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Chance Level (chance + level)
Selected AbstractsDiversity of the Vocal Signals of Concave-Eared Torrent Frogs (Odorrana tormota): Evidence for Individual SignaturesETHOLOGY, Issue 11 2009Albert S. Feng Male concave-eared torrent frogs (Odorrana tormota) have an unusually large call repertoire and have been shown to communicate ultrasonically. We investigated the individual specificity of male advertisement calls in order to explore the acoustic bases of individual recognition, which was demonstrated in an accompanying study. Vocalizations of 15 marked males were recorded in the field. A quantitative analysis of the signals revealed eight basic call-types. Two of them (the single- and multi-note long-calls) were investigated in more detail. Long-calls were characterized by pronounced and varying frequency modulation patterns, and abundant occurrence of nonlinear phenomena (NLP), i.e., frequency jumps, subharmonics, biphonations and deterministic chaos. The occurrence of NLP was predictable from the contour of the fundamental frequency in the harmonic segment preceding the onset of the NLP, and this prediction showed individual-specific patterns. Fifteen acoustic variables of the long calls were measured, all of which were significantly different among individuals, except biphonic segment duration. Discriminant function analysis (DFA) showed that 54.6% of the calls could be correctly assigned to individual frogs. The correct classification was above chance level, suggesting that individual specificity of calls underlie the ability of males to behaviorally discriminate the vocal signals of their neighbors from those of strangers, a remarkable feat for a frog species with a diverse vocal repertoire. The DFA classification results were lower than those for other anurans, however. We hypothesize that there is a tradeoff between an increase in the fundamental frequency of vocalizations to avoid masking by low-frequency ambient background noise, and a decrease in individual-specific vocal tract information extractable from the signal. [source] Rapid categorization of achromatic natural scenes: how robust at very low contrasts?EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2005Marc J.-M. Abstract The human visual system is remarkably good at categorizing objects even in challenging visual conditions. Here we specifically assessed the robustness of the visual system in the face of large contrast variations in a high-level categorization task using natural images. Human subjects performed a go/no-go animal/nonanimal categorization task with briefly flashed grey level images. Performance was analysed for a large range of contrast conditions randomly presented to the subjects and varying from normal to 3% of initial contrast. Accuracy was very robust and subjects were performing well above chance level (, 70% correct) with only 10,12% of initial contrast. Accuracy decreased with contrast reduction but reached chance level only in the most extreme condition (3% of initial contrast). Conversely, the maximal increase in mean reaction time was ,,60 ms (at 8% of initial contrast); it then remained stable with further contrast reductions. Associated ERPs recorded on correct target and distractor trials showed a clear differential effect whose amplitude and peak latency were correlated respectively with task accuracy and mean reaction times. These data show the strong robustness of the visual system in object categorization at very low contrast. They suggest that magnocellular information could play a role in ventral stream visual functions such as object recognition. Performance may rely on early object representations which lack the details provided subsequently by the parvocellular system but contain enough information to reach decision in the categorization task. [source] Muscarinic receptor blockade in ventral hippocampus and prelimbic cortex impairs memory for socially transmitted food preferenceHIPPOCAMPUS, Issue 5 2009Anna Carballo-Márquez Abstract Acetylcholine is involved in learning and memory and, particularly, in olfactory tasks, but reports on its specific role in consolidation processes are somewhat controversial. The present experiment sought to determine the effects of blocking muscarinic cholinergic receptors in the ventral hippocampus (vHPC) and the prelimbic cortex (PLC) on the consolidation of social transmission of food preference, an odor-guided relational task that depends on such brain areas. Adult male Wistar rats were bilaterally infused with scopolamine (20 ,g/site) immediately after social training and showed impairment, relative to vehicle-injected controls, in the expression of the task measured 24 h after learning. Results indicated that scopolamine in the PLC completely abolished memory, suggesting that muscarinic transmission in this cortical region is crucial for consolidation of recent socially acquired information. Muscarinic receptors in the vHPC contribute in some way to task consolidation, as the rats injected with scopolamine in the vHPC showed significantly lower trained food preference than control rats, but higher than both chance level and that of the PLC-injected rats. Behavioral measures such as social interaction, motivation to eat, neophobia, or exploration did not differ between rats infused with scopolamine or vehicle. Such data suggest a possible differential role of muscarinic receptors in the PLC and the vHPC in the initial consolidation of a naturalistic form of nonspatial relational memory. © 2008 Wiley-Liss, Inc. [source] Better Processing of Consonantal Over Vocalic Information in Word Learning at 16 Months of AgeINFANCY, Issue 4 2009Mélanie Havy Previous research using the name-based categorization task has shown that 20-month-old infants can simultaneously learn 2 words that only differ by 1 consonantal feature but fail to do so when the words only differ by 1 vocalic feature. This asymmetry was taken as evidence for the