Sex-dependent habituation to novelty in rats

Male and female rats were familiarized with one-half of an exploration box for 30 or 60 minutes. When later tested, females showed higher preferences for the other novel half than males. Females also showed higher levels of rearing and ambulation. No sex differences were evident for grooming, freezing or defecation. The results were interpreted as females having habituated to the forced-exposure novelty of the familiar half of the apparatus more rapidly than males when the familiarization period was relatively short. With a longer period, males would have had more time to reach a similar level of habituation to that attained by females familiarized for 30 minutes. Relationships between novelty preferences and both rearing and ambulation as indices of exploration were also discussed in the light of significant correlations for males only.     

Sex differences in spontaneous alternation and open-field behavior of hamsters: Habituation differences

With a minimal intratrial interval, male golden hamsters spontaneously alternated significantly less often in a T-maze than females. Since there was no sex difference in choice latencies, the alternation difference could not be accounted for by longer intertrial intervals experienced by males. Instead, the difference was ascribed to faster rates of habituation to novelty in females because they showed greater between-sessions declines in open-field ambulation than males. From an analysis of rearing scores it was concluded that attempts to escape from the apparatus may have been the principal motivating influence in both the T-maze and open field.     

Sex differences in rats' response to novelty measured by activity and preference

Rats were familiarized to one compartment of a test box and then given access to this and a novel compartment. Females spent more time in the novel compartment than males did and this difference was found to be independent of a possible difference in familiarity with the familiar compartment arising from the females' higher frequency of ambulating and rearing with sniffing during familiarization. This is evidence of a sex difference in response to novelty independent of activity differences. Females also had shorter approach latencies to the novel compartment. These sex differences could reflect differences in either fearfulness or curiosity.     

Sex differences in spontaneous alternation and open-field behavior of hamsters: Habituation differences

With a minimal intratrial interval, male golden hamsters spontaneously alternated significantly less often in a T-maze than females. Since there was no sex difference in choice latencies, the alternation difference could not be accounted for by longer intertrial intervals experienced by males. Instead, the difference was ascribed to faster rates of habituation to novelty in females because they showed greater between-sessions declines in open-field ambulation than males. From an analysis of rearing scores it was concluded that attempts to escape from the apparatus may have been the principal motivating influence in both the T-maze and open field.     

Sex Differences in Novelty-related Location Preferences of Hooded Rats

In a square exploration box comprising a familiar and a novel half, hooded rats of both sexes were confronted with brightness differences between the two halves, brightness changes in the novel half, and attenuation of odour cues. Only males showed a significant preference for occupying the novel half when it had been visible but physically inaccessible during prior confinement to the familiar half. Although the brightness differences and changes did not affect the rats' novelty-related location preferences, preferences were lower whenever the novel half was white. This obvious brightness aversion was accentuated by a change from black to white. Attenuation of odour cues by washing the apparatus resulted in males (as well as females) failing to show a preference for the novel half. It was concluded that, although disparities in the specific type of visual information provided did not affect preferences, female rats appeared able to familiarize themselves with the future novel half through being able to see into it, whereas males may have required odour information for this to occur.     

Neophobia in spontaneous hypertensive (SHR) and normotensive control (WKY) rats

Latency of approaching a novel object (white-colored cube) placed in an unfamiliar open field, duration of object exploration, ambulation, rearing, grooming, and defecation were investigated in spontaneous hypertensive rats (SHR), their genetic normotensive controls (WKY), and standard Laboratory rats of Wistar origin (Tif:RAIf). The parameters measured were taken as indices of fear due to novelty (neophobia). Remarkable differences in behavior of all three strains were observed. By comparison to RAIf and WKY rats, SHR showed decreased neophobia as reflected in the significantly shorter latency of approaching the object and enhanced ambulation and rearing activity in the open field. By comparison to RAIf rats SHR also showed reduced grooming and defecation. WKY rats distinguished themselves from both SHR and RAIf by almost total absence of all responses in this test situation. This behavioral suppression was antagonized by 7.5 mg/kg ip of chlordiazepoxide. The results of this study further support the notion that, by comparison to standard laboratory rats, both SHR and WKY rats show possible genetically determined, altered behaviors which are diametrically opposite to each other.     

