A procedural theory of eye movements in doing arithmetic

A procedural theory of eye movement that accounts for main features of the stochastic behavior of eye-fixation durations and direction of movement of saccades in the process of solving arithmetic exercises of addition and subtraction is presented. The best-fitting distribution of fixation durations with a relatively simple theoretical justification consists of a mixture of an exponential distribution and the convolution of two exponential distributions. The eye movements themselves were found to approximate a random walk that fits rather closely in both adult and juvenile subjects the motion postulated by the normative algorithm ordinarily taught in schools. Certain structural features of addition and subtraction exercises, such as the number of columns, the presence or absence of a carry or a borrow, are well known to affect their difficulty. In this study, regressions on such structural variables were found to account for only a relatively small part of the variation in eye-fixation durations.     

Accommodation fatigue and dark focus: The effects of accommodation-free visual work as assessed by two psychophysical methods

Past studies of accommodation fatigue have yielded inconsistent results, partly because they have not used direct measures of accommodation, and partly because they may have been based on a misleading conception of the nature of accommodation. The dual-innervation theory of accommodation suggests that the resting position of accommodation may be neuromuscular rather than just muscular, and that it lies not at optical infinity, as assumed by older conceptions, but at some intermediate position (dark focus). Among the predictions that may be deduced from this theory is that long-term visual work not requiring active accommodation will not induce fatigue. The present study involved continuous measurements of dark focus for 10 young adults over a 3-h period, using the laser optometer with two psychophysical procedures Ibracketing and staircase. Consistent with the prediction, no changes in dark focus were found, in spite of the demanding visual task. Furthermore, it was found that both psychophysical methods yielded essentially identical results. The practical and theoretical implications of these results are discussed, and recommendations are given regarding situations in which each of the psychophysical methods is likely to be most useful.     

Prophetic criticism,incarnational optimism: On recovering the late Kierkegaard

Actually the revolution is much closer than we think. The last band of free thinkers (Feuerbach and all related to him) has attacked or tackled the matter far more clearly than formerly, for if you look more closely, you will see that they actually have taken upon themselves the task of defending Christianity against contemporary Christians. The point is that established Christendom is demoralized, in the profoundest sense all respect for Christianity's existential commitments has been lost … Now Feuerbach is saying: No, wait a minute—if you are going to be allowed to go on living as you are living, then you also have to admit that you are not Christians … it is wrong of established Christendom to say that Feuerbach is attacking Christianity; it is not true, he is attacking the Christians by demonstrating that their lives do not correspond to the teachings of Christianity … What Christianity needs for certain is traitors … (JP 6523)     

Children's representation of knowledge in verification

Thirty-two children aged 8–9 and 10–11 were asked to perform two statement verification tasks. Task 1 consisted of statements that were likely to elicit an affirmative knowledge representation,You have three eyes, is likely to elicit the representation,I have two eyes. Task 2 consisted of statements that were likely to elicit a negative knowledge of representation,You have a tail, is likely to elicit a negative representation,I do not have a tail. All statements varied in two dimensions, polarity (affirmative vs. negative) and truth value (true vs. false). Negative statements in Task 1 were found to be more difficult for children to verify than those in Task 2. This performance difference was used to infer the form of knowledge representation generated in verifying negative statements.     

Emotionality of encoding activity in face memory

The effects of emotionality of study tasks on face recognition were examined. Subjects made either personality decisions or self-comparisons about the people shown in a series of photographs. The personality traits judged during the encoding tasks had been selected to be either arousing or relatively nonarousing. Face recognition performance was best after an emotional nonself study task, on both immediate and delayed tests. In a companion study examining these manipulations in verbal memory, self-reference study tasks produced the best word recognition, with no difference due to the emotionality of nonself tasks. These results suggest emotionality and self-awareness have different effects on facial and verbal memory. A final study indicated that the effect of emotionality disappeared if it was added to self-reference. As regards self-reference differences in face and verbal memory, this series of experiments seems to rule out an emotionality confounding. It was concluded that self-images are less effective mnemonic aids than the propositional self-concept.     

Further study of the electrophysiological correlates of lexical decision

Discriminations were required between words, pseudohomophones, and visually matched nonwords. Two tasks were employed, one which could be accomplished on the basis of a visual code (the REAL task, involving discrimination between words and both types of nonword) and another necessitating the use of a phonological code (the REAL/PSEUD task, words and pseudohomophones vs. nonwords). ERPs were recorded from three midline sites and from left and right inferior parietal sites. Two principal results were observed, (i) the peak latency of a late positive component, P637, covaried with RT, with variations in latency of around one half the corresponding RT variations, and (ii) the peak-to-peak amplitude of N100-P187 interacted with stimulus and task, such that it was larger for nonwords in the REAL task and words in the REAL/PSEUD task. No taskor stimulus-dependent asymmetries were observed in any ERP component. The P637 latency data support a model of RT variation based on the interaction of changes in parallel response preparation and stimulus evaluation processes. The observations with respect to N100-P187 suggest that ERPs are sensitive to factors related to the early processing of words and word-like visual material.     

A method for identifying eggs laid by individual birds

A method for identifying eggs laid by different subsections or individual members of groups of domestic hens is described. Fat-soluble dyes are placed in gelatin capsules and fed to selected birds. These dyes produce discrete colored bands in the yolks of eggs laid by those birds. The presence of dye in eggs can be detected through the shell, and different patterns of rings can be distinguished by boiling and sectioning eggs. Application of the method to other species and other circumstances is considered.     

Tests of randomness for pseudorandom number generators

This study examined the “randomness” of the numbers generated by the VIC-20 computer. Using eight standard tests, it was determined that the numbers provided by the VIC-20 are adequately random for practical purposes. The tests are applicable to other computer systems and provide a general means for evaluating random-number generators.     

A low-stress restraint procedure for EEG acquisition in awake rats

A restraint procedure was developed to reduce movement-related artifacts during the acquisition of EEG data from unanesthetized, unparalyzed rats. It combines the low-stress properties of a cloth restraint bag with the improved immobility of a rigid restraint device. The spontaneous behavior of the rat facilitates both the induction of and the subsequent release from restraint.