The mental representation of integers: an abstract-to-concrete shift in the understanding of mathematical concepts

Mathematics has a level of structure that transcends untutored intuition. What is the cognitive representation of abstract mathematical concepts that makes them meaningful? We consider this question in the context of the integers, which extend the natural numbers with zero and negative numbers. Participants made greater and lesser judgments of pairs of integers. Experiment 1 demonstrated an inverse distance effect: When comparing numbers across the zero boundary, people are faster when the numbers are near together (e.g., −1 vs. 2) than when they are far apart (e.g., −1 vs. 7). This result conflicts with a straightforward symbolic or analog magnitude representation of integers. We therefore propose an analog-x hypothesis: Mastering a new symbol system restructures the existing magnitude representation to encode its unique properties. We instantiate analog-x in a reflection model: The mental negative number line is a reflection of the positive number line. Experiment 2 replicated the inverse distance effect and corroborated the model. Experiment 3 confirmed a developmental prediction: Children, who have yet to restructure their magnitude representation to include negative magnitudes, use rules to compare negative numbers. Taken together, the experiments suggest an abstract-to-concrete shift: Symbolic manipulation can transform an existing magnitude representation so that it incorporates additional perceptual-motor structure, in this case symmetry about a boundary. We conclude with a second symbolic-magnitude model that instantiates analog-x using a feature-based representation, and that begins to explain the restructuring process.     

腹腔镜胃癌手术的应用进展

腹腔镜胃癌手术是目前胃癌外科的热点与发展趋势,在早期采取腹腔镜手术的比例逐渐增多,早期胃癌的良好的临床疗效促进了腹腔镜进一步应用到进展期胃癌手术当中。本文概述了腹腔镜在早期胃癌及进展期胃癌的应用与进展,以及未来腹腔镜胃癌手术发展需要努力的方向。     

早期子宫颈癌根治性子宫颈切除术的临床应用

近年来子宫颈癌发病率呈现上升及年轻化趋势,年轻宫颈癌患者需要保留生育功能。随着新术式和腹腔镜的发展,子宫颈根治性切除术作为治疗早期宫颈癌的一种新的治疗方法,严格掌握其手术实施的适应证,结合医学伦理学和循证医学的原则,既达到了根治性的目的,又充分考虑到生育功能的保留。因此子宫颈根治性切除术是一种可行、有效、合理的手术方式。     

The relationship between the objective identification threshold and priming effects does not provide a definitive boundary between conscious and unconscious perceptual processes

The Objective Threshold/Strategic Model (OT/S) proposes that strong, qualitative inferences of unconscious perception can be made if the relationship between perceptual sensitivity (typically priming effects) and stimulus visibility is nonlinear and nonmonotonic. The model proposes a nadir in priming effects at the objective identification threshold (identification d′ = 0). These predictions were tested with masked semantic priming and repetition priming of a lexical decision task. The visibility of the prime stimuli was systematically varied above and below the objective identification threshold. The obtained relationship between prime visibility and priming facilitation was nonlinear, but the results failed to confirm a nadir in priming effects at the objective identification threshold. We conclude that the objective identification threshold does not necessarily indicate the point where presumably unconscious priming effects might be inhibited by conscious cognitive processes.     

Anti‐Immigrant Propaganda by Radical Right Parties and the Intellectual Performance of Adolescents

In recent years radical right political parties have become a substantial electoral force in many countries around the world. Based on the vision of a mono‐ethnic state, anti‐immigration is these parties' core message. Connecting research on discrimination, social exclusion, and social identity threat, it was assumed that this anti‐immigrant propaganda undermines the intellectual performance of immigrant adolescents. In an experiment conducted at Austrian schools, the intelligence test performance of adolescents with an immigration background decreased after they were exposed to radical right election posters whereas ethnic majority adolescents remained unaffected. The results further suggest that individuals with a strong ethnic minority identity are less vulnerable to the detrimental impact of the radical right propaganda.     

