The meaning(s) of conditionals: Conditional probabilities, mental models, and personal utilities.

[Correction Notice: An erratum for this article was reported in Vol 29(6) of Journal of Experimental Psychology: Learning, Memory, and Cognition (see record 2007-16865-001). On page 684, Table 4, all correlations should have been identified as having a pp then q") as indicating a high conditional probability P(q|p). Participants estimated the probability that a given conditional is true (Experiments 1A, 1B, and 3) or judged whether a conditional was true or false (Experiments 2 and 4) given information about the frequencies of the relevant truth table cases. Judgments were strongly influenced by the ratio of pq to p?q cases, supporting the conditional probability account. In Experiments 1A, 1B, and 3, judgments were also affected by the frequency of pq cases, consistent with a version of mental model theory. Experiments 3 and 4 extended the results to thematic conditionals and showed that the pragmatic utility associated with believing a statement also affected the degree of belief in conditionals but not in logically equivalent quantified statements. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditionals and conditional probability.

The authors report 3 experiments in which participants were invited to judge the probability of statements of the form if p then q given frequency information about the cases pq, p?q, ?pq, and ?p?q (where ? = not). Three hypotheses were compared: (a) that people equate the probability with that of the material conditional, 1 - P(p?q); (b) that people assign the conditional probability, P(q/p); and (c) that people assign the conjunctive probability P(pq). The experimental evidence allowed rejection of the 1st hypothesis but provided some support for the 2nd and 3rd hypotheses. Individual difference analyses showed that half of the participants used conditional probability and that most of the remaining participants used conjunctive probability as the basis of their judgments. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The negated conditional: A litmus test for the suppositional conditional?

Under the suppositional account of conditionals, when people think about a conditional assertion, "if p then q," they engage in a mental simulation in which they imagine p holds and evaluate the probability that q holds under this supposition. One implication of this account is that belief in a conditional equates to conditional probability [P(q/p)]. In this paper, the authors examine a further implication of this analysis with respect to the wide-scope negation of conditional assertions, "it is not the case that if p then q." Under the suppositional account, nothing categorically follows from the negation of a conditional, other than a second conditional, "if p then not-q." In contrast, according to the mental model theory, a negated conditional is consistent only with the determinate state of affairs, p and not-q. In 4 experiments, the authors compare the contrasting predictions that arise from each of these accounts. The findings are consistent with the suppositional theory but are incongruent with the mental model theory of conditionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reasoning counterfactually: Making inferences about things that didn't happen.

The authors investigated the relationship between reasoners' understanding of subjunctive conditionals (e.g., if p had happened, then q would have happened) and the inferences they were prepared to endorse. Reasoners who made a counterfactual interpretation of subjunctive statements (i.e., they judged the statement to imply that p and q did not happen) endorsed different inferences than those who did not. Those who made a counterfactual interpretation were more likely to (a)judge the situation in which p and q occurred to be inconsistent with the conditional statement and (b) make negative inferences such as modus tollens (i.e., – q therefore – p ). These findings occurred with familiar and unfamiliar content, affirmative and negative conditionals, and conditional and biconditional relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Computational levels and conditional inference: Reply to Schroyens and Schaeken (2003).

This article is a reply to W. Schroyens and W. Schaeken's (2003; see record 2002-08431-014) critique of M. Oaksford, N. Chater, and J. Larkin's (2000; see record 2000-08540-005) conditional probability model (CP) of conditional inference. It is argued that their meta-analysis does not falsify CP because the evidence may bear on more than one computational level of explanation. Moreover, it is argued that CP provides a rational account of more of the data than W. Schroyens and W. Schaeken's mental models theory. Other points are also addressed. It is suggested that W. Schroyens and W. Schaeken's model and CP converge on the importance of probabilistic prior knowledge in conditional inference. This is consistent with the normative literature, which (like CP) treats conditionals in terms of subjective conditional probabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counterfactual and Semifactual Conditionals Prime Alternative Possibilities.

The authors examined in 3 experiments the comprehension of counterfactuals, such as "If it had rained, the plants would have bloomed," and semifactuals, such as "Even if it had rained, the plants would have bloomed," compared with indicative conditionals, "If it rained, the plants bloomed." The first experiment showed that people read the negative conjunction, "not p and not q" faster when it was primed by a counterfactual than when it was primed by an indicative conditional. They read the affirmative conjunction, "p and q" equally quickly when it was primed by either conditional. The 2nd experiment showed that people read the negated-antecedent conjunction, "not p and q" faster when it was primed by a semifactual conditional. The 3rd experiment corroborated these results in a direct comparison of counterfactuals and semifactuals. The authors discuss the implications of the results for the mental representations of different conditionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditions for the Acceptance of Deontic Conditionals.

