Probabilistic and deductive reasoning in the human brain.

Reasoning is a process of inference from given premises to new conclusions. Deductive reasoning is truth-preserving and conclusions can only be either true or false. Probabilistic reasoning is based on degrees of belief and conclusions can be more or less likely. While deductive reasoning requires people to focus on the logical structure of the inference and ignore its content, probabilistic reasoning requires the retrieval of prior knowledge from memory. Recently, however, some researchers have denied that deductive reasoning is a faculty of the human mind. What looks like deductive inference might actually also be probabilistic inference, only with extreme probabilities. We tested this assumption in an fMRI experiment with two groups of participants: one group was instructed to reason deductively, the other received probabilistic instructions. They could freely choose between a binary and a graded response to each problem. The conditional probability and the logical validity of the inferences were systematically varied. Results show that prior knowledge was only used in the probabilistic reasoning group. These participants gave graded responses more often than those in the deductive reasoning group and their reasoning was accompanied by activations in the hippocampus. Participants in the deductive group mostly gave binary responses and their reasoning was accompanied by activations in the anterior cingulate cortex, inferior frontal cortex, and parietal regions. These findings show that (1) deductive and probabilistic reasoning rely on different neurocognitive processes, (2) people can suppress their prior knowledge to reason deductively, and (3) not all inferences can be reduced to probabilistic reasoning.

The effects of creatine supplementation on cognitive performance-a randomised controlled study.

BACKGROUND: Creatine is an organic compound that facilitates the recycling of energy-providing adenosine triphosphate (ATP) in muscle and brain tissue. It is a safe, well-studied supplement for strength training. Previous studies have shown that supplementation increases brain creatine levels, which might increase cognitive performance. The results of studies that have tested cognitive performance differ greatly, possibly due to different populations, supplementation regimens, and cognitive tasks. This is the largest study on the effect of creatine supplementation on cognitive performance to date. METHODS: Our trial was preregistered, cross-over, double-blind, placebo-controlled, and randomised, with daily supplementation of 5 g for 6 weeks each. We tested participants on Raven's Advanced Progressive Matrices (RAPM) and on the Backward Digit Span (BDS). In addition, we included eight exploratory cognitive tests. About half of our 123 participants were vegetarians and half were omnivores. RESULTS: Bayesian evidence supported a small beneficial effect of creatine. The creatine effect bordered significance for BDS (p = 0.064, η2P = 0.029) but not RAPM (p = 0.327, η2P = 0.008). There was no indication that creatine improved the performance of our exploratory cognitive tasks. Side effects were reported significantly more often for creatine than for placebo supplementation (p = 0.002, RR = 4.25). Vegetarians did not benefit more from creatine than omnivores. CONCLUSIONS: Our study, in combination with the literature, implies that creatine might have a small beneficial effect. Larger studies are needed to confirm or rule out this effect. Given the safety and broad availability of creatine, this is well worth investigating; a small effect could have large benefits when scaled over time and over many people. TRIAL REGISTRATION: The trial was prospectively registered (drks.de identifier: DRKS00017250, https://osf.io/xpwkc/ ).

How to think about and do successful research What you probable did not learn when you first entered the laboratory.

There is a logic to doing successful research, but graduate students and indeed postdoctoral fellows and young independent investigators often learn it apprentice style, by experience. The purpose of this essay is to provide the product of that experience and advice that I have found useful to young researchers as they begin their training and careers.

Conducting and Writing Quantitative and Qualitative Research.

Comprehensive knowledge of quantitative and qualitative research systematizes scholarly research and enhances the quality of research output. Scientific researchers must be familiar with them and skilled to conduct their investigation within the frames of their chosen research type. When conducting quantitative research, scientific researchers should describe an existing theory, generate a hypothesis from the theory, test their hypothesis in novel research, and re-evaluate the theory. Thereafter, they should take a deductive approach in writing the testing of the established theory based on experiments. When conducting qualitative research, scientific researchers raise a question, answer the question by performing a novel study, and propose a new theory to clarify and interpret the obtained results. After which, they should take an inductive approach to writing the formulation of concepts based on collected data. When scientific researchers combine the whole spectrum of inductive and deductive research approaches using both quantitative and qualitative research methodologies, they apply mixed-method research. Familiarity and proficiency with these research aspects facilitate the construction of novel hypotheses, development of theories, or refinement of concepts.