Effects of age on novelty reactions and exploration in rats

Female rats of three ages (approximately 39, 160 and 316 days) were individually observed in an exploration box which consisted of a novel and a familiar half. By means of a behaviour-sampling technique it was recorded which half of the box the rat was in and what sort of activity it was engaged in at the end of each of 90 10-sec. periods. The number of 8 × 8 in. units entered was also recorded. All rats were seen in the novel half more often than in the familiar half and this novelty preference was greatest for the youngest rats. However, exploration and inter-unit locomotion scores tended to be lower with the younger animals. For all three groups these two scores showed a significant decrement during an observation period.     

Visual novelty preference as a measure of recognition memory in moderately, severely, and profoundly retarded persons

A novelty preference method was used to examine memory processes in profoundly, severely, and moderately retarded persons. After viewing a photograph of a face for 30 seconds, subjects were shown the study face and a new one after intervals ranging up to 3 minutes. Data were obtained from 30 of 56 subjects with this method. Of the 30 subjects, 20 showed significant preference for looking at the new face in the test. Recognition memory as indexed by novel looking declined over the retention interval. Memory was stronger but decayed more rapidly for higher memorable (distinctive) faces. With refinement, the novelty preference method holds promise for the study of cognitive processes in nonverbal persons. But, since memory is being inferred from response preferences which reflect an induced motivational state, satiation, the relationship between this state and memory must be established.     

Sex differences in maternal behaviors of immature rats: The role of emotionality

Immature rats are able to give maternal care to pups and may increase their inclusive fitness by helping newborn siblings. Immature males are generally reported to be more maternal than females. In this research we studied sex differences and the extent to which they may be due to a different emotional response to novelty. We studied maternal response in two groups of immature rats of both sexes: in the naive group, juveniles aged from 18 to 30 days were given one test and showed clear-cut sex differences. The experience group was submitted to repeated tests from 18 to 30 days of age, thus eliminating the effects of novelty: as a result, all differences between sexes disappeared. A second experiment was designed in 24-day-old females to differentiate the effects of repeated handling and exposure to the test situation from that of repeated exposure to pups; moreover, the effects of an anxiety-reducing drug (diazepam) were studied. Exposure to pups is particularly efficient in facilitating maternal response. Diazepam injection was also effective, but its control showed that the injection per se was responsible for the effect. In conclusion, our results stress the importance of response to novelty and suggest that sex differences in maternal behavior of immature rats may be modulated by different emotional responses by males and females. In fact, emotionality competes with, and may exert an inhibitory effect on, the expression of a vast array of behaviors. © 1994 Wiley-Liss, Inc.     

Altered grooming responses to stress in rats exposed prenatally to ethanol

The effects of prenatal alcohol exposure on grooming, locomotion, and rearing in response to stress were examined in adult rats whose mothers consumed a liquid diet containing 35% ethanol-derived calories (EDC). Offspring of both pair-fed 0% EDC mothers and ad libitum chow-fed mothers were included as controls. In Experiment 1, females groomed more than males following placement into a novel test chamber, but no differences due to prenatal treatment were observed. Ethanol-exposed animals groomed more than controls following the stress of a forced 1-min swim (Experiment 2), but when rats tested in Experiment 1 were observed again after forced swim stress (Experiment 3), no differences due to prenatal treatment or sex were observed. Experiment 4 examined the effects of pretreatment with 1 mg/kg naloxone on novelty-induced grooming and as in Experiment 1 prenatal treatment did not affect grooming responses. Females again groomed significantly more than males and naloxone reduced grooming equally for all groups. The results suggest that novelty-induced grooming is a sex-influenced behavior, with females grooming more than males, and that animals exposed prenatally to alcohol and tested as adults may have altered responses to certain stressors (i.e., forced swim) under specific conditions. The altered grooming response of alcohol-exposed rats to swim stress can be eliminated by preexposing them to novelty stress.     

