Adolescent television viewing and belief in vampires

A total of 1133 13–15‐year‐old pupils in six secondary schools in South Wales were invited to complete questions concerning vampire belief and amount of television watching. The data demonstrate that belief in vampires was positively associated with higher levels of television watching.     

Age‐related changes in transient and oscillatory brain responses to auditory stimulation during early adolescence

Maturational changes in the capacity to process quickly the temporal envelope of sound have been linked to language abilities in typically developing individuals. As part of a longitudinal study of brain maturation and cognitive development during adolescence, we employed dense‐array EEG and spatiotemporal source analysis to characterize maturational changes in the timing of brain responses to temporal variations in sound. We found significant changes in the brain responses compared longitudinally at two time points in early adolescence, namely 10 years (65 subjects) and 11.5 years (60 of the 65 subjects), as well as large differences between adults, studied with the same protocol ( Poulsen, Picton & Paus, 2007 ), and the children at 10 and 11.5 years of age. The transient auditory evoked potential to tone onset showed decreases in the latency of vertex and T‐complex components, and a highly significant increase in the amplitude of the N1 wave with increasing age. The auditory steady state response to a 40‐Hz frequency‐modulated tone increased in amplitude with increasing age. The peak frequency of the envelope‐following response to sweeps of amplitude‐modulated white noise also increased significantly with increasing age. These results indicate persistent maturation of the cortical mechanisms for auditory processing from childhood into middle adulthood.     

Electrophysiological manifestations of typicality judgment

Ten male subjects participated in an event-related potential study of typicality judgment of words that were of either high or low frequency of usage. The amplitude of a negative wave with an average peak latency of 490 msec (N400) correlated with the goodness-of-fit of a word to a particular category independent of frequency, with poor examples of the category evoking a significantly more negative waveform. The relative insensitivity of the N400 to word frequency suggests that the N400 reflects some postlexical evaluation rather than lexical access.     

Locus of the effect of a surprising reinforcer in the attenuation of blocking

Previous experiments on conditioned suppression in rats have shown that prior conditioning to one element of a compound conditioned stimulus paired with shock may block or prevent conditioning to the other element. Reliable conditioning may, however, occur to the added element (blocking may be attenuated), if a surprising second shock is added shortly after each compound trial. Experiment I confirmed this finding, and further showed that blocking was attenuated only when the second shock occurred 10 s after the compound trial, not when it occurred 100 s later. Experiment II showed that the surprising omission of an expected second shock 10 s after each compound trial would also attenuate blocking, thus implying that the surprising event does not itself act to reinforce conditioning to the added element, but rather permits the unconditioned stimulus (the first shock) to play its normal role as an effective reinforcer. This conclusion was confirmed by Experiment III, which showed that a surprising second shock does not produce any increase in conditioning to the added element on the trial on which it occurs; rather it serves to ensure adequate conditioning to that element on a subsequent compound trial. The implication is that the surprising event acts proactively to prevent subjects learning to ignore an otherwise redundant stimulus.     

Perceptual closure and object identification: electrophysiological responses to incomplete pictures.

Event-related potentials were recorded during the naming of pictures of concrete objects. The pictures were presented at three levels of completeness: 10, 30, and 60%. The ERP waveforms were evaluated according to the level of picture completeness and the correctness of naming. A negative wave in the latency range of 250-550 ms was significantly more negative when the pictures were more incomplete, regardless of the correctness of response. This N400 wave is proposed as being related to hypotheses about the identity of the object. A late positive wave in the latency range of 550-650 ms followed the negativity, but only when the response was correct. This may reflect the subject's certainty about the perceptual analysis, a verification of the identity of the object. A slow parietal negativity lasting up to 2 sec was largest for the least complete picture. This therefore varied with the perceptual difficulty.     

Bottom-up and top-down influences on auditory scene analysis: evidence from event-related brain potentials

The physiological processes underlying the segregation of concurrent sounds were investigated through the use of event-related brain potentials. The stimuli were complex sounds containing multiple harmonics, one of which could be mistuned so that it was no longer an integer multiple of the fundamental. Perception of concurrent auditory objects increased with degree of mistuning and was accompanied by negative and positive waves that peaked at 180 and 400 ms poststimulus, respectively. The negative wave, referred to as object-related negativity, was present during passive listening, but the positive wave was not. These findings indicate bottom-up and top-down influences during auditory scene analysis. Brain electrical source analyses showed that distinguishing simultaneous auditory objects involved a widely distributed neural network that included auditory cortices, the medial temporal lobe, and posterior association cortices.     

Brain oscillations during semantic evaluation of speech

Changes in oscillatory brain activity have been related to perceptual and cognitive processes such as selective attention and memory matching. Here we examined brain oscillations, measured with electroencephalography (EEG), during a semantic speech processing task that required both lexically mediated memory matching and selective attention. Participants listened to nouns spoken in male and female voices, and detected an animate target (p = 20%) in a train of inanimate standards or vice versa. For a control task, subjects listened to the same words and detected a target male voice in standards of a female voice or vice versa. The standard trials of the semantic task showed enhanced upper beta (25–30 Hz) and gamma band (GBA, 30–60 Hz) activity compared to the voice task. Upper beta and GBA enhancement was accompanied by a suppression of alpha (8–12 Hz) and lower to mid beta (13–20 Hz) activity mainly localized to posterior electrodes. Enhancement of phase-locked theta activity peaking near 275 ms also occurred over the midline electrodes. Theta, upper beta, and gamma band enhancement may reflect lexically mediated template matching in auditory memory, whereas the alpha and beta suppression likely indicate increased attentional processes and memory demands.