

Arrogant or self-confident? The use of contextual knowledge to differentiate hubristic and authentic pride from a single nonverbal expression

Two studies tested whether observers could differentiate between two facets of pride—authentic and hubristic—on the basis of a single prototypical pride nonverbal expression combined with relevant contextual information. In Study 1, participants viewed targets displaying posed pride expressions in response to success, while causal attributions for the success (target's effort vs. ability) and the source of this information (target vs. omniscient narrator conveying objective fact) were varied. Study 2 used a similar method, but attribution information came from both the target and an omniscient narrator; the congruence of these attributions was varied. Across studies, participants tended to label expressions as authentic pride, but were relatively more likely to label them as hubristic pride when (a) contextual information indicated that targets were arrogant and (b) no mitigating information about the target's potential value as a hard-working group member (i.e., that success was actually due to effort) was presented.