Hemispheric asymmetry and human associative learning: Interactions with attention

In a previous study (Hugdahl & Brobeck, 1986) it was shown that Pavlovian conditioning to an auditory verbal conditioned stimulus (CS) initially presented only to the left cerebral hemisphere was stronger than when the same CS was presented to the right hemisphere. This was followed up in the present study by controlling for the possibility that the effect was caused by laterally biased attention. The study was performed using the “dichotic extinction paradigm,” which consists of three different phases. During the habituation phase, the CS+ and CS- were presented binaurally and separated in time. During the acquisition phase, the CS+ was followed by a white-noise unconditioned stimulus (UCS). During the dichotic extinction phase, the CS+ and CS- were presented dichotically, i.e., simultaneous presentations on each trial. Half of the subjects had the CS+ in the right ear, and half had the CS+ in the left ear. Each group was further divided into two subgroups, with one subgroup instructed to attend only to the right ear input, and the other subgroup to attend only to the left ear input. During acquisition, larger electrodermal responses were obtained to the CS+ than to the CS-. During dichotic extinction, the CS+ right ear group showed superior resistance to extinction compared to the CS+ left ear group, with no effect of the manipulation of attention. The effect was, however, attenuated when levels of acquisition was used as covariates in an analysis of covariance. There were overall larger responses from the left hand recording.     

Brain asymmetry and autonomic conditioning: Sensitization control

In the present experiment we report effects of cerebral asymmetry, or laterality, during classical conditioning to facial emotional stimuli. Twenty-five female subjects were presented with slides of a happy face in one visual half-field (VHF), and simultaneously a slide of an angry face in the other VHF, followed by shock as the unconditioned stimulus (UCS). To control for effects of sensitization, a new stimulus, never associated with the UCS, was introduced in the extinction phase. Dependent measures were phasic heart rate responses (HR) and skin conductance responses (SCR). The HR results showed a significant right hemisphere effect for the CS-UCS association, that was not attributable to UCS sensitization. No significant effects were found for the SCRs. The basic HR finding was a right hemisphere superiority for learning of a conditioned association.     

Young children's storage behavior in a memory-for-location task

Two experiments concerned with children's intentional preparation for future retrieval in a memory-for-location task are presented. In the first experiment, 3-, 5-, 7-, and 9-year-olds were instructed to store and subsequently retrieve an object on a large spatial display. All age groups, except the 3-year-olds, tended to store the object at distinctive locations and their retrieval performance was facilitated accordingly. The four age groups did not differ in the types of selections made in a nonmemory control task. The second experiment dealt with the effects of feedback and informational factors on strategy acquisition. Preschoolers were given experience at retrieving the object from distinctive and nondistinctive positions on the stimulus display. Later, when instructed to store the object by themselves, older preschoolers produced the distinctive-position storage strategy following a feedback procedure in which they directly observed the consequences of their retrieval selections. The strategy was adopted by younger preschoolers, but only when additional strategy and task information accompanied visual feedback. The use of external memory tasks with young children and factors affecting strategy acquisition and utilization are discussed.     

Psychological characteristics of elderly insomniacs

Sixty insomniacs, aged 60 years or over, fulfilling the DSM-IV criteria for primary insomnia, completed a set of questionnaires measuring psychological distress. These included the Sleep Impairment Index (SIM), the Symptom Check List 90-Revised (SCL-90-R), the Penn State Worry Questionnaire (PSWQ), the Toronto Alexithymia Scale-20 (TAS-20) and the Elders Life Stress Inventory (ELSI). The insomniacs were compared on these measures with two contrast groups, one of elderly good sleepers and one an elderly community sample. As norms were developed for the SCL-90-R and PSWQ, insomniacs were also contrasted with the norm groups on these measures. In general, the results indicated a higher level of psychological distress among insomniacs than among the good sleepers, while there were negligible differences between insomniacs and the community sample on most measures. Overall, elderly insomniacs scored higher on measures of worry compared with the other groups, followed by measures of somatization, obsessive-compulsion and depression. It is concluded that excessive worrying was the most characteristic feature of elderly insomniacs.     

An event-related potential evaluation of involuntary attentional shifts in young and older adults

Involuntary shifts in attention to irrelevant stimuli were studied in elderly and young volunteers during a dichotic-listening task. Event-related potentials and behavioral measures were recorded. Volunteers heard pairs of tones presented with 2 different stimulus onset asynchronies (SOAs). To-be-ignored tones were presented to the left ear, followed by to-be-attended tones to the right ear. Left-ear tones were a frequent standard (700 Hz) and an infrequent small (650 Hz) and large (500 Hz) deviant. Right-ear tones (1500 Hz) were presented with 2 equiprobable intensities. Volunteers responded to the lower intensity stimulus. Behavioral performance was impaired at the short SOA when to-be-ignored large deviants preceded to-be-attended targets, but more so for the elderly volunteers. Large deviants also elicited the mismatch negativity (MMN) and P3a for both age groups. It was concluded that the more impaired behavioral performance observed for the elderly was due to greater sensitivity to output from the MMN system by a frontal lobe system responsible for the maintenance of attentional focus.     

Infant responsiveness and maternal confidence in the neonatal period

Responsiveness in prematurely and term-born infants was studied cross-sectionally in relation to maternal confidence. Orientation and arousal were measured in 140 prematurely (mean BW 1,398 g, GA 30.1 weeks) and 75 term-born infants (mean BW 3,613 g, GA 39.3 weeks) with the Neonatal Behavioral Assessment Scales. Mothers filled out the Maternal Confidence Questionnaire and a modified version of the Parenting Stress Index. Prematurely born infants had a significantly lower level of arousal than term-born neonates. Responsiveness was not associated with maternal confidence. Lower confidence was associated with primiparity in both groups of mothers. Multiparous mothers of prematurely born infants had significantly lower levels of confidence than multiparous mothers of term-born infants. Confidence was significantly associated with stress for mothers of prematurely and term-born infants, and may be focused in follow-up after giving birth. Prematurely born infants should be examined more thoroughly in aspects of arousal at the time of discharge.