Recent psychological research has investigated how people assess the probability of an indicative conditional. Most people give the conditional probability of q given p as the probability of if p then q. Asking about the probability of an indicative conditional, one is in effect asking about its acceptability. But on what basis are deontic conditionals judged to be acceptable or unacceptable? Using a decision theoretic analysis, we argue that a deontic conditional, of the form if p then must q or if p then may q, will be judged acceptable to the extent that the p & q possibility is preferred to the p & not-q possibility. Two experiments are reported in which this prediction was upheld. There was also evidence that the pragmatic suitability of permission rules is partly determined by evaluations of the not-p & q possibility. Implications of these results for theories of deontic reasoning are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditionals: A theory of meaning, pragmatics, and inference.

The authors outline a theory of conditionals of the form If A then C and If A then possibly C. The 2 sorts of conditional have separate core meanings that refer to sets of possibilities. Knowledge, pragmatics, and semantics can modulate these meanings. Modulation can add information about temporal and other relations between antecedent and consequent. It can also prevent the construction of possibilities to yield 10 distinct sets of possibilities to which conditionals can refer. The mental representation of a conditional normally makes explicit only the possibilities in which its antecedent is true, yielding other possibilities implicitly. Reasoners tend to focus on the explicit possibilities. The theory predicts the major phenomena of understanding and reasoning with conditionals. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Consequential Conditionals: Invited and Suppressed Inferences From Valued Outcomes.

Consequential conditionals are defined as "if P then Q" statements, where P is an action, and Q a predicted outcome of this action, which is either desirable or undesirable to the agent. Experiment 1 shows that desirable (viz. undesirable) outcomes invite an inference to the truth (viz. falsity) of their antecedent. Experiment 2 shows that the more extreme the outcome is, the stronger the invited inference is. Experiment 3 shows that modus ponens from premises "If A then C, A" can be suppressed with the introduction of a consequential conditional, "If C then Q," where Q is an undesirable outcome. Experiment 4 shows that the more undesirable Q is, the larger the suppression is. The authors discuss how these results can enrich current approaches of conditional inference on the basis of mental models, complementary necessary conditions, and conditional probabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditional reasoning in children.

Conditional reasoning ability is analyzed in the context of Piaget's logical operational system. It is argued that facility in concrete operations is necessary and sufficient for competence in the simple syllogistic forms, though dealing with conditional statements in certain more complex contexts requires formal operations. Data from 3 studies are presented in support of these assertions. Using a total of 120 Ss in Grades 1–5, results of Exps I and II show that presentation of statements in a concrete conversational context elicited substantially more correct conditional reasoning than has been found in earlier studies. Results of Exp III, which used a total of 154 Ss in Grades 2, 4, 6, and 8, indicate that a distinction is drawn between comprehension that p (not p) entails the possibility of q (given If p, then q) and comprehension that q entails the possibility of p. The former is less difficult than the latter, and only the latter requires concrete operations. A methodological implication of these studies is that in the assessment of logical competence, results depend heavily on the exact manner of presentation, as well as on the specific logical operation being assessed. Implications for the theory of formal operations and for the study of traditional syllogistic reasoning are also discussed. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Amphetamine sensitization: Nonassociative and associative components": Correction to Wang and Hsiao (2003).

Reports an error in "Amphetamine sensitization: Nonassociative and associative components" by Ying-Chou Wang and Sigmund Hsiao (Behavioral Neuroscience, 2003[Oct], Vol 117[5], 961-969). The institutional affiliation for Ying-Chou Wang is incomplete. The correct affiliation is Ching Kuo Institute of Management and Health and National Chung Cheng University. (The following abstract of the original article appeared in record 2003-08567-009.) Rats, pretreated with amphetamine (AMPH, 1 mg/kg) or saline for 2 weeks, were challenged with AMPH (0.5 mg/kg) or saline following 1 week of abstinence, and locomotion was measured. In Experiments 1 and 2, the pretreatment occurred in various contexts (home cage, novel box, test box). Sensitization was observed only when pretreatment context and test context were the same; a context switch abolished sensitization. When rats anesthetized with chloral hydrate were pretreated with AMPH, sensitization was completely dependent on the pretreatment, but independent of context. This "zero context" condition isolated the basal level of excitation attributable to unconditioned neural change to determine the role of contextual input to be a modulator that enhances or inhibits sensitization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Critical history of the acculturation psychology of assimilation, separation, integration, and marginalization": Correction to Rudmin (2003).

