Are insomniacs sleepy during the day? A pupillometric assessment.

A biodevelopmental model of insomnia is articulated specifying coordinated nighttime (disturbed sleep pattern) and daytime (no excessive daytime sleepiness) characteristics defining an insomnoid classification in at-risk groups: short sleepers and older adults. Pupillometry is proposed as a useful means of discriminating degree of daytime sleepiness to aid in the differential diagnosis of insomnia and insomnoid states, and the present study tested the discriminative validity of this approach. Noninsomniac (n = 34) and insomniac (n = 29) college students submitted to four 10 min pupillometry sessions tracking daytime sleepiness from morning arising to bedtime. Pupil diameter proved to be an able discriminator of these two groups though substantial overlap of the two distributions was also noted. The results supported the sensitivity of pupillometry in detecting daytime sleepiness, but yielded alternative interpretations. We observed statistical differentiation in insomniac and noninsomniac daytime sleepiness, but substantial, functional overlap between these groups. Assessment and treatment implications arising from the biodevelopmental model were hypothesized.     

Constrained classification: The use of a priori information in cluster analysis

In many classification problems, one often possesses external and/or internal information concerning the objects or units to be analyzed which makes it appropriate to impose constraints on the set of allowable classifications and their characteristics. CONCLUS, or CONstrained CLUStering, is a new methodology devised to perform constrained classification in either an overlapping or nonoverlapping (hierarchical or nonhierarchial) manner. This paper initially reviews the related classification literature. A discussion of the use of constraints in clustering problems is then presented. The CONCLUS model and algorithm are described in detail, as well as their flexibility for use in various applications. Monte Carlo results are presented for two synthetic data sets with appropriate discussion of the resulting implications. An illustration of CONCLUS is presented with respect to a sales territory design problem where the objects classified are various Forbes-500 companies. Finally, the discussion section highlights the main contribution of the paper and offers some areas for future research.We wish to thank C. Mallows and J. D. Carroll for some helpful technical discussion and L. Clark and D. Art for their valuable computer assistance. We also wish to thank H. Pollak, R. Gnanadesikan, and J. Kettenring for their thorough reviews of a previous draft of this paper. Finally, we acknowledge helpful comments of the editor and two anonymous reviewers.     

Vigilance, personality and strength of the nervous system

Numerous attempts have been made to explain the overall level of performance and the change in performance over time in vigilance tasks in terms of the proposed inverted U relationship between performance and ‘arousal’. The present experiment investigated the effects on vigilance performance of the following variables: introversion, neuroticism, time of day, accessory sensory stimulation, ‘signal frequency’ and time on task. Some measures of subjective state and body temperature were also included. The behavioural measures of overall performance revealed interactions involving neuroticism and time of day, and between neuroticism and frequency. This may reflect the operation of response bias factors, though these may be influenced by ‘arousal’. There were also main effects for several of the factors which may have practical significance. There was a significant effect of time on task on all the behavioural measures but no clearcut effects of personality on the vigilance ‘decrement’. It is argued that the latter may not provide the most satisfactory test of the inverted U model and its relationship to personality. However, interactions between noise and time on task for some of the measures may have practical importance. Measures of subjective state showed a fall in the reported level of ‘arousal’ accompanied by a rise in reported ‘stress’ and ‘anxiety’ with time on task. Body temperature was higher after the task than before.     

The Truth about Realism: Natural Realism,Many Worlds,and Global M-Realism

Philosophia - An attempt was made to show how we can plausibly commit to mathematical realism. For the purpose of illustration, a defence of natural realism for arithmetic was developed that draws...     

M. Chirimuuta's Adverbialism about Color

M. Chirimuuta's Outside Color is a rich and lovely book. I enjoyed reading it and benefitted from reflecting on its provocative ideas. I begin by briefly placing the book's principal thesis in its historical context, and I go on to reflect on two objections that might be lodged against this thesis.     

Aphasia type and aging in Hindi-speaking stroke patients

In this study, the clinical profile of Hindi-speaking stroke patients with aphasia from northern India has been investigated. We examined the interactional effect between age and gender with aphasia type in 97 Hindi-speaking right-handed individuals, the majority of them with a confirmed diagnosis of a cerebrovascular accident. The subjects included in the study ranged from 3 weeks to two years post-onset with a diagnosis of a common classical aphasia (Broca's, Wernicke's, anomic, global, conduction, and transcortical) types involving both males and females. Also examined was the interaction between literacy and aphasia type since the subjects had varied exposures to education (total illiteracy to professional/university education). While the data reported here about Hindi-speaking aphasics are relatively in agreement with the age-aphasia type patterns discussed in western countries, nonetheless some differences were also observed. The mean age of Indian patients with aphasia was significantly lower. Also, in addition to some gender and literacy related differences, an outstanding difference was that many clinical symptoms that are known to co-occur with aphasia were not readily reported by subjects with stroke.     

Rapid communication: Global-local processing affects recognition of distractor emotional faces

Recent studies have shown links between happy faces and global, distributed attention as well as sad faces to local, focused attention. Emotions have been shown to affect global-local processing. Given that studies on emotion-cognition interactions have not explored the effect of perceptual processing at different spatial scales on processing stimuli with emotional content, the present study investigated the link between perceptual focus and emotional processing. The study investigated the effects of global-local processing on the recognition of distractor faces with emotional expressions. Participants performed a digit discrimination task with digits at either the global level or the local level presented against a distractor face (happy or sad) as background. The results showed that global processing associated with broad scope of attention facilitates recognition of happy faces, and local processing associated with narrow scope of attention facilitates recognition of sad faces. The novel results of the study provide conclusive evidence for emotion-cognition interactions by demonstrating the effect of perceptual processing on emotional faces. The results along with earlier complementary results on the effect of emotion on global-local processing support a reciprocal relationship between emotional processing and global-local processing. Distractor processing with emotional information also has implications for theories of selective attention.