Pattern-line effects and units of visual processing in infants

In two experiments, we used the familiarization-novelty preference procedure to investigate the mechanism producing the pattern-line effect previously observed in 3- and 4-month-old infants. In the first experiment, we demonstrated the pattern-line effect as evidenced by the significantly higher novelty preference when infants were both familiarized and tested with mirror-image line elements embedded in a right-angle framework than when the infants were familiarized and tested with the same-line elements in isolation. We also observed a significant novelty preference when infants were familiarized with an isolated-line element, but tested with the elements embedded in context and a marginally significant preference when infants were familiarized with an element in context and then tested with the isolated elements. These results cast doubt on a strict emergent feature explanation of the pattern-line effect. In a second experiment, infants were shown to generalize habituation on the basis of configural information. The overall pattern of results is consistent with both the global-to-local (Navon, 1977) and levels of information (Enns & Prinzmetal, 1984) accounts of the pattern-line effect.     

Free-operant comparisons of wild and domestic Norway rats.

Wild and domestic rats (Rattus norvegicus) were compared on nondifferential appetitive variable interval responding, discrimination, and discrimination reversal procedures. The effects of strain, sex, deprivation, preexperimental handling, and sessions on response rate were examined. Performances during the 60 days of variable interval training showed prolonged increases over that period for all strain-sex groupings, with domestic subjects responding at higher rates than wild. Males also tended to respond at higher rates than females. During the discrimination procedure wild subjects showed more resistance to extinction than did the domestic subjects, although these differences generally diminished after the 30 days of training. During the discrimination reversal procedure domestic subjects reversed their responding pattern more readily than did the wild subjects, and domestic females reached criterion significantly sooner than domestic males. The effects of deprivation and handling were not significant during the experimental procedures.     

Effect of postweaning social experience on response of Siberian hamsters (Phodopus sungorus sungorus) toward young

Between 18 and 50 days of age, Siberian hamsters were housed either with same-sex littermates, opposite-sex littermates, opposite-sex littermates and parents, or opposite-sex littermates, parents, and a younger litter. When adults, these animals were presented with two 3-8-day-old pups for 8 hr, and their responses were recorded. Rearing conditions did not affect behavior of females. Males housed with female littermates in the absence of a younger litter showed fewer pup attacks and more nesting with pups than did males housed only with other males. Thus, housing with females in the early postweaning period may influence males' later (adult) responses toward pups. Only among hamsters housed with same-sex littermates did males and females differ in their response to pups, a result emphasizing that sex differences in behavior may depend on early social rearing.     

Septal damage in infant and adult rats: Effects on activity,emotionality, and muricide

Septal lesions produced signs of increased emotionality in the adult rat, the septal syndrome (hyperresponsiveness to handling; in the open field: decreased rearing and ambulation activity, increased defecation, deficient habituation) being more or less complete and more or less marked depending on the age at which the lesion was performed (7 days or 3 months), the extent of the lesion (restricted to the septum or extending to more ventrally located structures) and the environmental conditions in which the animals were reared (in groups or in isolation). All septal lesions provoked a similar and significant increase in the probability of occurrence of mouse-killing behavior, irrespective of age of operation, extent of lesion and kind of rearing environment. In a 24-hour actography starting at 11:30 a.m., the rats septalectomized at adult age were less active than controls during the initial period, while all septals were markedly more active than controls during the night period. Early septal lesions only transiently disrupted weight gain. The results obtained point to complex interactions between the effects of early brain damage and environmental conditions.     

Representation of the gender of human faces by infants: a preference for female

Six experiments based on visual preference procedures were conducted to examine gender categorization of female versus male faces by infants aged 3 to 4 months. In experiment 1, infants familiarized with male faces preferred a female face over a novel male face, but infants familiarized with female faces divided their attention between a male face and a novel female face. Experiment 2 demonstrated that these asymmetrical categorization results were likely due to a spontaneous preference for females. Experiments 3 and 4 showed that the preference for females was based on processing of the internal facial features in their upright orientation, and not the result of external hair cues or higher-contrast internal facial features. While experiments 1 through 4 were conducted with infants reared with female primary caregivers, experiment 5 provided evidence that infants reared with male primary caregivers tend to show a spontaneous preference for males. Experiment 6 showed that infants reared with female primary caregivers displayed recognition memory for individual females, but not males. These results suggest that representation of information about human faces by young infants may be influenced by the gender of the primary caregiver.     

