Biomedical subjects

C Rovee-Collier

Publications and source records attributed to C Rovee-Collier.

61 records · Page 4Linked to original sources

PubMed1986

Time budgets in growing chicks.

The manner in which rapidly growing chicks distribute their time among diurnal activities was measured in two studies in which the amount of available light was varied to match seasonal extremes. The effectiveness of the chick's time budgets was assessed in terms of the impact on growth. In Experiment 1, 24-hr patterns of feeding, drinking, nesting, and wheel-running were recorded during successive photoperiods with 12, 6, 18, and 12 hr of light when access to a social partner was concurrently available. In Experiment 2, access to a social partner was an exclusive activity. In both studies, chicks' 24-hr behavioral patterns in response to temporal constraints on their diurnal activities were surprisingly plastic, permitting them to defend a normal and high rate of growth. This was accomplished by changes in feeding rate and by nocturnal feeding rather than by systematic elimination of other diurnal activities. When sociality and feeding were competing activities, feeding time decreased and feeding rate increased such that contact with a conspecific as well as rapid growth were defended. The absolute amount of time spent in measured activities was invariant within subjects irrespective of age, photoperiod, or the number and type of activities recorded, providing evidence of time budgets in immature organisms. In both studies, buffer time (the amount of time spent in no activity) emerged as a significant aspect of the daily time budget that is defended through a variety of environmental challenges.

Animals↗

PubMed1986

Twilight activity and antipredator behavior of young fowl housed in artificial or natural light.

Twenty-four-hr patterns of running wheel activity (Experiment 1) and death feigning, an antipredator behavior (Experiment 2), were studied in domestic chicks housed outside, in natural lighting, or indoors, with light onset and offset timed to coincide with the upper limbs of local sunrise and sunset, respectively. Although chicks housed outside were more active and displayed stronger death feigning reactions, the daily patterns of each activity were highly similar in the two groups. Activity peaked during the period corresponding to evening twilight and was negligible during the morning twilight period; in contrast, death feigning peaked during the morning twilight period. Activity measures indicated that chicks on the artificial light schedule had learned to anticipate dark by day 5, and subsequent ontogenetic changes in activity occurred exclusively in the evening twilight phase.

Aging↗

PubMed1985

Specificity in the reactivation of infant memory.

In three experiments the specificity of an effective reactivation stimulus, or reminder, was examined. Two weeks after learning to produce movement in a crib mobile by footkicking, 3-month-old human infants showed no retention of the response-reinforcer contingency. A reactivation procedure 24 hours prior to the long-term retention test was effective if the reminder was a brief noncontingent exposure to the original 5-component training mobile or a mobile containing one novel substitution. When more than one novel component were substituted into the original mobile, the reminder was ineffective. This was predicted by the discrimination function 24 hours following training. A reminder containing only a single familiar (predictive) component and four novel ones was also moderately effective. In subsequent studies, we explored different interpretations of the reminder specificity effect. We hypothesize that reminder specificity is of particular adaptive value for developing organisms in providing a buffer against memory retrieval in inappropriate contexts.

Cues↗

PubMed1984

Classical conditioning and retention of the infant's eyelid response: effects of age and interstimulus interval.

Independent groups of 10-,20-, and 30-day-old infants were subjected to a classical eyelid conditioning procedure involving either a 500- or a 1500-msec interstimulus interval (ISI). Ten days later, all received a second conditioning session. A reliable increase in conditioned responding was observed at all ages but only by infants receiving the 1500-msec ISI. Although age was not a significant factor in any conditioning measure except final performance level, which was greater for the oldest than for the youngest group, it did influence long-term retention. A reliable memory component was observed in the Session 2 performance of infants initially trained at 20 and 30 days but not at 10 days. These data demonstrate the importance of temporal parameters in the formation of conditioned associations very early in infancy and provide evidence for the long-term behavioral consequences of those associations.

Acoustic Stimulation↗

PubMed1984

Expectancies and memory retrieval in three-month-old infants.

The ability of 3-month-olds to acquire generalized expectancies of reward and the role of these expectancies in memory retrieval was assessed in 2 experiments. In both, infants learned to activate the components of a crib mobile by kicking and were trained with mobiles containing either the same (invariant) or different (variable) components in successive daily sessions. In Experiment 1, infants exhibited positive transfer over both the invariant and variable stimulus series. However, there was a trend toward disruption of retrieval when infants were tested with a familiar set of components following training on a variable stimulus series. In Experiment 2, infants were trained for 2 sessions with mobile components that either did or did not change between sessions. In a 24-hour retention test, mobile components that either continued or violated the serial order established during the preceding sessions were presented as retrieval cues. Infants again exhibited positive transfer over both variable and invariant series when the test stimulus was predicted by the serial order of training stimuli, but violations of either expected order produced a retention deficit. These results were interpreted as suggesting that very young infants develop generalized expectancies of reward that are based on the serial pattern in which events occur.

Conditioning, Operant↗

PubMed1983

Memory retrieval: a time-locked process in infancy.

Three-month-old infants learned to activate an overhead crib mobile by operant footkicking and received a visual reminder of the event (a "reactivation treatment") 2 weeks later, after forgetting had occurred. Subsequent manifestation of the association was a monotonic increasing function of time since the reactivation treatment, and performance of infants tested 8 hours after the remainder was related to the time spent sleeping in the interim (r = 0.75). These data demonstrate that normal retrieval is time-dependent. Moreover, individual data suggest that retrieval may be continuous rather than discontinuous.

Humans↗

PubMed1980

The critical cues for diurnal death feigning in young chicks: a functional analysis.

The critical determinants of extended diurnal death feigning were assessed in a refinement experiment in which visual and tactile cues during rearing and/or testing were systematically eliminated. Ninety-five domestic chicks were reared in either a social environment or physical (tactile) isolation, and half in each rearing condition were reared and/or tested under conditions of visual restriction. As expected, social rearing was prerequisite to the manifestation of extended death feigning; however, the incidence and duration of death-feigning was attenuated by functional visual isolation of socially reared chicks during either rearing or testing. It was concluded that visual novelty of the environment is the minimal condition for sustained death feigning by young chicks in the daylight hours.

Animals↗