Cerebral blood flow in normal and abnormal sleep and dreaming

Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming.     

Self-regulation of stimulation for ADD-H children during reading and vigilance task performance

The present study examines the hypothesis that motor responses added into rote tasks would modulate the sensation-seeking activity and impulsive errors of hyperactive (ADD-H) children. To this purpose 22 ADD-H and 25 comparison children were administered two repetitive tasks (word decoding and an auditory vigilance task) under both an active response and a passive response condition. Findings were that the impulsive errors, talking/noise-making, and activity of ADD-H children was normalized (i.e., did not differ from comparison children) only in the high stimulation active response conditions. Behavioral improvements for ADD-H children were documented in both tasks in the active condition, but performance gains were found only in the vigilance task. The findings supported predictions derived from the optimal stimulation theory that the excessive activity and attraction to novel stimuli of ADD-H children can be channeled into appropriate instrumental motor and attention responses.We thank Anne Dwyer for her help with data collection, and Phyllis Kikendall, Sylvia Kottler, Joe Boggs, and Cheryl Wieczorek for their assistance at various stages of this project. We are also most grateful to Martha Eger and to the teachers, Sally Schnieder and Denise Oliver, of West Central Joint Special Services, to Pat Welch of the Catholic Social Services, and to the teachers of St. Ann's School and St. Philip Neri School for their cooperation with this research.     

Completeness and conservative extension results for some boolean relevant logics

This paper presents completeness and conservative extension results for the boolean extensions of the relevant logic T of Ticket Entailment, and for the contractionless relevant logics TW and RW. Some surprising results are shown for adding the sentential constant t to these boolean relevant logics; specifically, the boolean extensions with t are conservative of the boolean extensions without t, but not of the original logics with t. The special treatment required for the semantic normality of T is also shown along the way.     

Detection and identification thresholds for consonant-vowel syllables

Detection and identification thresholds were obtained for 6- and 10-year-old normal children and normal adults using five-formant synthesized consonant-vowel ([baHdflrfea]) stimuli. Sixyear-old children were found to have poorer detection than adults, just as they do for pure tones. For the identification task, the slopes of the performance-intensity functions were more shallow for 6-year-old children than for 10-year-olds and adults. Consequently, compared with 10-yearolds and adults, 6-year-old listeners require a greater increase in stimulus intensity above detection threshold to identify these stimuli at a high performance level. The influence of acoustic characteristics of the stimuli on all listeners is also discussed.     

Functions of graphemic and phonemic codes in visual word-recognition

Previous investigators have argued that printed words are recognized directly from visual representations and/or phonological representations obtained through phonemic recoding. The present research tested these hypotheses by manipulating graphemic and phonemic relations within various pairs of letter strings. Ss in two experiments classified the pairs as words or nonwords. Reaction times and error rates were relatively small for word pairs (e.g., BRIBE-TRIBE) that were both graphemically, and phonemically similar. Graphemic similarity alone inhibited performance on other word pairs (e.g., COUCH-TOUCH). These and other results suggest that phonological representations play a significant role in visual word recognition and that there is a dependence between successive phonemic-encoding operations. An encoding-bias model is proposed to explain the data.     

Kommunikationsstruktur und Gruppenleistung

Zusammenfassung Vierergruppen von Vpn arbeiteten in Kommunikationsnetzen, in denen es infolge des Fehlens einer (direkten oder indirekten) Wechselseitigkeit gewisser Verbindungen einigen Vpn — nämlich denjenigen, die ganz bestimmte (ungünstige) Positionen innerhalb des Netzes einnahmen — verwehrt war, die Lösung eines Problems durch Austausch von Informationen zu finden. Den Vpn-Gruppen wurde diese Eigenschaft der Kommunikationssysteme bei Beginn der Versuche nicht mitgeteilt. In einer derartigen Lage suchen jene Vpn den Grund für den unbefriedigenden Informationsaustausch (zumindest zunächst) nicht in der Struktur des Kommunikationsnetzes, sondern unterstellen den anderen Gruppenmitgliedern mangelnde Loyalität oder/und mangelndes Verständnis. Die Folge sind starke affektive Spannungen, die zur Verschlechterung der Kooperation und zur Verringerung der Gruppenleistung führen. Die kognitive Seite des Erlebens der Vpn wurde u. a. mit Hilfe der Begriffe phänomenale Variabilität und phänomenale Konstanz näher analysiert.     

Naturwissenschaft und Logik

Ohne Zusammenfassung     

Temporal properties of human information processing: Tests of discrete versus continuous models

Cognitive psychologists have characterized the temporal properties of human information processing in terms of discrete and continuous models. Discrete models postulate that component mental processes transmit a finite number of intermittent outputs (quanta) of information over time, whereas continuous models postulate that information is transmitted in a gradual fashion. These postulates may be tested by using an adaptive response-priming procedure and analysis of reaction-time mixture distributions. Three experiments based on this procedure and analysis are reported. The experiments involved varying the temporal interval between the onsets of a prime stimulus and a subsequent test stimulus to which a response had to be made. Reaction time was measured as a function of the duration of the priming interval and the type of prime stimulus. Discrete models predict that manipulations of the priming interval should yield a family of reaction-time mixture distributions formed from a finite number of underlying basis distributions, corresponding to distinct preparatory states. Continuous models make a different prediction. Goodness-of-fit tests between these predictions and the data supported either the discrete or the continuous models, depending on the nature of the stimuli and responses being used. When there were only two alternative responses and the stimulus-response mapping was a compatible one, discrete models with two or three states of preparation fit the results best. For larger response sets with an incompatible stimulus-response mapping, a continuous model fit some of the data better. These results are relevant to the interpretation of reaction-time data in a variety of contexts and to the analysis of speed-accuracy trade-offs in mental processes.