The role of the accessory and main olfactory systems in maternal behavior of the primiparous rat

The objective of this study was to analyze the respective roles of the main and accessory olfactory systems in the development of maternal behavior in the primiparous Wistar rat. Females underwent one of the following treatments: vomeronasal nerve section (VN), irrigation of nasal cavities with 5% ZnSO4 solution (ZN), surgical control, saline irrigation control, and normal control. Surgical or first irrigation were done before mating occurred. Irrigations were done every 7 days thereafter. The dams and their litters were observed from the day the litter was born (Day 1) through Day 16. Pup weights and temperatures were recorded daily. Home cages were checked daily for changes in nest location and number of times pups were found out of the nest. Retrieving tests were conducted on Days 4, 7, 10, and 13. The following behavioral items were observed: number of pup retrievals , number of times mother nosed or licked pups, percentage of litter returned to nest by end of test, dam self-grooming, dam climbing or rising, and dam digging or burrowing in shavings. The VN dams and their litters were not significantly different from the control dams and their litters on any of the measures taken. The ZN dams and their litters were not significantly different from their controls on all measures except for pup body temperature which was slightly lower from Day 13 through day 16 and pup body weight which was slightly lower from Day 12 through Day 16. Since these differences are very small, they do not seem to indicate a serious deficiency in maternal behavior. The results indicate that adequate maternal behavior develops with either of the two systems intact.     

A word’s meaning affects the decision in lexical decision

The influence of an isolated word’s meaning on lexical decision reaction time (RT) was demonstrated through four experiments. Subjects in two experiments made lexical decision judgments, those in a third experiment pronounced the words used in the lexical decision task, and those in a fourth experiment quickly pronounced their first associative response to the words. Differences in lexical access time for the words were measured with the pronunciation task, and differences in meaning were assessed with the association task. Multiple regression analyses of lexical decision RT were conducted using associative RT, pronunciation RT, and other target word properties (printed frequency, length, instance dominance, and number of dictionary meanings) as predictor variables. These analyses revealed a relationship between lexical decision RT and associative RT after the effects of other variables had been partialed out. In addition, word frequency continued to have a significant relationship to lexical decision RT beyond that shared with pronunciation RT and the other variables. The results of these experiments indicate that at least some of the effect of word meaning and word frequency in lexical decision is attributable to a decision stage following lexical access.     

Lateral asymmetry of personal optimism

By combining models of cerebral emotional asymmetry and unilateral hemispheric activation, it was hypothesized that orienting to the right would produce greater personal optimism about future events than would orienting toward the left. This was supported significantly in two experiments which differed from each other in their manipulations, hypothetical future events, means of responding, and settings. The results supported previous research on unrealistic optimism and extended the concept to show the effect of induced lateral orientation. It was proposed that this effect is mediated by mood, and possibly by perceived control, and that this methodology can be extended to other behaviors which have proven amenable to mood manipulation.     

Stimulus selection in passive avoidance learning and retention: weanling, periadolescent, and young adult rats

Periadolescent rats exhibit a number of behavioral differences in comparison with younger or older animals. For instance, periadolescents tend to show enhanced acquisition of simple active avoidance tasks, but impaired acquisition of more complex appetitive and aversive discriminations. In this experiment, rats were trained on a simple passive avoidance task at one of three ages, as weanlings (25 days), periadolescents (35 days), or young adults (45 days). Training occurred in the presence of both a redundant discriminative stimulus and a specified, redundant contextual stimulus. The periadolescents did not differ from either younger or older rats in rate of learning the passive avoidance task. The retention performance of these animals was then tested following a change in either, neither, or both of the redundant cues. When a measure of performance that controls for baseline activity was used, it was observed that periadolescents were not disrupted by a change in the redundant discriminative stimulus, a cue change that clearly disrupted performance in 25- and 45-day-old animals, and tended to be more disrupted by the contextual change than younger or older rats. It is hypothesized that the alterations in performance exhibited by periadolescents may be related to an ontogenetic alteration in stimulus selection modulated by the catecholaminergic systems.     

The temporal structure of motivation. V. A within-episodes analysis of priming and provocation

Rats provided with chronic, continuous access to intracranial self-stimulation (ICS) exhibit discrete episodic response patterns. Response episodes under two conditions were examined for systematic trends in the spacing of times between successive responses (interresponse times; IRTs) to better identify the motivational bases of ICS. Three trends were observed in self-initiated and experimenter-provoked episodes. First, initial responses of spontaneous episodes typically had declining interresponse times. Second, this trend was not present when responses were provoked rather than spontaneous. Third, absolute times between responses varied across conditions, with provoked behavior having significantly lower initial IRTs. The findings suggest that for spontaneously initiated responding a transient facilitatory process cumulates at the beginning of ICS episodes. For provoked responding, it is possible that a manipulation which increased the initial probability of responding over time may have done so by maximizing an initial phasic priming process. At their onset, spontaneous and provoked episodes may be characterized by quantitatively differing motivational profiles.     