proposal that consonants are more important than vowels at the lexical level. This study explores this consonant-vowel asymmetry in 16-month-old infants, using an interactive word learning task. It shows that the pattern of the 16-month-olds is the same as that of the 20-month-olds. Infants succeeded with 1-feature consonantal contrasts (either place or voicing) but were at chance level with 1-feature vocalic contrasts (either place or height). These results thus contribute to a growing body of evidence establishing, from early infancy to adulthood, that consonants and vowels have different roles in lexical acquisition and processing. [source] Evaluation of the NITV CVSAJOURNAL OF FORENSIC SCIENCES, Issue 1 2008Harry Hollien Ph.D. Abstract:, The purpose of this study was to evaluate a commonly used voice stress analyzer, the National Institute of Truth Verification's (NITV) Computer Voice Stress Analyzer (CVSA), using a speech database containing materials recorded (i) in the laboratory, while highly controlled deceptive and shock-induced stress levels were systematically varied, and (ii) during a field procedure. Subjects were 24 each males/females (age range 18,63 years) drawn from a representative population. All held strong views on an issue and were required to make sharply derogatory statements about it. The CVSA system was then evaluated in a double-blind study using three sets of examiners: (i) two UF scientists trained/certified by NITV in CVSA operation, (ii) three experienced NITV operators provided by the manufacturer and (iii) five experimental phoneticians. The results showed that the "true positive" (or hit) rates for all examiners ranged from chance to somewhat higher levels (c. 50,65%) for all conditions and types of materials (e.g., stress vs. unstressed, truth vs. deception). However, the false-positive rate was just as high , often higher. Sensitivity statistics demonstrated that the CVSA system operated at about chance level. [source] Clinical interest: a study of the influence on general practitioners' prescribing,PHARMACOEPIDEMIOLOGY AND DRUG SAFETY, Issue 4 2007Dorte Gilså Hansen MD Abstract Purpose To analyse the association between general practitioners' clinical interest and prescribing rates in four clinical areas: dyspepsia, depression, headache and diabetes. Methods Data concerning general practitioners' prescribing during 2004 were retrieved from a pharmacy database and linked with data from a physician questionnaire and the National Health Insurance Register. To counterbalance differences in practice populations all 1-year prevalences of prescribing were standardised according to age and gender. Participants were asked ,To what extent do you find the following areas interesting from a professional point-of- view?' Four rating categories were used. The association between clinical interest and standardised prescribing rates was investigated using logistic regression, the Kruskal-Wallis test and a trend test. Results A total of 68 (72%) single-handed general practitioners representative of the total group completed the questionnaire. We observed a two-fold ratio between the 90% and the 10% percentiles of the 1-year prevalences of antisecretory drugs, antidepressants, migraine drugs as well as anti-diabetics. The variation in prescribing of antidepressant and antisecretory drugs was far above chance level. No significant association with clinical interest could, however, be observed for any of the four clinical areas. Conclusion General practitioners' prescribing of the four classes of medical drugs varied considerably. However, only part of this variation was based on chance. This study did not confirm our hypothesis that general practitioners' level of clinical interest in one area corresponds with their prescribing of drugs used within that area. Copyright © 2007 John Wiley & Sons, Ltd. [source] Research Review: What is the association between the social-communication element of autism and repetitive interests, behaviours and activities?THE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 8 2008William P.L. Mandy Autism is currently conceptualised as a unitary disorder, in which social-communication impairments are found alongside repetitive interests, behaviours and activities (RIBAs). This relies upon the validity of the assumption that social-communication impairments and RIBAs co-occur at an above chance level as a result of sharing underlying causes. In the current review it is argued that the evidence for this assumption is scarce: the very great majority of RIBA research has not been intended for or suited to its examination. In fact only three studies are fit to address directly the question of the relationship between social-communication impairment and RIBAs, and these contradict each other. In consequence, further relevant evidence was sought in the behavioural and genetic literature. This approach suggested that the correlation between social-communication impairments and RIBAs has been exaggerated in the current consensus about the autism syndrome, and that these aspects of autism may well share largely independent underlying causes. Some clinical and research implications are discussed. [source] Discrimination of temporal synchrony in intermodal events by children with autism and children with developmental disabilities without autismTHE JOURNAL OF CHILD PSYCHOLOGY AND PSYCHIATRY AND ALLIED DISCIPLINES, Issue 1 2006James M. Bebko Background:, This project examined the intermodal perception of temporal synchrony in 16 young children (ages 4 to 6 years) with autism compared to a group of children without impairments matched on adaptive age, and a group of children with other developmental disabilities matched on chronological and adaptive age. Method:, A preferential looking paradigm was used, where participants viewed non-linguistic, simple linguistic or complex linguistic events on two screens displaying identical video tracks, but one offset from the other by 3 seconds, and