Computer signal detection by monitoring auditory evoked potentials

A digital computer, using a simple decision algorithm, attempted to determine when an acoustical signal had been presented to a cat by monitoring the amplitude of the evoked potentials (EP) at brainstem auditory nuclei. The signal-to-noise level at threshold and the shape and range of the decision model “psychometric functions” were similar to those obtained from humans in the same task. In addition, the detection performance obeys Weber’s law, the mean amplitude of the EP increases monotmonically with signal level, the variance of the amplitude is independent of both signal and noise level, and both the mean latency and the variance of the latency of the peaks decrease with increasing signal level. These findings suggest that the synchronization in firing of a population of single units plays a part in determining the amplitude of the EP. Interaural effects in detection performance were found at the inferior colliculus and, to a lesser extent, at the superior olive.     

Functional constraints on sentence processing: A cross-linguistic study

English and Italian provide some interesting contrasts that are relevant to a controversial problem in psycholinguistics: the boundary between grammatical and extra-grammatical knowledge in sentence processing. Although both are SVO word order languages without case inflections to indicate basic grammatical relations, Italian permits far more variation in word order for pragmatic purposes. Hence Italians must rely more than English listeners on factors other than word order. In this experiment, Italian and English adults were asked to interpret 81 simple sentences varying word order, animacy contrasts between the two nouns, topicalization and contrastive stress. Italians relied primarily on semantic strategies while the English listeners relied on word order—including a tendency to interpret the second noun as subject in non-canonical word orders (corresponding to word order variations in informal English production). Italians also made greater use of topic and stress information. Finally, Italians were much slower and less consistent in the application of word order strategies even for reversible NVN sentences where there was no conflict between order and semantics. This suggests that Italian is ‘less’ of an SVO language than English. Semantic strategies apparently stand at the ‘core’ of Italian to the same extent that word order stands at the ‘core’ of English. It is suggested that these results pose problems for claims about a ‘universal’ separation between semantics and syntax, and for theories that postulate a ‘universal’ priority of one type of information over another. Results are discussed in the light of the competition model, a functionalist approach to grammar that accounts in a principled way for probabilistic outcomes and differential ‘weights’ among competing and converging sources of information in sentence processing.     

Rhythmical body movement in sleep: a brief review and treatment study

Vigorous and damaging head-banging and head and body-rocking can occur in normal subjects of average intelligence before and during sleep. Reports of behavioural treatments for this are reviewed. Data from the present case and others suggest that waking plus efficient response prevention is sufficient to substantially reduce or eliminate the activity even when the treatment has been withdrawn for up to one year. The aetiology of the activity is not understood. However, this case suggests that head- and body-rolling, when long-established, need not enhance the quality of sleep since this was unimpaired on completion of treatment and was possibly even improved by the elimination of the movements. The present case also demonstrates that the behaviour can be treated successfully even when considerable environmental stresses occur.     

Attention and multidimensional discrimination1

Observers’ ability to perform several discrimination tasks at the same time was tested using a two-alternative temporal forced-choice procedure. Discrimination of two auditory dimensions (pitch and intensity) and two visual dimensions (horizontal position and vertical position) was measured under conditions where one, two or all four dimensions required attention. Three signal durations were used: 67, 133, and 200 msec. Increasing the number of dimensions requiring attention systematically reduces the precisions of discrimination for each dimension. Auditory and visual discrimination is affected similarly. The amount of reduction in discrimination is independent of whether the dimensions requiring attention involve the same or different sensory modalities. The data are analyzed for evidence of a constant processing capacity employed in both single and multidimensional discrimination. The possibility that the observed performance levels could be achieved by sequentially processing the simultaneous inputs is also considered.     

Suicidal Ideation in First‐Episode Psychosis (FEP): Examination of Symptoms of Depression and Psychosis Among Individuals in an Early Phase of Treatment

First‐episode psychosis (FEP) is a particularly high‐risk period for suicide, in which risk elevates by 60% within a first year of treatment as compared to later stages of illness. To date, much of the literature has focused on individuals with a longer duration of psychosis; thus, there is an urgency for research to examine suicide risk among individuals in FEP in the beginning stage of treatment. This study aimed to identify the relationships between demographic characteristics, symptoms of depression, psychosis (particularly positive symptoms of psychosis), and suicidal ideation among individuals in FEP. Secondary data were obtained from National Institute of Mental Health's Early Treatment Program of the Recovery After an Initial Schizophrenia Episode project (N = 404). Consistent with prior research, participants who experienced suicidal ideation during the study period reported having a longer duration of untreated psychosis and greater symptoms of depression. Further, positive symptoms of psychosis, namely hallucinations and delusions, were found to increase the odds of experiencing suicidal ideation. Findings point toward the implication that depression and positive symptoms of psychosis relate to the experience of suicidal ideation among individuals with a FEP and should be evaluated for and treated in the early stages of treatment.     

Teaching behavior analysts in an early intensive behavioral intervention setting to conduct a structured mealtime protocol

Children with autism spectrum disorder often display feeding problems, such as consumption of a limited variety of foods. It is also common for these children to be enrolled in early intensive behavioral intervention (EIBI) services for comprehensive treatment. Combined, these factors make it possible that behavior analysts will have a role in a child's clinical care related to feeding. However, given that the etiology of pediatric feeding disorders is complex and multifactorial, clinicians should ensure they have sufficient training and a setting that is appropriate for assessment and treatment. Therefore, we evaluated the effects of behavioral skills training in an EIBI setting to conduct a structured mealtime protocol. Training resulted in increases in procedural integrity, and we replicated these effects for all participants.     

Space and movement in working memory

Encoding seen movement of another human body requires visuo-spatial processing, and recall involves motor activity. However, encoding whole body movement patterns is affected differently by patterned and spatial secondary tasks, and this difference is reversed for encoding of spatial targets for movement (Smyth, Pearson, & Pendleton, 1988). The experiments reported here investigate the rehearsal of such movement patterns and their recall over unfilled and filled intervals. Performing, watching, or encoding a sequence of spatial positions while carrying a memory load of movement patterns did not affect recall of those movements, whereas performing, watching, or encoding a further set of patterned movements reduced the number recalled from the original set. However, memory for a series of locations in space was not affected by watching patterned movements during the interval, and only order information was affected by watching movement to a series of spatial locations during the interval. The results are discussed in terms of the independence of rehearsal mechanisms for spatial sequencing and movement patterns.