Reports an error in the original article by F. W. Rudmin (Review of General Psychology, 2003[Mar], Vol 7[1], pp. 3-37). Six errors in this article are described. Readers of the critical history are also directeced to the work of J. Berry (2003) in acculturation psychology. (The following abstract of this article originally appeared in record 2003-01663-002.) The psychology of intercultural adaptation was first discussed by Plato. Many modern enculturation theories claim that ethnic minorities (including aboriginal natives, immigrants, refugees, and sojourners) can favor either the dominant culture, or their own minority culture, or both, or neither. Between 1918 and 1984, 68 such theories showed varied and inconsistent terminology, poor citation of earlier research, conflicting and poorly tested predictions of acculturative stress, and lack of logic, for example, 2 cultures in contact logically allow 16 types of acculturation, not just 4. Logic explains why assimilation = negative chauvinism = marginality, why measures of incompatible acculturative attitudes can be positively correlated, and why bicultural integration and marginalisation are confounded constructs. There is no robust evidence that biculturalism is most adaptive. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

"Learning myopia: An adaptive recency effect in category learning": Correction to Jones and Sieck (2003).

Reports an error in "Learning myopia: An adaptive recency effect in category learning" by Matt Jones and Winston R. Sieck (Journal of Experimental Psychology: Learning, Memory, and Cognition, 2003[Jul], Vol 29[4], 626-640). On page 633, Table 2, the values in columns (T, P) and (P, T) in the dual condition row incorrectly read .10 and .90, respectively. The correct values are .90 and .10, respectively. (The following abstract of the original article appeared in record 2003-06626-013.) Recency effects (REs) have been well established in memory and probability learning paradigms but have received little attention in category learning research. Extant categorization models predict REs to be unaffected by learning, whereas a functional interpretation of REs, suggested by results in other domains, predicts that people are able to learn sequential dependencies and incorporate this information into their responses. These contrasting predictions were tested in 2 experiments involving a classification task in which outcome sequences were autocorrelated. Experiment 1 showed that reliance on recent outcomes adapts to the structure of the task, in contrast to models' predictions. Experiment 2 provided constraints on how sequential information is learned and suggested possible extensions to current models to account for this learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Analysis of genomic alterations in benign, atypical, and anaplastic meningiomas: toward a genetic model of meningioma progression

Nineteen benign [World Health Organization (WHO) grade I; MI], 21 atypical (WHO grade II; MII), and 19 anaplastic (WHO grade III; MIII) sporadic meningiomas were screened for chromosomal imbalances by comparative genomic hybridization (CGH). These data were supplemented by molecular genetic analyses of selected chromosomal regions and genes. With increasing malignancy grade, a marked accumulation of genomic aberrations was observed; i.e., the numbers (mean +/- SEM) of total alterations detected per tumor were 2.9 +/- 0.7 for MI, 9.2 +/- 1.2 for MII, and 13.3 +/- 1.9 for MIII. The most frequent alteration detected in MI was loss on 22q (58%). In MII, aberrations most commonly identified were losses on 1p (76%), 22q (71%), 14q (43%), 18q (43%), 10 (38%), and 6q (33%), as well as gains on 20q (48%), 12q (43%), 15q (43%), 1q (33%), 9q (33%), and 17q (33%). In MIII, most of these alterations were found at similar frequencies. However, an increase in losses on 6q (53%), 10 (68%), and 14q (63%) was observed. In addition, 32% of MIII demonstrated loss on 9p. Homozygous deletions in the CDKN2A gene at 9p21 were found in 4 of 16 MIII (25%). Highly amplified DNA sequences were mapped to 12q13-q15 by CGH in 1 MII. Southern blot analysis of this tumor revealed amplification of CDK4 and MDM2. By CGH, DNA sequences from 17q were found to be amplified in 1 MII and 8 MIII, involving 17q23 in all cases. Despite the high frequency of chromosomal aberrations in the MII and MIII investigated, none of these tumors showed mutations in exons 5-8 of the TP53 gene. On the basis of the most common aberrations identified in the various malignancy grades, a model for the genomic alterations associated with meningioma progression is proposed.     

On the probability of making Type I errors.

A statistical test leads to a Type I error whenever it leads to the rejection of a null hypothesis that is in fact true. The probability of making a Type I error can be characterized in the following 3 ways: the conditional prior probability, the overall prior probability, and the conditional posterior probability. In this article, we show (a) that the alpha level can be equated with the 1st of these and (b) that it provides an upper bound for the second but (c) that it does not provide an estimate of the third, although it is commonly assumed to do so. We trace the source of this erroneous assumption first to statistical texts used by psychologists, which are generally ambiguous about which of the 3 interpretations is intended at any point in their discussions of Type I errors and which typically confound the conditional prior and posterior probabilities. Underlying this, however, is a more general fallacy in reasoning about probabilities, and we suggest that this may be the result of erroneous inferences about probabilistic conditional statements. Finally, we consider the possibility of estimating the (posterior) probability of a Type I error in situations in which the null hypothesis is rejected and, hence, the proportion of statistically significant results that may be Type I errors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditional reasoning, causality, and the structure of semantic memory: strength of association as a predictive factor for content effects

