Spatial compatibility of signal-response position in pointing

Two experiments are reported in which, by means of a pointing task, we studied the stimulus-position effect, i.e. the inverted U-shape form of the reaction-time function in relation to stimulus position in tasks in which stimuli and/or responses are arranged in a horizontal array. The response consisted of aiming the index finger from a central starting point at a target area on a screen. Reaction time was the main dependent variable. The spatial relation between the position of the imperative signal and the position of the response was manipulated by varying the spatial S-R compatibility and physical distance that separated the positions of stimulus and response. The stimulus-position effect was shown to depend on the compatibility of the S-R relation (Exp. 1). In Exp. 2 it was found that the modulation of the stimulus-position effect by spatial compatibility disappeared completely when the distance between the positions of stimulus and response was reduced. None of the experiments revealed that the stimulus position effect depended on signal discriminability, which renders an interpretation of this effect in terms of perceptual processes unlikely. We argue that the attentional model of spatial coding provides the most reasonable explanation of the obtained reaction-time patterns.     

The Relative Importance of Anticipated Test Format and Anticipated Test Difficulty on Performance

In this investigation, the relative importance of the effects of anticipated test format and anticipated test difficulty on performance was examined by simultaneously manipulating both. Experiments 1 and 2 showed that test performance was affected more by anticipated test format than by anticipated test difficulty. This suggests that the superior performance of subjects who had anticipated a recall test versus those who had anticipated a recognition test, reported here and in previous studies, is more likely to be due to anticipating a recall format than to anticipating a more difficult test. Experiment 2 showed that subjects who had anticipated a recall test studied longer than subjects who had anticipated a recognition test, even when recall tests were less difficult than recognition tests. One explanation for this finding is that subjects inaccurately monitor the relative difficulty of tests across test formats. Subjects rated recall items as more difficult than recognition items, even when recall items are actually less difficult (Experiment 3). These findings suggest that a priori metacognitive knowledge may reduce the accuracy of on-line metacognitive monitoring.     

TWO ISSUES IN AUDITORY COGNITION:

Abstract— The study of auditory and music cognition provides opportunities to explore general cognitive mechanisms in a specific, highly structured domain We discuss two problems with implications for other domains of perception the self-organization of perceptual categories and invariant pattern recognition The perceptual category we consider is the octave We show how general principles of self-organization operating on a cochlear spectral representation can vield octave categories The example of invariant pattern recognition we consider is the recognition of invariant frequency patterns transformed to different absolute frequencies We suggest a system that uses pitch or musical key to map tones into a pitch-invariant format.     

A Comparison of the Validity of Handwriting Analysis With That of the Cattell 16PF

Few British organizations utilize handwriting analysis for personality assessment, but in some European countries handwriting analysis is extremely popular. Research has examined the reliability and validity of both methods of assessment, but few studies have directly compared the two. In this study, the personality of 120 subjects was assessed by the Cattell 16PF and by handwriting analysis. Each subject was presented with five handwriting analysis textual reports and five personality textual reports (one of each being their own) and asked to rank order each set in terms of perceived accuracy. The same ranking process was undertaken by each respondent's social partner. The results demonstrated that handwriting reports were ranked at a chance level by Self and by Other and that personality reports were ranked at a well above chance level by Self and by Other. Self-rankings were more accurate than Other-rankings.     

A comparison of multiple versus single examples of the correct stimulus on task acquisition and generalization by persons with developmental disabilities

In teaching discriminations to persons with retardation, we often presume we will improve acquisition and generalization if we use multiple examples of boththe correct and incorrect stimuli. Two experiments were conducted to test this hypothesis. In the first experiment, 7 persons with moderate retardation learned to discriminate between functional words under two conditions. In one condition, Multiple Example of S- Only,1 example of the correct stimulus (S+) and 10 examples of the incorrect stimulus (S-) were used during acquisition. In the other condition, Multiple Examples of S+ and S-,10 examples of the S+ and 10 examples of the S- were used. Results showed that the condition which presented only a single example of S+ was superior 16 times and inferior 4 times during acquisition, generalization, and maintenance. A second experiment was conducted to (a) replicate the methodology and procedures in Experiment 1 with different participants, (b) determine whether the results were replicable, and (c) obtain efficiency data. Results replicated the findings of the first experiment. The condition which presented only a single example of S+ was superior on measures of (a) trials to criterion, (b) percent correct during acquisition, and (c) minutes to criterion. On measures of generalization, the two conditions were relatively equal. Thus, the condition which presented only a single example of the correct stimulus was more efficient and was just as effective in generalization as the condition which presented multiple examples of both the S+ and S-. These surprising results were discussed in terms of stimulus control, why students performed just as well during generalization when only one example of the S+ was used, why acquisition was also poorer for this condition, and how future studies might address these points.     

Event-related brain potentials elicited by rhyming and non-rhyming pictures differentiate subgroups of reading disabled adolescents

Event-related brain potentials were recorded while disabled adolescent subjects read and judged whether two sequentially presented pictures had names that rhymed. Subjects with relatively good phonetic skills displayed an N400 priming effect, i.e., a significant reduction in the amplitude of the negative peak, occurring approximately 400 msec post-stimulus, for pictures with names that rhymed with preceding pictures as compared with pictures that had names that did not rhyme with the prime. No such effect was evident for subjects with relatively poor phonetic skills. This lack of an N400 priming effect provides evidence for a reduction in neural capacity and/or activation during phonological processing in the subjects with poor phonological skills. Demonstrating the N400 priming effect to be stronger in one group of reading disabled subjects, compared to another, supports the position that specific subtypes of reading disability exist. In addition to the stronger N400 priming effect, the phonetically stronger group also exhibited an enhanced negativity, from 700 to 1,000 msec after target stimulus onset, compared to phonetically inferior subjects. This finding replicates earlier work and possibly reflects a higher level of confidence in the group with better phonetic skills.     

What shall we do with Norman? An experiment in communal discernment.

We were a group of Christian friends searching for affirmations that lay at the heart of our faith and reached to the limits of our existence and moral authority. As we have reflected on our role in deciding whether and to what extent we could assist in allowing our terminally ill friend, seventy-nine-year-old, Norman to die, we were deeply troubled by the moral ambiguity of our involvement. Through a careful process of authority through communal discernment, our responsibility for Norman became clear: we were to assist him in living the life he embraced in baptism -- a life which included a destiny that was conformed to the crucified and risen one. That was not the destiny we chose for Norman; it was the destiny he owned. We recognized with Norman that our lives are not our own to be guided by autonomy and liberty, but rather to be lived for the glory of Jesus the Christ.     

Fourier analysis of movement patterns in pigeons

Fourier analysis describes the amount of variation in a time series by partitioning it into sinusoids of different amplitudes and wavelengths and quantifying the extent to which these waves are synchronized. The importance of a given wave is represented by its contribution to the explained variance of the time series. To illustrate its potential application to the study of movement, Fourier analysis was used to quantify the movement patterns of 2 pigeons on a variable-interval (VI) and a variable-time (VT) schedule of reinforcement. For comparison, the movements of 2 pigeons that did not receive reinforcement were similarly analyzed. Characteristic frequencies were higher during VI than during VT, and relatively low during nonreinforcement. We concluded that Fourier analysis can be used to represent movement patterns compactly, study their periodicity, stereotypy, and resonance, and assist in computer simulations and models of movement.