Mechanisms of theory formation in young children

Research suggests that by the age of five, children have extensive causal knowledge, in the form of intuitive theories. The crucial question for developmental cognitive science is how young children are able to learn causal structure from evidence. Recently, researchers in computer science and statistics have developed representations (causal Bayes nets) and learning algorithms to infer causal structure from evidence. Here we explore evidence suggesting that infants and children have the prerequisites for making causal inferences consistent with causal Bayes net learning algorithms. Specifically, we look at infants and children's ability to learn from evidence in the form of conditional probabilities, interventions and combinations of the two.     

Merging Inference and Conjecture by Information

The intuitive notion of a binary relation on information-bearers, comparingthem with respect to their closeness to the available information, is oftenconstrued in terms of comparing their symmetric difference with, orcompositional similarity to, the available information. This happens forinstance in some treatments of verisimilitude. We expound an abstractmathematical rendering of the relevant data-dependent relation in theframework of Boolean algebras. For every element t of a Boolean algebra B we construct the t-modulated Boolean algebra B_tin which the order relation represents `is at most as compatible with t as' or `is at best as similar to t as'. In the case of Lindenbaum-Tarskialgebras, t expresses the available information, and the compatibilityrelation turns out to be an entwinement of inferential and conjecturalrelations. It is just classical entailment when no information is available(i.e., when t is logically true) and becomes more boldly abductive themore information is available. The rich algebraic structures of a Boolean algebra –- including its Boolean group structures –- play a significant role in this combination of deduction and abduction and also induce cautious anddaring variants of the compatibility relation. Links with the literature onverisimilitude, abduction, and related topics are indicated.     

Fractional Design Wizard: A computer program for cost-effective experimental research design

The computer program Fractional Design Wizard creates fractional factorial designs that are cost-effective and especially useful for discarding irrelevant factors from a large number of possible candidates. The program is intended for researchers who are relativelynew to the field of fractional design and who want to acquaint themselves with the use of fractions for the reduction of large experimental designs. Fractional designs allow estimation of main effects, and sometimes two-way interactions, without one’s having to examine all treatment conditions. The program needs Microsoft Windows 95 or better and 32 MB of memory. In a step-by-step fashion, the user can specify the required properties of the fractional design. When there are more valid designs, the user can generate these successively If necessary the user can go back to diminish the requirements. The output can be copied, printed, and saved. The program generates all the information that is needed for the use and interpretation of fractional designs. A help file explains the use of the program and also the purpose, the analysis, and the interpretation of fractional designs. The program, which is written in Object Pascal, is available as freeware on www.fss.uu.nl/ms/hl/fracdes.htm.     

Allgemeine Sinnesphysiologie

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Orthography shapes the perception of speech: The consistency effect in auditory word recognition

Inconsistency in the spelling-to-sound mapping hurts visual word perception and reading aloud (i.e., the traditional consistency effect). In the present experiment, we found a consistency effect in auditory word perception: Words with phonological rimes that could be spelled in multiple ways produced longer auditory lexical decision latencies and more errors than did words with rimes that could be spelled only one way. This finding adds strong support to the claim that orthography affects the perception of spoken words. This effect was predicted by a model that assumes a coupling between orthography and phonology that is functional in both visual and auditory word perception.     

SSRAT: The processing of rating scales for the determination of two-dimensional sociometric status

SSRAT is an MS-DOS computer program for two-dimensional sociometric status determination with rating scales. It classifies members of a population into five sociometric status groups, using 3-, 5-, 7-, or 9-point ratings in matrices of assessors and assessed. The processing of rating scales instead of nominations offers several advantages, including increased variability and reliability of the resulting scores. SSRAT is built on the null hypothesis of conditional random attribution of ratings, according to the particular probability distribution of an assessor. Output is available in the form of an ASCII SPSS data file for further statistical processing. Recent studies show that SSRAT, in comparison with nomination methods, (1) is superior in determining popular persons while it detects rejected persons as well, and (2) probably yields classifications that have a higher temporal stability.     

Tryptophan metabolism research in oligophrenic children. 4.: Activity and possibility of activating hepatic kynureninase after vitamin B6 treatment]

In 8 selected test persons of the 3rd series of experiments who were showing signs of pathological kynureninase activity, hepatic kynureninase was again established after 3 week's treatment with large doses of vitamin B6. The enormous in-vivo activation of the kynureninasis established goes to prove that apoenzyme synthesis may be stimulated by pyridoxine. On the basis of these results and the relative frequency of disorders dependent on B6, the question arises whether children from endangered families should not be given prophylactic vitamin B6 treatment from birth.     

Foreground and background in dynamic spatial orientation

The dependency of visually induced self-motion sensation upon the density of moving contrasts as well as upon additional stationary contrasts in the foreground or background was investigated. Using two different optokinetic stimuli, a disk rotating in the frontoparallel plane, and the projection of horizontally moving stripes onto a cylindrical screen, it was found that: (1) visually induced self-motion depends upon the density of moving contrasts randomly distributed within the visual field and, with a single contrast area of 1/4 %, is saturated when about 30% of the visual field is moving; (2) additional stationary contrasts inhibit visually induced serf-motion, proportional to their density; and (3) the location in depth of the stationary contrasts has a significant effect upon this inhibition. Their effect is considerable when located in the background of the moving stimuli but weak when appearing in the foreground. It is concluded that dynamic visual spatial orientation relies mainly on information from the seen periphery, both retinal and depth.     

The effect of non-verbal information on the recall of negation

The influence of non-verbal information on storage of different versions of negated sentences was investigated in a one-trial learning experiment. The negation governed either the subject, the object, or the predicate of the sentence. One group was presented with the sentences together with pictures. Another group the sentences only. The picture which was shown with a sentence represented the sentence content with an alternative for the negated concept. It was found that pictorial information had an effect on the recall of the sentences and that this effect is different for the different sentence versions.