Both sheep and goats can solve inferential by exclusion tasks.

Despite the domestication of sheep and goats by humans for several millennia, we still lack comparative data on their cognitive capacity. Comparing the cognitive skills of farm animals can help understand the evolution of cognition. In this study, we compared the performances of sheep and goats in inference by exclusion tasks. We implemented two tasks, namely a cup task and a tube task, to identify whether success in solving the task could be attributed to either low-level mechanisms (avoiding the empty location strategy) or to deductive reasoning (if two possibilities A and B, but not A, then it must be B). In contrast to a previous study comparing goats and sheep in a cup task, we showed that both species solved the inferential condition with high success rates. In the tube task, performances could not be explained by alternative strategies such as avoiding the empty tube or preferring the bent tube. When applying a strict set of criteria concerning responses in all conditions and controlling for the potential effects of experience, we demonstrate that two individuals, a goat and a sheep, fulfil these criteria. This suggests that sheep and goats are able to make inferences based on deductive reasoning.

A Cortical Surface-Based Meta-Analysis of Human Reasoning.

Recent advances in neuroimaging have augmented numerous findings in the human reasoning process but have yielded varying results. One possibility for this inconsistency is that reasoning is such an intricate cognitive process, involving attention, memory, executive functions, symbolic processing, and fluid intelligence, whereby various brain regions are inevitably implicated in orchestrating the process. Therefore, researchers have used meta-analyses for a better understanding of neural mechanisms of reasoning. However, previous meta-analysis techniques include weaknesses such as an inadequate representation of the cortical surface's highly folded geometry. Accordingly, we developed a new meta-analysis method called Bayesian meta-analysis of the cortical surface (BMACS). BMACS offers a fast, accurate, and accessible inference of the spatial patterns of cognitive processes from peak brain activations across studies by applying spatial point processes to the cortical surface. Using BMACS, we found that the common pattern of activations from inductive and deductive reasoning was colocalized with the multiple-demand system, indicating that reasoning is a high-level convergence of complex cognitive processes. We hope surface-based meta-analysis will be facilitated by BMACS, bringing more profound knowledge of various cognitive processes.

Find extra options or reason badly: An investigation of children's reasoning with incompatibility statements.

The false dilemma or dichotomy is a logical fallacy that occurs when interlocuters accept the premises in an incompatibility statement as being jointly exhaustive (i.e., leaving no third option), whereas that is in fact not the case. Brisson et al. [Memory & Cognition (2018), Vol. 46, pp. 657-670] investigated this fallacy in an adult sample and discovered a content effect that influenced participants' performance. The current study aimed to elaborate on these findings by establishing whether similar patterns could be observed with children. A number of age-appropriate incompatibility premises were constructed. For every item, four different inferential problems were presented (Affirm First, Affirm Second, Deny First, and Deny Second) with three potential answers to choose from (X, not X, or uncertainty regarding X). A sample of 192 volunteer children, with ages ranging from 8 to 13 years, was collected. Statistical analysis showed no significant effect for participants' age but did reveal main effects for premise validity and the amount of available "third options" (possibilities outside of the presented dichotomy). These results are a clear replication of the general effects on adults found by Brisson et al. Affirm inferences were also easy for children, Deny inferences were difficult (even more so than for adults), and content had a profound effect on participants' performance. Whenever more third options could be generated, children were less likely to fall into the false dilemma fallacy. Our findings thus further support the idea that reasoning with incompatibilities is influenced by the same semantic retrieval processes that have been previously related to human conditional reasoning.

Deductive Reasoning and Working Memory Skills in Individuals with Blindness.

Deductive reasoning and working memory are integral parts of executive functioning and are important skills for blind people in everyday life. Despite the importance of these skills, the influence of visual experience on reasoning and working memory skills, as well as on the relationship between these, is unknown. In this study, fifteen participants with congenital blindness (CB), fifteen with late blindness (LB), fifteen sighted blindfolded controls (SbfC), and fifteen sighted participants performed two tasks of deductive reasoning and two of working memory. We found that while the CB and LB participants did not differ in their deductive reasoning abilities, the CB group performed worse than the sighted controls, and the LB group performed better than the SbfC group. Those with CB outperformed all the other groups in both of the working memory tests. Working memory is associated with deductive reasoning in all three visually impaired groups, but not in the sighted group. These findings suggest that deductive reasoning is not a uniform skill, and that it is associated with visual impairment onset, the level of reasoning difficulty, and the degree of working memory load.

