MANULEX: A grade-level lexical database from French elementary school readers

This article presents MANULEX, a Web-accessible database that provides grade-level word frequency lists of nonlemmatized and lemmatized words (48,886 and 23,812 entries, respectively) computed from the 1.9 million words taken from 54 French elementary school readers. Word frequencies are provided for four levels: first grade (G1), second grade (G2), third to fifth grades (G3-5), and all grades (G1-5). The frequencies were computed following the methods describedby Carroll, Davies, and Richman (1971) and Zeno, Ivenz, Millard, and Duwuri (1995), with four statistics at each level (F, overall word frequency;D, index of dispersion across the selectedreaders;U, estimated frequencyper million words; andSFI, standard frequency index). The database also provides the number of letters in the word and syntactic category information. MANULEX is intended to be a useful tool for studying language development through the selection of stimuli based on precise frequency norms. Researchers in artificial intelligence can also use it as a source of information on natural language processing to simulate written language acquisition in children. Finally, it may serve an educational purpose by providing basic vocabulary lists.     

Alzheimer's disease disrupts arithmetic fact retrieval processes but not arithmetic strategy selection

Three groups of healthy younger adults, healthy older adults, and probable AD patients, performed an addition/number comparison task. They compared 128 couples of additions and numbers (e.g., 4 + 9 15) and had to identify the largest item for each problem by pressing one of two buttons located under each item. Manipulations of problem characteristics (i.e., problem difficulty and splits between correct sums and proposed numbers) enabled us to examine strategy selection and specific arithmetic fact retrieval processes. Results showed that arithmetic facts retrieval processes, which were spared with aging, were impaired in AD patients. However, AD patients were able to switch between strategies across trials according to problem characteristics as well as healthy older adults, and less systematically than healthy younger adults. We discuss implications of these findings for further understanding AD-related differences in arithmetic in particular, and problem solving in general.     

Effects of sleep deprivation on Color-Word, Emotional, and Specific Stroop interference and on self-reported anxiety

The aim of this study was principally to assess the impact of sleep deprivation on interference performance in short Stroop tasks (Color-Word, Emotional, and Specific) and on subjective anxiety. Subjective sleepiness and performance on a psychomotor sustained attention task were also investigated to validate our protocol of sleep deprivation. Twelve healthy young subjects were tested at four-hourly intervals through a 36-h period of wakefulness under a constant routine protocol. Analyses of variance for repeated measurements revealed that self-assessment of sleepiness on a visual analogue scale as well as mean reaction time performance on the sustained attention task, both for the first minute and for 10 min of testing, were worsened by sleep deprivation. Analyses revealed an increase in self-reported anxiety scores on the STAI questionnaire but did not reveal any significant effect after sleep deprivation either on indexes of interference or on accuracy in Stroop tasks. However, analyses showed sensitivity to circadian effect on verbal reaction times in the threat-related (Emotional) and sleep-related (Specific) Stroop tasks. We concluded that 36 h of prolonged wakefulness affect self-reported anxiety and Emotional Stroop task resulting in a cognitive slowing. Moreover, total sleep deprivation does not affect interference control in any of the three short Stroop tasks.     

The discrimination of temporal fine structure in call-like harmonic sounds by birds

Thresholds for discriminating changes in the temporal fine structure of call-like, harmonic sounds were measured in zebra finches (Taeniopygia guttata) and budgerigars (Melopsittacus undulatus). Birds could detect changes in periods as short as 1.225 ms at near 100% accuracy even when spectral and envelope cues were identical, as in time-reversed stimuli. Humans performed poorly on such stimuli, paralleling results from previous studies. Bird thresholds were in the range of those reported in neurophysiological studies of the songbird high vocal center (HVC) to temporally modified conspecific songs. Taken together, these results show that birds can hear differences in temporal fine structure in their natural vocalizations that go beyond human capabilities, but whether these abilities have communicative relevance remains to be seen.     