Available evidence indicates that responses to conditional inferences using concrete causal premises is affected by the relative number of available alternate causes (Cummins, D.D., 1995. Memory and Cognition 23 (5), 646-658). We propose that another important factor that may influence the kinds of inferences made to causal conditionals is the relative strength of association between such causes and the consequent term. We present a study with adult participants that examines the effect of strength of association on performance on a conditional reasoning task using causal premises for which there exist one highly associated potential cause for the given consequent term. We predicted that adults would produce a greater proportion of biconditional responses to invalid forms with strongly associated premises than weakly associated ones, while valid forms would not be affected by strength of association. The results are consistent with this hypothesis.     

Hematologic malignancies with t(4;11)(q21;q23)--a cytogenetic, morphologic, immunophenotypic and clinical study of 183 cases. European 11q23 Workshop participants

A total of 183 hematologic malignancies with t(4;11)(q21;q23), including five variant translocations, were collected by the Workshop. Clinical, morphologic and immunophenotypic features were compiled, and karyotypes with variant t(4;11) or secondary chromosomal aberrations were reviewed. All cases were acute leukemias (AL): 173 acute lymphoblastic leukemias (ALL), six acute myeloid leukemias (AML), three unclassifiable AL, and one biphenotypic AL. Ten patients had treatment-associated AL. Females were overrepresented (104 vs 79) and the age distribution was clearly nonrandom; 34% of the cases occurred in infants below the age of 12 months. The remaining AL were evenly distributed among the other age groups, with the oldest patient being 79 years old. An increased white blood cell count (WBC) was reported in more than 90% of the cases, with hyperleukocytosis (> or =100 x 10(9)/l) in 64%. Additional chromosomal changes were detected in 55 (30%) cases, most often gain of the X chromosome, i(7)(q10), and trisomy 8, with frequent breakpoints in 1p36, 1q21, 7q10, 11p15, 12p13, 17p11, and 17p10. All recurrent secondary changes resulted in genomic imbalances, in particular gains of 1q, 7q, 8, and X and losses of 7p and 17p. Event-free and overall survival (EFS and OS) could be ascertained in 170 and 171 patients, respectively. Kaplan-Meier estimates of EFS and OS showed no differences with regard to gender, WBC, or presence of secondary chromosomal abnormalities, and there was no increase of EFS or OS among the 55 cases that had undergone bone marrow transplantation. However, age had an important prognostic impact, with significantly (P < 0.0001) longer EFS and OS in children 2-9 years old than among infants and younger children, patients aged between 10 and 39 years and older adults.     

Clonal karyotypic abnormalities of the hereditary multiple exostoses chromosomal loci 8q24.1 (EXT1) and 11p11-12 (EXT2) in patients with sporadic and hereditary osteochondromas

BACKGROUND: Osteochondroma most frequently arises sporadically and as a solitary lesion, but also may arise as multiple lesions characterizing the autosomal dominant disorder hereditary multiple exostoses (HME) and the contiguous gene syndromes Langer-Giedion and DEFECT-11 syndromes. HME is genetically heterogeneous with association of three loci including 8q24.1 (EXT1), 11p11-12 (EXT2), and 19p (EXT3). Constitutional chromosomal microdeletions of 8q24.1 and 11p11-12 are features of the Langer-Giedion and DEFECT-11 syndromes, respectively. Cytogenetic studies of osteochondroma are rare. METHODS: Cytogenetic analysis was performed on 34 osteochondroma specimens from 22 patients with sporadic lesions and 4 patients with HME utilizing standard methodologies. Fluorescence in situ hybridization with chromosome specific probes was performed on three cases to define structural rearrangements further. RESULTS: Clonal abnormalities were detected in ten cases. Notably, deletion of 11p11-13 was observed in one case (a sporadic tumor) and loss or rearrangement of 8q22-24.1 in eight cases (seven sporadic and one hereditary tumor). CONCLUSIONS: These findings: 1) confirm previous observations of 8q24.1 karyotypic anomalies in sporadic osteochondroma, 2) reveal the presence of somatic chromosomal anomalies in hereditary osteochondromata, 3) suggest that similar to hereditary lesions, sporadic osteochondromas also are genetically heterogeneic (involvement of both 8q24.1 and 11p11-12), and 4) support the hypothesis that loss or mutation of EXT1 and EXT2, two putative tumor suppressor genes, may be important in the pathogenesis of sporadic as well as hereditary osteochondromata.