Hemispheric asymmetries in meaning selection: Evidence from the disambiguation of homophonic vs. heterophonic homographs

Research investigating hemispheric asymmetries in meaning selection using homophonic homographs (e.g., bank), suggests that the left hemisphere (LH) quickly selects contextually relevant meanings, whereas the right hemisphere (RH) maintains a broader spectrum of meanings including those that are contextually irrelevant (e.g., Faust & Chiarello, 1998). The present study investigated cerebral asymmetries in maintaining the multiple meanings of two types of Hebrew homographs: homophonic homographs and heterophonic homographs (e.g., tear). Participants read homographs preceded by a biasing, or a non-biasing sentential context, and performed a lexical decision task on targets presented laterally, 1000 ms after the onset of the sentence-final ambiguous prime. Targets were related to either the dominant or the subordinate meaning of the preceding homograph, or unrelated to it. When targets were presented in the LVF/RH, dominant and subordinate meanings, of both types of homographs, were retained only when they were supported by context. In a non-biasing context, only dominant meanings of homophonic homographs were retained. Alternatively, when targets were presented in the RVF/LH, priming effects for homophonic homographs were only evident when meanings were supported by both context and frequency (i.e., when context favored the dominant meaning). In contrast, heterophonic homographs resulted in activation of dominant meanings, in all contexts, and activation of subordinate meanings, only in subordinate-biasing contexts. The results challenge the view that a broader spectrum of meanings is maintained in the right than in the left hemisphere and suggest that hemispheric differences in the time course of meaning selection (or decay) may be modulated by phonology.     

The effects of total sleep deprivation on semantic priming: Event-related potential evidence for automatic and controlled processing strategies

There is general consensus that performance on a number of cognitive tasks deteriorates following total sleep deprivation. At times, however, subjects manage to maintain performance. This may be because of an ability to switch cognitive strategies including the exertion of compensatory effort. The present study examines the effects of total sleep deprivation on a semantic word priming task. Word priming is unique because it can be carried out using different strategies involving either automatic, effortless or controlled, effortful processing. Twelve subjects were presented with word pairs, a prime and a target, that were either highly semantically associated (cat…dog), weakly associated (cow…barn) or unassociated (apple…road). In order to increase the probability of the use of controlled processing following normal sleep, the subject’s task was to determine if the target word was semantically related to the prime. Furthermore, the time between the offset of the prime and the onset of the target was relatively long, permitting the use of an effortful, expectancy-predictive strategy. Event-related potentials (ERPs) were recorded from 64 electrode sites. After normal sleep, RTs were faster and accuracy higher to highly associated targets; this performance advantage was also maintained following sleep deprivation. A large negative deflection, the N400, was larger to weakly associated and unassociated targets in both sleep-deprived and normal conditions. The overall N400 was however larger in the normal sleep condition. Moreover, a long-lasting negative slow wave developed between the offset of the prime and the onset of the target. These physiological measures are consistent with the use of an effortful, predictive strategy following normal sleep but an automatic, effortless strategy following total sleep deprivation. A picture priming task was also run. This task benefits less from the use of a predictive strategy. Accordingly, in this task, ERPs following the target did not differ as a function of the amount of sleep.     

Intention,Emotion, and Action: A Neural Theory Based on Semantic Pointers

We propose a unified theory of intentions as neural processes that integrate representations of states of affairs, actions, and emotional evaluation. We show how this theory provides answers to philosophical questions about the concept of intention, psychological questions about human behavior, computational questions about the relations between belief and action, and neuroscientific questions about how the brain produces actions. Our theory of intention ties together biologically plausible mechanisms for belief, planning, and motor control. The computational feasibility of these mechanisms is shown by a model that simulates psychologically important cases of intention.     

Constituent order and semantic parallelism in online comprehension: Eye-tracking evidence from German

Reading times for the second conjunct of and-coordinated clauses are faster when the second conjunct parallels the first conjunct in its syntactic or semantic (animacy) structure than when its structure differs (Frazier, Munn, & Clifton, 2000; Frazier, Taft, Roeper, & Clifton, 1984). What remains unclear, however, is the time course of parallelism effects, their scope, and the kinds of linguistic information to which they are sensitive. Findings from the first two eye-tracking experiments revealed incremental constituent order parallelism across the board—both during structural disambiguation (Experiment 1) and in sentences with unambiguously case-marked constituent order (Experiment 2), as well as for both marked and unmarked constituent orders (Experiments 1 and 2). Findings from Experiment 3 revealed effects of both constituent order and subtle semantic (noun phrase similarity) parallelism. Together our findings provide evidence for an across-the-board account of parallelism for processing and-coordinated clauses, in which both constituent order and semantic aspects of representations contribute towards incremental parallelism effects. We discuss our findings in the context of existing findings on parallelism and priming, as well as mechanisms of sentence processing.