Neurocognitive basis of deductive reasoning in children varies with parental education.

The neurocognitive basis of elementary academic skills varies with parental socioeconomic status (SES). Little is known, however, about SES-related differences underlying higher-order cognitive skills that are critical for school success, such as reasoning. Here we used fMRI to examine how the neurocognitive basis of deductive reasoning varies as a function of parental education in school-aged children. Higher parental education was associated with greater reliance on the left inferior frontal gyrus when solving set-inclusion problems, consistent with other work suggesting that these problems might more heavily rely on verbal systems in the brain. In addition, children who are at the lower end of the parental education continuum, but have higher nonverbal skills relied on right parietal areas to a greater degree than their peers for solving set-inclusion problems. Finally, lower parental education children with higher verbal or nonverbal skill engaged dorsolateral prefrontal regions to a greater degree for set-inclusion and linear-order relations than their peers. These findings suggest that children with lower parental education rely on spatial and cognitive control mechanisms to achieve parity with their peers with parents who have more education. Better understanding variability in the neurocognitive networks that children recruit as a function of their parental factors might benefit future individualized interventions that best match children's characteristics.

Reasoning strategies and semantic memory effects in deductive reasoning.

Growing evidence supports the dual-strategy model, which suggests that reasoners have access to both a statistical and a counterexample reasoning strategy. In this paper, we explore further the processes underlying strategy use. We report three studies, the aim of which was to clarify the relation between this model and two forms of everyday reasoning. One of the most robust effects found with conditional reasoning with meaningful premises is the effect of alternative antecedents on the endorsement of AC and DA inferences. In a first study, we presented participants with conditional reasoning problems having more or fewer accessible alternatives as well as our dual-strategy diagnostic questionnaire. As hypothesized, results showed that strategy use had an independent effect on the inferences made with the AC and DA forms, over and above the effect of the number of antecedents, but was not related to responding to the MP and the MT forms. In a second study, we found that this relation extended to reasoning from an incompatibility statement. Finally, a third study showed that this relationship did not hold with probabilistic rather than logical response instructions, suggesting that the way reasoners transform a probabilistic evaluation into a dichotomous judgment is a key determinant of strategy use.

Investigation of adolescents' developmental stages in deductive reasoning: An application of a specialized confirmatory mixture IRT approach.

In this paper, we propose a specialized confirmatory mixture IRT model to analyze complex cognitive assessment data that is designed to evaluate adolescents' developmental stages in deductive reasoning. The model is specified for the following purposes: (1) to measure multiple deductive reasoning traits, (2) to identify adolescents' differential developmental stages based on their ability levels in the multiple dimensions, (3) to quantify the differences in dimension-specific performance between developmental stages, and (4) to examine the difficulty levels of test design factors. A Bayesian estimation of the model is described. The overall goodness-of-fit of the model is assessed as well as its parameter recovery to validate the application of the model to the data.

Effective decision-making: applying the theories to nursing practice.

Many theories have been proposed for the decision-making conducted by nurses across all practices and disciplines. These theories are fundamental to consider when reflecting on our decision-making processes to inform future practice. In this article three of these theories are juxtaposed with a case study of a patient presenting with an ST-segment elevation myocardial infarction (STEMI). These theories are descriptive, normative and prescriptive, and will be used to analyse and interpret the process of decision-making within the context of patient assessment.

Testing the deductive inferential account of blocking in causal learning.

The sensitivity of the blocking effect to outcome additivity pretraining has been used to argue that the phenomenon is the result of deductive inference, and to draw general conclusions about the nature of human causal learning. In two experiments, we manipulated participants' assumptions about the additivity of the outcome using pretraining before a typical blocking procedure. Ratings measuring causal judgments, confidence, and expected severity of the outcome were used concurrently to investigate how pretraining affected assumptions of outcome additivity and blocking. In Experiment 1, additive pretraining led to lower causal ratings and higher confidence ratings of the blocked cue, relative to control cues, consistent with the notion that additive pretraining encourages deductive reasoning. However, Experiments 1 and 2 showed that removing additivity assumptions through nonadditive pretraining had no impact on a statistically reliable blocking effect observed in a blocking procedure with no pretraining. We found no evidence that the blocking effect in the absence of pretraining was related to the participants' assumptions about the additivity of the outcome. Although additive pretraining may enhance blocking by encouraging deductive reasoning about the blocked cue, the evidence suggests that blocking in causal learning is not reliant on this reasoning and that humans do not readily engage in deduction merely because they possess the assumptions that permit its use.