Decision making and interference in the domestic cat (Felis catus)

Domestic cats (Felis catus) received a task in which an obstacle was introduced at the time they were ready to reach for 1 among 2 or 3 baited targets. The results revealed that when the initially chosen direction (i.e., before the introduction of the obstacle) and the new one were orthogonal, the cats reassessed distance, angular deviation, and visibility once they had turned around the obstacle (Experiments 1, 2, and 3). Then the cats chose a different target than the one that would have been chosen had there been no obstacle. When both the initially chosen and the new direction matched (Experiment 4), the cats kept intact their initial decision. The discussion focuses on the nature of the representational system of the cat. The discussion also emphasizes comparisons with dogs (i.e., cooperative hunters).     

Instrumental learning in hyperdopaminergic mice

In two experiments we investigated the effects of elevated dopaminergic tone on instrumental learning and performance using dopamine transporter knockdown (DAT KD) mice. In Experiment 1, we showed that both DAT KD mice and wild-type controls were similarly sensitive to outcome devaluation induced by sensory specific satiety, indicating normal action-outcome learning in both groups. In Experiment 2, we used a Pavlovian-to-instrumental transfer procedure to assess the potentiation of instrumental responding by Pavlovian conditional stimuli (CS). Although during the Pavlovian training phase the DAT KD mice entered the food magazine more frequently in the absence of the CS, when tested later both groups showed outcome-selective PIT. These results suggest that the elevated dopaminergic tone reduced the selectivity of stimulus control over conditioned behavior, but did not affect instrumental learning.     

Heart rate changes during conditioning-specific reflex modification of the rabbit's (Oryctolagus cuniculus) nictitating membrane response

Conditioning-specific reflex modification (CRM) of the rabbit's nictitating membrane response (NMR) involves changes in responding to an unconditioned stimulus (US) when the US is tested in the absence of the conditioned stimulus. Previous experiments have shown that CRM is a function of the type and intensity of the aversive US used during classical conditioning. As a result, it has been suggested that CRM may be mediated, at least in part, by the aversiveness of the US. Here, we show that by using a moderately intense electrical pulse to the skin as a US, CRM of the rabbit NMR is accompanied by an increase in heart rate. The largest changes in heart rate occur at US intensities that produce the strongest levels of CRM. The heart rate data show that there may be an increased emotional/arousal component to the US that is correlated with CRM and support the use of CRM as a potential model for posttraumatic stress disorder.     

Very young children are insensitive to picture- but not object-orientation

In two experiments on very young children's response to the orientation of pictures and objects, 18-, 24- and 30-month-old children showed no preference for upright pictures over inverted ones. More importantly, we found that children in all three age groups were equally accurate and equally fast at identifying depicted objects regardless of orientation. These studies further established that young children's insensitivity to picture orientation does not extend to objects. These results, in combination with the earlier ones, indicate that only gradually do young children come to share the picture orientation preference of adults and older children and that their adoption of the orientation convention is not based on changes in their ability to process upright and inverted images.     

Sequential combinations of drug and cognitive behavioral therapy for chronic insomnia: an exploratory study

This study explores the efficacy of sequential treatments involving medication and cognitive behavioral treatment (CBT) for primary insomnia. Seventeen participants took part in a multiple baseline design and were assigned to: (a) medication for 5 weeks, followed by combined medication plus CBT for 5 weeks; (b) combined treatment for 5 weeks, followed by CBT alone; or (c) CBT alone. Each treatment sequence produced significant sleep improvements, but at different points in time. For the first sequence, most of the sleep improvement was obtained after the introduction of CBT, while for the other sequence and CBT alone, improvement appeared during the first weeks. These results suggest that sleep improvement seems affected by the way treatments are combined. Also, a sequence beginning with a combined treatment followed by CBT alone seems to produce the best outcome. Additional research should be conducted with larger samples to determine the most effective sequence.