Postsurgical enrichment aids adult hemidecorticate rats on a spatial navigation task

The effect of environmental enrichment on normal rats, rats that received hemidecortication at birth, and rats that received hemidecortication when adult was studied in the Morris water task, which is a spatial navigation task requiring the use of distal cues for successful performance. Enrichment was achieved by housing the rats for 90 days in a large outdoor compound that was designed to model a natural environment. Adult hemidecorticated lab-raised rats were severely impaired in the acquisition of the task but neonatally hemidecorticated rats, although also impaired, showed significant sparing. Postsurgical, but not presurgical, enrichment of adult hemidecorticated rats significantly enhanced their recovery. Enrichment had little effect on neonatally decorticated rats or on normal rats. Although there were no gross anatomical changes associated with enrichment, the paradigm provides both a robust phenomena and a cortically dependent task that is ideal for investigating the processes in the remaining intact hemisphere that must support recovery.     

Intrinsic enjoyment and boredom coping scales: Validation with personality,evoked potential and attention measures

This paper reports the validation of brief, self-report measures of intrinsic enjoyment and boredom coping. Intrinsic enjoyment is characterized by intense involvement, interest and absorbed concentration; boredom coping is designed to reflect the disposition to restructure one's perceptions and participation in potentially boring activities so as to decrease boredom. Both traits are hypothesized to reflect the capacity for good attentional control across a variety of situations. Reliability was established by test-retest correlation and by an inter-item consistency measurement. Construct validity was established by comparison with previously-validated personality tests, real-life measures (such as Random Activities Experiential Sampling, which involves repeated self-report measures in daily life), as well as with laboratory measures of attention (including the averaged visual evoked potential (EP) and the Continuous Performance Test). Intrinsic enjoyment is significantly correlated with an independent measure of intrinsic involvement (low wish to be elsewhere in one's daily life), the affective experience of potency, self-reports of concentrating well with ease, high ego development, an internal locus of control, lack of boredom susceptibility and certain EP indices of attentional change and ‘cortical’ augmenting. Boredom coping is associated with a higher percent of time actually spent alone, high continuous performance task measures of attentional capacity, and low MMPI and Research Diagnostic Criteria indices of psychopathology.     

Common response processing and psychological refractoriness

This experiment examined whether structural considerations, that is the functional closeness of limb control centres (Kinsbourne and Hicks 1978), have a role to play in common processing models of psychological refractoriness. A typical double stimulation paradigm was used (Kantowitz 1974). On experimental trials, subjects responded with the right hand (RT1) to an auditory signal (0.80 probability). After a varied interstimulus interval (ISI) of 100, 200, 300 or 700 msec, one of three lights corresponding to one of the other limbs provided the signal for the second response (RT2). Control trials for RT1 and RT2 involved both stimuli, but subjects were required to make only one response. Results indicated that experimental RT1 was lengthened considerably over control values. While typical double stimulation effects were found at short ISIs, that is RT2 was lengthened, RT2 at long ISIs was actually faster than double stimulation control values. Although the RT results were not in a pattern that would be predicted by functional distance (Kinsbourne and Hicks 1978), within subject correlations of RT1 and RT2 by limb condition suggest that structural considerations may have a role to play. While within subject correlations were positive at all levels of ISI, they decreased as the interval between the two signals increased. The implications of these results for common processing models are discussed.     

Interpersonal problem solving in preschool children: A comparison of assessment procedures using two-dimensional versus three-dimensional stimuli

Two procedures for assessing the social problem-solving strategies of young children were compared: a traditional measure using pictorial stimuli and an alternative measure in which problems were presented using three-dimensional props. Subjects were 48 preschool children ages 3, 4 and 5. Using a counterbalanced, repeated measures design, the two tasks were presented to the children on consecutive days. Children also received the PPVT, and teacher ratings of behavioral adjustment were completed. Children gave more responses and suggested a greater variety of problem-solving strategies when tested with props than when tested with pictures. Response differences to the two testing procedures were greatest for children who were rated by their teachers as impulsive. Results are discussed in terms of the representational competence of the preschool child. Implications of the findings for intervention strategies also are discussed.