Solving the Diagnostic Challenge: A Patient-Centered Approach.

Arriving at an agreed-on and valid explanation for a clinical problem is important to patients as well as to clinicians. Current theories of how clinicians arrive at diagnoses, such as the threshold approach and the hypothetico-deductive model, do not accurately describe the diagnostic process in general practice. The problem space in general practice is so large and the prior probability of each disease being present is so small that it is not realistic to limit the diagnostic process to testing specific diagnoses on the clinician's list of possibilities. Here, new evidence is discussed about how patients and clinicians collaborate in specific ways, in particular, via a process that can be termed inductive foraging, which may lead to information that triggers a diagnostic routine. Navigating the diagnostic challenge and using patient-centered consulting are not separate tasks but rather synergistic.

Reasoning from an incompatibility: False dilemma fallacies and content effects.

In the present studies, we investigated inferences from an incompatibility statement. Starting with two propositions that cannot be true at the same time, these inferences consist of deducing the falsity of one from the truth of the other or deducing the truth of one from the falsity of the other. Inferences of this latter form are relevant to human reasoning since they are the formal equivalent of a discourse manipulation called the false dilemma fallacy, often used in politics and advertising in order to force a choice between two selected options. Based on research on content-related variability in conditional reasoning, we predicted that content would have an impact on how reasoners treat incompatibility inferences. Like conditional inferences, they present two invalid forms for which the logical response is one of uncertainty. We predicted that participants would endorse a smaller proportion of the invalid incompatibility inferences when more counterexamples are available. In Study 1, we found the predicted pattern using causal premises translated into incompatibility statements with many and few counterexamples. In Study 2A, we replicated the content effects found in Study 1, but with premises for which the incompatibility statement is a non-causal relation between classes. These results suggest that the tendency to fall into the false dilemma fallacy is modulated by the background knowledge of the reasoner. They also provide additional evidence on the link between semantic information retrieval and deduction.

The capacity to generate alternative ideas is more important than inhibition for logical reasoning in preschool-age children.

There is little consensus about the nature of logical reasoning and, equally important, about how it develops. To address this, we looked at the early origins of deductive reasoning in preschool children. We examined the contribution of two factors to the reasoning ability of very young children: inhibitory capacity and the capacity to generate alternative ideas. In a first study, a total of 32 preschool children were all given generation, inhibition, and logical reasoning measures. Logical reasoning was measured using knowledge-based premises such as "All dogs have legs," and two different inferences: modus ponens and affirmation of the consequent. Results revealed that correctly reasoning with both inferences is not related to the measure of inhibition, but is rather related to the capacity to generate alternative ideas. In a second study, 32 preschool children were given either the generation or the inhibition task before the logical reasoning measure. Results showed that receiving the generation task beforehand significantly improved logical reasoning compared to the inhibition task given beforehand. Overall, these results provide evidence for the greater importance of idea generation in the early development of logical reasoning.

When fast logic meets slow belief: Evidence for a parallel-processing model of belief bias.

Two experiments pitted the default-interventionist account of belief bias against a parallel-processing model. According to the former, belief bias occurs because a fast, belief-based evaluation of the conclusion pre-empts a working-memory demanding logical analysis. In contrast, according to the latter both belief-based and logic-based responding occur in parallel. Participants were given deductive reasoning problems of variable complexity and instructed to decide whether the conclusion was valid on half the trials or to decide whether the conclusion was believable on the other half. When belief and logic conflict, the default-interventionist view predicts that it should take less time to respond on the basis of belief than logic, and that the believability of a conclusion should interfere with judgments of validity, but not the reverse. The parallel-processing view predicts that beliefs should interfere with logic judgments only if the processing required to evaluate the logical structure exceeds that required to evaluate the knowledge necessary to make a belief-based judgment, and vice versa otherwise. Consistent with this latter view, for the simplest reasoning problems (modus ponens), judgments of belief resulted in lower accuracy than judgments of validity, and believability interfered more with judgments of validity than the converse. For problems of moderate complexity (modus tollens and single-model syllogisms), the interference was symmetrical, in that validity interfered with belief judgments to the same degree that believability interfered with validity judgments. For the most complex (three-term multiple-model syllogisms), conclusion believability interfered more with judgments of validity than vice versa, in spite of the significant interference from conclusion validity on judgments of belief.

