Secondary-task assessment of workload: neuropsychological considerations for applied psychology.

The secondary-task paradigm has enjoyed considerable success as an assessment technique for operators' workload. However, during the past several years experimental neuropsychologists have employed an almost identical paradigm in their research investigating cerebral lateralization of function. To date, these areas of literature have existed as relatively isolated bodies of work, largely due to the differences between the disciplines. In the present manuscript is a brief review of the results from neuropsychological secondary-task studies and a consideration of these results in terms of their implications for the measurement of operators' workload.

Cerebral lateralization of familiar and unfamiliar music perception in nonmusicians: a dual task approach.

In a dual task procedure that controls for attentional trade-off effects, asymmetrical interference effects were observed in dual task conditions of finger tapping and concurrent processing of familiar and unfamiliar music. Laterality effects suggested that perception of orchestral presentations is largely lateralized to the left hemisphere in both males and females. In a second dual task condition of vocalization and music processing, both males and females displayed interference in speech production during concurrent music processing. Males showed greater left hemispheric interference effects during simultaneous vocalization and music processing.

Cerebral lateralization of music perception in the dual task paradigm: unfamiliar melody recognition in sinistrals.

A dual task study of unfamiliar music perception during concurrent right and left hand finger tapping was conducted with a group of left-handed non-musicians. A pattern of symmetrical, bilateral suppression of finger tapping was observed during a concurrent music task of unfamiliar melody recognition. There was no evidence of trade-off effects in the dual task inasmuch as no interference in melody recognition was observed. The absence of attentional shifts strongly suggests that the bilateral symmetry in motor performance in the dual task condition reflects bilateralized cerebral organization among sinistrals for processing unfamiliar music.

Sex differences in the lateralization of spatial abilities: a spatial component analysis of extreme group scores.

Sex differences in the cerebral lateralization of two discrete components of spatial processing were investigated in high and low ability males and females using the dual-task paradigm. In the first phase of the experiment, the results indicated a pattern of right hemispheric control for a spatial visualization component, regardless of sex and ability level. In the processing of the spatial orientation component of spatial ability, high ability males and females showed left hemispheric lateralization, whereas low ability males and females displayed right hemispheric control. In the second phase of this study, it was observed that high ability females and low ability males may use a verbal mediation strategy in processing spatial visualization tasks. No verbal mediation effects were found for the spatial orientation component.

The effects of linguistic experience on cerebral lateralization for speech production in normal hearing and deaf adolescents.

The cerebral lateralization patterns for speech production in 57 normal hearing and deaf adolescents were studied using the dual-task paradigm. Normal hearing subjects showed left hemispheric dominance for speech production, whereas both the congenitally deaf and those with early acquired deafness showed atypical cerebral representation for speech production. Deaf subjects whose hearing loss occurred after 2 years of age displayed a pattern of mixed cerebral dominance related to complexity of speech production or task difficulty. These results are interpreted as evidence for a relationship between linguistic/cognitive stage of development and the ontogenesis of cerebral lateralization. A parallel lateralization hypothesis of left cerebral dominance for speech production is offered.

The effects of concurrent vocalization on foot and hand motor performance: a test of the functional distance hypothesis.

The effects of concurrent vocalization on hand and foot motor performance were examined in two dual-task experiments as a test of the functional distance hypothesis. No interference effects were found with either hand or foot tapping under two difficulty levels of verbal activity. There was no evidence of differential or asymmetrical interference patterns despite the differential functional and anatomical distances of these motor centers from the speech centers. Consequently, the data provided no support for the functional distance hypothesis.

Cerebral lateralization for speech in deaf and normal children.

The cerebral lateralization pattern for speech production in normal hearing and congenitally deaf children was studied using the dual-task paradigm. Performance under the verbal task conditions showed predicted left hemispheric dominance for speech production in the normal hearing children. No developmental trends in asymmetry were found, suggesting that speech lateralization is present in normal 3-year-old children. These data support the developmental invariance hypothesis of cerebral organization. Deaf children showed more symmetrical patterns of cerebral control for speech production. No developmental trends in functional brain organization were observed among prepubescent deaf children.

Neonatal stimulation, maternal behavior, and accelerated maturation in BALB/c mice.

An experiment was conducted to examine the effects of neonatal handling and hypothermia on infant physical maturation and growth and on maternal behavior in BALB/c mice. Stringent methodological and statistical controls were employed for experimenter bias and litter effects. No evidence appeared to support claims that neonatal stimulation leads to accelerated physical maturation. Alterations in maternal behavior patterns were found only immediately following hypothermia of pups. Maternal behavior did not correlate highly with offspring maturational rates, but maternal weight and age and pup birth weight were highly predictive of infant physical maturation.

The effects of tactile and kinesthetic stimulation on neonatal development in the premature infant.

The effects of tactile and kinesthetic stimulation on the neonatal development of 12 premature infants were investigated. Experimental infants received four 15-min periods of tactile and kinesthetic stimulation daily for 10 days. The control infants received only standard, routine nursery care. Data were collected daily on 8 dependent measures: weight, number of feedings, amount of formula intake, body temperature, respiration, heart rate, frequency of voiding, and frequency of stooling. The data analyses revealed significant differences in amount of formula intake and in weight at the end of the treatment period in favor of the experimental infants. Additionally, the experimental infants required significantly fewer feedings during the stimulation period. All others dependent measures were nonsignificant.

The effects of neonatal vestibular stimulation on adult growth and emotional reactivity in BALB/c mice.

Two experiments were conducted to determine the effects of neonatal vestibular stimulation on the subsequent development and behavior in BALB/c mice. No evidence appeared to suggest that neonatal vestibular stimulation alters either the growth pattern or the ontogenesis of emotional reactivity.