with the single audio track matched to only one of the displays. Results:, As predicted, both comparison groups demonstrated significant non-random preferential looking to violations of temporal synchrony with linguistic and non-linguistic stimuli. However, the group with autism showed an impaired, chance level of responding, except when presented with non-linguistic stimuli. Conclusions:, Several explanations are offered for this apparently autism-specific, language-specific pattern of responding to temporal synchrony, and potential developmental sequelae are discussed. [source] Bilateral Bone-Anchored Hearing Aids (BAHAs): An Audiometric Evaluation,THE LARYNGOSCOPE, Issue 1 2004Claudia Priwin MD Abstract Objectives Since the technique to implant bone-anchored hearing aids (BAHAs) with the use of osseointegrated implants was developed in 1977, more than 15,000 patients have been fitted with BAHAs worldwide. Although the majority have bilateral hearing loss, they are primarily fitted unilaterally. The main objective of this study was to reveal benefits and drawbacks of bilateral fitting of BAHAs in patients with symmetric or slight asymmetric bone-conduction thresholds. The possible effects were divided into three categories: hearing thresholds, directional hearing, and binaural hearing. Study Design Prospective study of 12 patients with bilateral BAHAs. Methods Baseline audiometry, directional hearing, speech reception thresholds in quiet and in noise, and binaural masking level difference were tested when BAHAs were fitted unilaterally and bilaterally. Results Eleven of the 12 patients used bilateral BAHAs on a daily basis. Tests performed in the study show a significant improvement in sound localization with bilateral BAHAs; the results with unilateral fitting were close to the chance level. Furthermore, with bilateral application, the improvement of the speech reception threshold in quiet was 5.4 dB. An improvement with bilateral fitting was also found for speech reception in noise. Conclusions Overall, the results with bilateral fitted BAHAs were better than with unilaterally fitted BAHA; the benefit is not only caused simply by bilateral stimulation but also, to some extent, by binaural hearing. Bilateral BAHAs should be considered for patients with bilateral hearing loss otherwise suitable for BAHAs. [source] Skulking around the dinosaur: Eliciting cues to children's deception via strategic disclosure of evidenceAPPLIED COGNITIVE PSYCHOLOGY, Issue 7 2010Franziska Clemens Research has shown that cues to deception are more salient as an effect of strategic use of evidence (SUE) during interviews. This study examined the feasibility of the SUE-technique for eliciting cues to children's deception. Experiment 1 investigated verbal cues to deception as a function of early vs. late disclosure of evidence. Eighty-four children (12,14 years) either guilty or innocent of a mock crime were interviewed. As predicted, deceptive statements were significantly more inconsistent with the evidence than truthful statements, and this was more pronounced as a function of late compared to early disclosure of evidence. In Experiment 2, adult observers (N,=,168) made veracity assessments of the videotaped statements. Observers in the late disclosure condition achieved an accuracy rate higher than chance (63.1%), whereas accuracy rates in the early disclosure condition were at chance level (56%). Accuracy rates were significantly higher for truthful (70.2%), than deceptive statements (48.8%). Copyright © 2009 John Wiley & Sons, Ltd. [source] Convergence between physiological, facial and verbal self-report measures of affective empathy in childrenINFANT AND CHILD DEVELOPMENT, Issue 3 2007Xenia Anastassiou-Hadjicharalambous Abstract The present study investigated the degree of convergence between three different measures of vicarious affective responsiveness (affective empathy),verbal self-report, facial expression and change in heart rate,in typically developing children (N=29, aged 8,10 years), when presented with an emotionally evocative film. Although convergence between physiological and verbal measures was only at chance levels, convergence between facial and physiological measures, and between facial and verbal measures was statistically significant, but low (,=0.30 and 0.22, respectively, p<0.01). These findings have important implications for the assessment of empathy in children and indicate that generalization of results across methods should be undertaken with caution. Copyright © 2007 John Wiley & Sons, Ltd. [source] Captive cotton-top tamarins' (Saguinus oedipus oedipus) use of landmarks to localize hidden food itemsAMERICAN JOURNAL OF PRIMATOLOGY, Issue 4 2009Francine L. Dolins Abstract Seventeen captive cotton-top tamarins (Saguinus oedipus oedipus) were individually tested on their use of spatial relationships between landmarks to locate multiple hidden food items. In two experiments, the tamarins were presented with a spatial-foraging task in which positions of hidden food rewards were fixed in relation to an array of visual cues. In Experiment 1, the cues+hidden food configuration was rotated 90° and the tamarins were successful in locating the food items significantly above chance levels (P<0.01). In Experiment 2 the cues+hidden food configuration was translated (up, down or sideways) from the previously learned configuration, and the monkeys successfully localized the hidden food items (P<0.001). Results indicate that the tamarins relied on the spatial relationship between the multiple landmarks to locate hidden food items rather than on an associative or beacon strategy. The results of these experiments support the contention that when contextually appropriate these captive New World monkeys have the capacity to rely on the spatial relationship or positions of several cues as an array to localize points in their environment. Am. J. Primatol. 71:316,323, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||||||||