The logic-bias effect: The role of effortful processing in the resolution of belief-logic conflict.

According to the default interventionist dual-process account of reasoning, belief-based responses to reasoning tasks are based on Type 1 processes generated by default, which must be inhibited in order to produce an effortful, Type 2 output based on the validity of an argument. However, recent research has indicated that reasoning on the basis of beliefs may not be as fast and automatic as this account claims. In three experiments, we presented participants with a reasoning task that was to be completed while they were generating random numbers (RNG). We used the novel methodology introduced by Handley, Newstead & Trippas (Journal of Experimental Psychology: Learning, Memory, and Cognition, 37, 28-43, 2011), which required participants to make judgments based upon either the validity of a conditional argument or the believability of its conclusion. The results showed that belief-based judgments produced lower rates of accuracy overall and were influenced to a greater extent than validity judgments by the presence of a conflict between belief and logic for both simple and complex arguments. These findings were replicated in Experiment 3, in which we controlled for switching demands in a blocked design. Across all three experiments, we found a main effect of RNG, implying that both instructional sets require some effortful processing. However, in the blocked design RNG had its greatest impact on logic judgments, suggesting that distinct executive resources may be required for each type of judgment. We discuss the implications of our findings for the default interventionist account and offer a parallel competitive model as an alternative interpretation for our findings.

Hippocampal lesion and transitive inference: dissociation of inference-based and reinforcement-based strategies in pigeons.

A typical nonverbal transitive inference task (TI) consists of several overlapping discriminations (A+ B-, B+ C-, C+ D-, D+ E-, where letters indicate stimuli and pluses and minuses denote reinforcement and nonreinforcement). A choice of stimulus B in a novel pair BD is interpreted as indicative of a TI (if B > C and C > D, then B > D). Although hippocampus has been implicated in nonverbal TI, it is not clear whether it simply maintains memory of associative values or stores an ordered representation of stimuli. We investigated the effect of hippocampal lesion on TI in pigeons while controlling reinforcement history so that reliance on associative values would lead to a choice of a stimulus D in the pair BD instead of a choice of a stimulus B expected by inferential mechanisms. Prior to the lesion, some of the pigeons (relational group; n = 4) have selected B over D indicating TI, while other birds (associative group; n = 6) chose D over B suggesting reliance on associative values. Hippocampal lesion had no effect on postlesion performance in associative group. In contrast, the relational group that preferred stimulus B in a pair BD before lesion showed a near-chance performance after the lesion. Our results demonstrate that hippocampus may be involved in creating a representation of an ordered series of the stimuli instead of maintaining reinforcement history of each stimulus. In addition, we provide a behavioral procedure suitable for dissociating different behavioral strategies used to solving TI task. Finally, we show for the first time the involvement of avian hippocampus in the task that is not explicitly spatial in nature. These results further confirm the notion that avian hippocampus is functionally analogous to mammalian hippocampus despite the significant differences in their anatomy.

Distributed neural representations of logical arguments in school-age children.

Children's understanding of linear-order (e.g., Dan is taller than Lisa, Lisa is taller than Jess) and set-inclusion (i.e., All tulips are flowers, All flowers are plants) relationships is critical for the acquisition of deductive reasoning, that is, the ability to reach logically valid conclusions from given premises. Behavioral and neuroimaging studies in adults suggest processing differences between these relations: While arguments that involve linear-orders may be preferentially associated with spatial processing, arguments that involve set-inclusions may be preferentially associated with verbal processing. In this study, we used functional magnetic resonance imaging to investigate whether these processing differences appear during the period of elementary school in development. Consistent with previous studies in adults, we found that arguments that involve linear-order and set-inclusion relationships preferentially involve spatial and verbal brain mechanisms (respectively) in school-age children (9-14 year olds). Because this neural sensitivity was not related to age, it likely emerges before the period of elementary education. However, the period of elementary education might play an important role in shaping the neural processing of logical reasoning, as indicated by developmental changes in frontal and parietal regions that were dependent on the type of relation.