Effects of a violation of an expected increase or decrease in intensity on detection of change within an auditory pattern

An infrequent physical increase in the intensity of an auditory stimulus relative to an already loud frequently occurring “standard” is processed differently than an equally perceptible physical decrease in intensity. This may be because a physical increment results in increased activation in two different systems, a transient and a change detector system (signalling detection of an increase in transient energy and a change from the past, respectively). By contrast, a decrease in intensity results in increased activation in only the change detector system. The major question asked by the present study was whether a psychological (rather than a physical) increment would continue to be processed differently than a psychological decrement when both stimuli activated only the change detector system. Participants were presented with a sequence of 1000 Hz tones that followed a standard rule-based alternating high-low intensity pattern (LHLHLH). They were asked to watch a silent video and thus ignore the auditory stimuli. A rare “deviant” was created by repeating one of the stimuli (e.g., LHLHLLLH. The repetition of the high intensity stimulus thus acted as a relative, psychological increment compared to what the rule would have predicted (the low intensity); the repetition of the low intensity stimulus acted as a relative, psychological decrement compared to what the rule would have predicted (the high intensity). In different conditions, the intensity difference between the low and high intensity tones was either 3, 9 or 27 dB. A large MMN was elicited only when the separation between the low and high intensities was 27 dB. Importantly, this MMN peaked significantly earlier and its amplitude was significantly larger following presentation of the psychological increment. Thus, a deviant representing an increment in intensity relative to what would be predicted by the auditory past is processed differently than a deviant representing a decrement, even when activation of the transient detector system is controlled. The psychological increment did not however elicit a later positivity, the P3a, often thought to reflect the interruption of the central executive and a forced switching of attention.     

The chronometry of mental ability: An event-related potential analysis of an auditory oddball discrimination task

The relation between intelligence and speed of auditory discrimination was investigated during an auditory oddball task with backward masking. In target discrimination conditions that varied in the interval between the target and the masking stimuli and in the tonal frequency of the target and masking stimuli, higher ability participants (HA) displayed more accurate discriminations, faster response time, larger P300 amplitude, and shorter P300 and mismatch negativity (MMN) latency than lower ability participants (LA). Task difficulty effects demonstrated with variation in mask type indicate that the mask does not interfere with the detection of the deviant target stimulus, but rather that the target and mask are integrated as a single compound stimulus. The temporal effects suggest that the speed of accessing short-term memory is faster for HA than LA and, on the basis of the MMN latency, the effect is accomplished automatically, without focused attention. Moreover, the pattern of results obtained with these data support the view that the accuracy effects are determined by processing speed rather than discrimination ability. Comparator models that accommodate these effects are discussed.     

Interplay between acoustic/phonetic and semantic processes during spoken sentence comprehension: an ERP study

When listening to speech in everyday-life situations, our cognitive system must often cope with signal instabilities such as sudden breaks, mispronunciations, interfering noises or reverberations potentially causing disruptions at the acoustic/phonetic interface and preventing efficient lexical access and semantic integration. The physiological mechanisms allowing listeners to react instantaneously to such fast and unexpected perturbations in order to maintain intelligibility of the delivered message are still partly unknown. The present electroencephalography (EEG) study aimed at investigating the cortical responses to real-time detection of a sudden acoustic/phonetic change occurring in connected speech and how these mechanisms interfere with semantic integration. Participants listened to sentences in which final words could contain signal reversals along the temporal dimension (time-reversed speech) of varying durations and could have either a low- or high-cloze probability within sentence context. Results revealed that early detection of the acoustic/phonetic change elicited a fronto-central negativity shortly after the onset of the manipulation that matched the spatio-temporal features of the Mismatch Negativity (MMN) recorded in the same participants during an oddball paradigm. Time reversal also affected late event-related potentials (ERPs) reflecting semantic expectancies (N400) differently when words were predictable or not from the sentence context. These findings are discussed in the context of brain signatures to transient acoustic/phonetic variations in speech. They contribute to a better understanding of natural speech comprehension as they show that acoustic/phonetic information and semantic knowledge strongly interact under adverse conditions.     

Cognitive control of language production in bilinguals involves a partly independent process within the domain-general cognitive control network: evidence from task-switching and electrical brain activity

In highly proficient, early bilinguals, behavioural studies of the cost of switching language or task suggest qualitative differences between language control and domain-general cognitive control. By contrast, several neuroimaging studies have shown an overlap of the brain areas involved in language control and domain-general cognitive control. The current study measured both behavioural responses and event-related potentials (ERPs) from bilinguals who performed picture naming in single- or mixed-language contexts, as well as an alphanumeric categorisation task in single- or mixed-task context. Analysis of switch costs during the mixed-context conditions showed qualitative differences between language control and domain-general cognitive control. A 2 × 2 ANOVA of the ERPs, with domain (linguistic, alphanumeric) and context (single, mixed) as within-participant factors, revealed a significant interaction, which also suggests a partly independent language-control mechanism. Source estimations revealed the neural basis of this mechanism to be in bilateral frontal-temporal areas.     

The impact of organisational change on professionals working within a Community Mental Health Team (CMHT): a psychodynamic perspective

The aim of this study was to explore the effects of organisational change upon staff working in a Community Mental Health Team (CMHT). A grounded theory methodology was employed to analyse data from eight interviews with a range of staff. Analysis identified one core category and five key categories. ‘Corrosion of good work: an ethos in decline’ represents the core category and refers to the staff members’ sense of demoralisation of their professional values and integrity. The first key category, ‘Cultural change’, refers to staff members’ perception of change within the CMHT, with an increased emphasis on regulation, performance management and proceduralisation. Three further key categories were identified: ‘Caring clinicians and uncaring managers’, ‘Confusion regarding professional roles’ and ‘Disconnecting and isolating’. The fifth key ‘Staff departing and increasing risk for clients’, describes the impact of the working culture. These categories and emerging theory were interpreted through a psychodynamic lens, and identified the need for better management practice, support, training and supervision of staff as the foundations of safe practice.