Biomedical subjects

Stefan Berti

Publications and source records attributed to Stefan Berti.

11 recordsLinked to original sources

PubMed2006

The development of involuntary and voluntary attention from childhood to adulthood: a combined behavioral and event-related potential study.

OBJECTIVE: This study investigated auditory involuntary and voluntary attention in children aged 6-8, 10-12 and young adults. The strength of distracting stimuli (20% and 5% pitch changes) and the amount of allocation of attention were varied. METHODS: In an auditory distraction paradigm event-related potentials (ERPs) and behavioral data were measured from subjects either performing a sound duration discrimination task or watching a silent video. RESULTS: Pitch changed sounds caused prolonged reaction times and decreased hit rates in all age groups. Larger distractors (20%) caused stronger distraction in children, but not in adults. The amplitudes of mismatch negativity (MMN), P3a, and reorienting negativity (RON) were modulated by age and by voluntary attention. P3a was additionally affected by distractor strength. Maturational changes were also observed in the amplitudes of P1 (decreasing with age) and N1 (increasing with age). P2-modulation by voluntary attention was opposite in young children and adults. CONCLUSIONS: Results suggest quantitative and qualitative changes in auditory voluntary and involuntary attention and distraction during development. The processing steps involved in distraction (pre-attentive change detection, attention switch, reorienting) are functional in children aged 6-8 but reveal characteristic differences to those of young adults. In general, distractibility as indicated by behavioral and ERP measures decreases from childhood to adulthood. SIGNIFICANCE: Behavioral and ERP markers for different processing stages involved in voluntary and involuntary attention reveal characteristic developmental changes from childhood to young adulthood.

Acoustic Stimulation↗

PubMed2006

Visual distraction: a behavioral and event-related brain potential study in humans.

Recent studies reported that the detection of changes in the visual stimulation results in distraction of cognitive processing. From event-related brain potentials it was argued that distraction is triggered by the automatic detection of deviants. We tested whether distraction effects are confined to the detection of a deviation or can be triggered by changes per se, namely by rare stimuli that were not deviant with respect to the stimulation. The results obtained comparable early event-related brain potential effects for rare and deviant stimuli, suggesting an automatic detection of these changes. In contrast, behavioral distraction and attention-related event-related brain potential components were confined to deviant stimuli. This finding suggests that deviancy from a given standard adds a genuine contribution to distraction.

Adult↗

PubMed2006

Different interference effects in musicians and a control group.

In the present study musicians and normal control subjects performed an S1-S2 pitch comparison task, which included the presentation of intervening tones during the retention interval. The time for encoding and storing the pitch of S1 was varied between 200 and 1,500 ms by changing the pause between the S1 offset and the onset of the intervening tones. Although musicians outperformed the control group with longer pauses after the S1 offset, this advantage was relatively small with shorter pauses. These results suggest that the advantage of musicians in storing auditory information is not solely due to their superior encoding of information but also to improved working memory operations.

Adolescent↗

PubMed2005

Examining task-dependencies of different attentional processes as reflected in the P3a and reorienting negativity components of the human event-related brain potential.

Unexpected changes in task-irrelevant auditory stimuli are capable to distract processing of task-relevant visual information. This effect is accompanied by the elicitation of event-related potential (ERP) components associated with attentional orientation, i.e. P3a and reorienting negativity (RON). In the present study we varied the demands of a visual task in order to test whether the RON component -- as an index of attentional reorientation after distraction -- is confined to a semantic task requiring working memory. In two ERP experiments we applied an auditory-visual distraction paradigm in which subjects were instructed to discriminate visual stimuli preceded by a task-irrelevant sound, this being either a standard tone (600 Hz, 88%) or a deviant tone (660 Hz, 12%). The visual stimuli were numbers which had to be judged on basis of a semantic (odd or even) or physical feature (either size or colour). As expected, deviance related ERP components namely the mismatch negativity (MMN), P3a, and RON were elicited. Importantly, the RON was affected by the variation of the task: within the semantic task an early RON and within the physical task a late RON was obtained. These results suggest that the RON component reflects two functionally distinct processes of attentional allocation after distraction: refocusing on task-relevant information on the working memory level, and general reorientation of attention, e.g. preparation for the upcoming task.

Acoustic Stimulation↗

PubMed2005

Diagnostic subgroups of developmental dyslexia have different deficits in neural processing of tones and phonemes.

The present study addressed auditory processing in 8-11-year-old children with developmental dyslexia by means of event-related brain potentials (ERP). Cortical sound reception was evaluated by recording N250 responses to syllables and tones and cortical sound discrimination by analyzing the mismatch negativity (MMN) to syllable and tone changes. We found that both cortical sound reception and sound discrimination were impaired in dyslexic children. The analysis of the data obtained from two dyslexic subgroups, Dyslexics-1 being impaired in non-word reading (or both non-word and frequent word reading) and Dyslexics-2 in frequent word reading but not in non-word reading, revealed that the MMN was specifically diminished in the latter group whereas it was normal-like in Dyslexics-1. However, no differences were found between these subgroups in sound reception as indicated by the responses elicited by the standard stimuli. These results show that different diagnostic subgroups of dyslexics have different patterns of auditory processing deficits as suggested by similarly impaired sound reception in both dyslexic groups and the sound-discrimination impairment specific to one of the groups.

Acoustic Stimulation↗

PubMed2004

Response repetition vs. response change modulates behavioral and electrophysiological effects of distraction.