Crossfostering in mice selectively bred for high and low levels of open-field thigmotaxis

The main purpose of this research was to investigate whether the difference in open-field (OF) thigmotaxis between mice selectively bred for high and low levels of wall-seeking behavior originated from genetic or acquired sources. Unfostered, infostered, and crossfostered mice were compared in two experiments in which the effects of strain, sex, and fostering on ambulation, defecation, exploration, grooming, latency to move, radial latency, rearing, thigmotaxis, and urination were studied. These experiments revealed that OF thigmotaxis was unaffected by the foster condition and thus genetically determined. The selected strains of mice also diverged repeatedly with regard to exploration and rearing. The findings are in line with the previously described existence of an inverse relationship between emotionality and exploration.     

Factors Affecting the Psychodiagnostic Significance of Color Perception

50 males, 17 and 18 years of age, and their natural parents were given the Blacky Defense Preference Inventory to determine if there are commonalities of defense preferences within families and within sex groups.

The results tended to support the hypothesis that male adolescents manifest defense preferences more similar to those of their father than to nonrelated adult males but failed to support a comparable hypothesis concerning the adolescent's similarity of defense preferences to his mother versus nonrelated adult females. The adolescent males did not reveal defense preferences more similar to those of their father than of their mother nor were sex differences in defense preferences observed. An additional finding suggested that the adult males are more heterogeneous in their defense preferences than are adult females.     

A strict response criterion yields a mirror effect in the novelty paradigm

According to the novelty/encoding hypothesis (NEH; Tulving & Kroll, 1995), efficacy of encoding information into long-term memory depends on the movelty of the information. Recognition accuracy is higher for novel than for previously familiarized material. This novelty effect is not a mirror effect: the superiority of novel over familiar items is not found in the hit rates but only in the false-alarm rates. The main result in the present replication study was that novel hit rates were higher than familiar ones when the most confident responses were examined separately, and thus a mirror effect could be demonstrated for these data, for both the low- and the high-frequency words. Similarly, the word-frequency effect on hits was stronger when a stricter response criterion was applied. It was concluded that the novelty effect and the word-frequency effect are more similar to one another than has hitherto been thought.     

The Vocational Preference Inventory scores and environmental preferences

This study investigated the relationship between vocational interest as measured by the Vocational Preference Inventory and preferences of 175 undergraduates for structured or unstructured environments. Males having clear-cut preferences for structured situations had significantly higher Realistic-Conventional scores than those not having those preferences (p < .05). Additionally, males with structured preferences had significantly lower Social-Artistic scores (p < .025). Results for females were similar, but not statistically significant. Males also had significantly higher (p < .01) Realistic-Conventional scores than females. The significant relationships between VPI scores and preferences for structured and unstructured situations support Holland's contention that interest scores are expressions of personality needs.     

Fighting,nonagonistic social behavior,and exploration in isolation‐reared rats

Sixty hooded Long‐Evans rats were assigned to one of three conditions: isolation‐rearing (from 14–30 days of age), brief isolation (from 28–30 days of age), and normal (no isolation). From day 14 to day 21, the isolation‐reared animals were maintained in an incubator set at 35°C to prevent hypothermia and were separated from each other by Plexiglas. They learned to nourish themselves by lapping milk that continuously flowed down one side of the enclosure. Thereafter, they were housed in standard hanging wire cages. Unlike previous studies of isolation at this age, there were no significant weight differences between the isolation‐reared group and the two control groups. At 30 days of age, the three groups were compared on fighting (serious and play), nonagonistic social behaviors (following and crawling under), and exploratory behavior (open‐field ambulation). The isolation‐reared group was significantly different from the normal group on all measures (isolates were higher on all measures except exploration). The isolation‐reared animals showed significantly more serious fighting (aggression) than the brief isolation animals, whereas these two groups did not differ on other behaviors. This methodology allows for the study of isolation‐rearing without the nutritional confounds found in previous research and shows an effect on aggression that is not accounted for by recent isolation. Aggr. Behav. 25:211–223, 1999. © 1999 Wiley‐Liss, Inc.