If stimulation occasionally contains distracting information, behavioral responses to task-relevant aspects of the stimulation are prolonged and more error prone. Additionally, event-related potentials (ERPs) acquired in an auditory distraction paradigm show that the distracting information elicits the components mismatch negativity (MMN), P3a and reorienting negativity (RON). Here, we assess to what extent sequential dependencies in the stimulation influence such indicators of distraction. Data of four experiments were reanalyzed for response repetition and response change trials separately. Behavioral performance on Deviants suggests markedly smaller distraction effects in change compared to repetition trials. However, the presence of MMN-P3a-RON in both response repetition and response change trials shows that sequential features in stimulation do not dissolve distraction, but might substantially contribute to the (behavioral) effects measured in distraction paradigms and should be controlled for.

Acoustic Stimulation↗

PubMed2004

Distraction and reorientation in children: a behavioral and ERP study.

In the context of distraction, involuntary orienting to task-irrelevant deviations and the following reorienting to task-relevant stimulus information were studied in children aged 5-6 years. In an auditory distraction paradigm, reaction times were prolonged by 51 ms in trials including a task-irrelevant stimulus deviancy. Event-related potentials (ERPs) revealed a mismatch response (MMR) at 252 ms and a reorienting negativity (RON) 476 ms post-stimulus in response to deviating sounds. These behavioral and ERP effects resemble those reported for adults. We conclude that kindergarten children are prone to distraction, although they can quite effectively but not fully shield working memory operations from perturbating distracting information, and can recover from distraction in a similar way to adults.

Acoustic Stimulation↗

PubMed2004

Distraction effects in vision: behavioral and event-related potential indices.

Evidence is presented which shows that slight changes in serially presented visual input can be detected automatically and may result in behavioral distraction. In two experiments, reaction times on a two-alternative, forced-choice duration discrimination task were prolonged in trials where a task-irrelevant change in the location of the stimulus occurred. The P1 and N1 components of the event-related potential were enhanced in such trials. However, electrophysiological and behavioral effects were not affected when the duration discrimination was made more difficult and the N1 amplitude increase and RT prolongation were confined to situations where task-irrelevant location changes were infrequent. Thus, these effects most probably reflect pre-attentive change detection and subsequent distraction in vision, whereas the P1 effect is probably due to spatial eccentricity.

Adult↗

PubMed2004

Bottom-up influences on working memory: behavioral and electrophysiological distraction varies with distractor strength.

The present study investigates bottom-up effects serving the optimal balance between focusing attention on relevant information and distractibility by potentially significant events outside the focus of attention. We tested whether distraction, indicated by behavioral and event-related brain potential (ERP) measures, varies with the strength of task-irrelevant deviances. Twenty subjects performed a tone-duration discrimination task (200 or 400 ms sinusoidal tones presented equiprobably). The stimuli were presented with frequent standard (p = 0.84; 1000 Hz) or infrequent deviant (p = 0.16) pitch. These task-irrelevant pitch changes consisted in a frequency increase/decrease of 1%, 3%, 5%, or 10%. Each of them resulted in prolonged reaction times (RT) in the duration discrimination task and elicited the MMN, P3a, and RON components of the ERP. Importantly, these measures did increase as a function of pitch deviance. Separating the individual trials on the 1% deviation level into trials with and without RT prolongation, i.e., behavioral distraction effect, revealed that both subgroups had similar MMN, but P3a and RON were confined to the trials with RT prolongation. Results are interpreted within a model relating preattentive deviance detection, distraction, and working memory.

Adolescent↗

PubMed2003

Auditory distraction with different presentation rates: an event-related potential and behavioral study.

OBJECTIVE: The present study addresses the question of whether behavioral and electrophysiological effects obtained with the auditory distraction paradigm proposed by Schröger et al. [Clin Neurophysiol 2000;111:1450] depend on the timing of stimulus occurrence. METHODS: Subjects had to discriminate the duration of tones. Occasionally, task-irrelevant frequency changes were used as distractors. In 3 experiments the stimulus onset asynchrony (SOA) was manipulated: In Experiment 1, SOAs of 1500, 2000 and 3000 ms were used in separate blocks; in Experiment 2, 5 different SOA of lengths between 1300 and 2500 ms were used within the blocks; in Experiment 3, a constant SOA of 1400 ms was compared with a SOA of random lengths between 1300 and 1500 ms. Performance data was analyzed for distraction effects. Event-related potentials (ERPs) were examined for deviance-related components, i.e. the mismatch negativity (MMN), the P3a and the re-orienting negativity (RON). RESULTS: Behavioral distraction effects were obtained in all experimental conditions. The electrophysiological data show MMN, P3a and RON for the deviating tones in all experimental conditions as well. CONCLUSIONS: The behavioral and electrophysiological deviance-related effects were not sensitive to the SOA manipulations. Therefore, the timing of the presentation can be adjusted to the proficiency level of the population to be tested without loosing the distraction effects.

Acoustic Stimulation↗

PubMed2003

Working memory controls involuntary attention switching: evidence from an auditory distraction paradigm.

One function of working memory is to protect current mental processes against interference. In contrast, to be able to react flexibly on unpredictable environmental changes working memory should not totally be encapsulated from processing task unrelated information; that is, it should remain distractible. By manipulating the task load of the primary task in an auditory distraction paradigm we investigated how these opposing functions are coordinated by working memory. The behavioural results show that distraction effects were still present but reduced markedly with higher task demands. This suggests that working memory exerts some control over involuntary attention. In addition, event-related brain potentials related to the different processing stages reveal that the preattentive change detection system underlying distraction was not modulated by task demand whereas distraction per se was. The present data suggest that working memory is able to coordinate the maintenance of distractibility and the focus on the task at hand.

Acoustic Stimulation↗