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Biomedical subjects

C Rovee-Collier

Publications and source records attributed to C Rovee-Collier.

At least 55 records · Page 3Linked to original sources
PubMed1993

Developmental consequences of diet and activity.

The effect of a protein-deficient and a protein-surfeit diet and continuous access to an activity wheel on food intake, growth, and body temperatures of behaviorally thermoregulating White Leghorn chicks was assessed in two experiments. In Experiment 1, both imbalanced-protein diets depressed intake and growth and differentially affected activity relative to a control diet, but activity did not ameliorate the deleterious effect of a high-protein diet on growth. Diet groups with continuous access to a running wheel did not differ on any measure from corresponding inactive dietary control groups. In Experiment 2, these results were replicated in a lower ambient temperature, and an effect of diet on body temperature emerged. Diets that affected spontaneous activity or body temperature also affected death feigning, a predation defense behavior. The data from behaviorally thermoregulating chicks are consistent with previous findings that activity does not depress growth rate in animals who cannot convert a portion of their intake into adipose tissue.

Animals↗
PubMed1993

Infants' eyewitness testimony: effects of postevent information on a prior memory representation.

In eyewitness testimony research, postevent information impairs retention of the original event and increases the probability that interpolated information will be identified as part of the original event. The present experiments studied these effects with 3-month-olds. Infants learned to kick to move a particular crib mobile and then were briefly exposed to information about a novel mobile. The novel postevent information impaired recognition of the original mobile when it immediately followed training but not when it was delayed by 1 day. Like adults, infants treated the postevent information as part of the original training event, continuing to do so for at least 2 weeks. We propose that postevent information displaces conflicting information coactive with it in primary memory and creates a new, updated memory token of the event. Once the new token leaves primary memory, however, it is protected; only a copy can be retrieved and modified in the future.

Association Learning↗
PubMed1992

Contextual coding and recoding of infants' memories.

Six-month-old infants recognize a well-learned cue 24 h after training in the original context but not in a different one. In the present studies, we demonstrated that this contextually based retrieval deficit could be overcome if, following some training experience in one context, infants were briefly and passively exposed to a novel context. The impact of this procedure was retroactive, leading the immediately preceding training episode to be contextually recoded. However, it did not override the debilitating effect of a novel context on memory reactivation 3 weeks later and, surprisingly, it blocked the effectiveness of the actual training context as a reminder. We conclude that each individual training episode is encoded in terms of the context in which it occurs. The memory of a given episode, however, is recoded in terms of the most recent context in which it is active. This mechanism permits memories that are highly context-specific to be updated and subsequently retrieved in new and potentially appropriate settings.

Association Learning↗
PubMed1992

Textons, visual pop-out effects, and object recognition in infancy.

Five experiments were conducted to determine whether primitive perceptual features, or textons, which Julesz (1984) identified in studies of texture segregation with adults, also affect object recognition early in development. Three-month-old infants discriminated Ts and Ls composed of overlapping line segments from +s but not from each other in a delayed-recognition test after 24 hr; however, Ts and Ls were discriminated from each other after only 1 hr. In a priming paradigm, Ts, Ls, and +s were discriminated from one another after 2 weeks. In succeeding experiments, infants exhibited adultlike visual pop-out effects in both delayed recognition and priming paradigms, detecting an L in the midst of 6 +s and vice versa; these effects were symmetrical. The pop-out effects apparently resulted from parallel search: Infants failed to detect 3 Ls among 4 +s. Clearly, some of the same primitive units that have been identified as the building blocks of adult visual perception underlie object recognition early in infancy.

Attention↗
PubMed1992

Long-term memory for context-specific category information at six months.

The ability of 6-month-old infants to remember a functional category acquired in a specific context was assessed in 3 experiments via an operant procedure in which infants learned to perform a specific action (a footkick) to activate an object suspended before them. In Experiment 1, infants trained with different exemplars in the same context transferred responding to a novel exemplar in the same but not a different context 24 hours later. Experiment 2 revealed that infants' reactivated memory of category training remained intact and context-specific after 3 weeks. In Experiment 3, a novel category exemplar was able to reactivate the forgotten memory of category training only in the encoding context. At 6 months, information about the place where categories are constructed is prerequisite for retrieval of a category concept from long-term memory. This requirement insures that early category concepts remain stable over relatively long periods.

Analysis of Variance↗
PubMed1991

Multiple contexts and memory retrieval at three months.

Studies of adults have shown that the contextual dependence of memory retrieval can be alleviated by training in multiple contexts. In the present studies with 3-month-old infants, retention was disrupted when infants were trained in one context and tested in another, but not when they were trained in multiple contexts prior to testing in a novel context. The retention advantage of multiple learning contexts was observed after 3 days in a simple forgetting paradigm (Exp. 1) and after 14 days in a reactivation paradigm (Exp. 2). These findings demonstrate that although the setting in which an event occurs is an important determinant of memory retrieval at 3 months, its protective function can be overridden by common experiences in varied settings.

Association Learning↗
PubMed1991

Behavioral thermoregulation and immobilization: conflicting demands for survival.

In three studies, core temperatures of immature chicks rose during immobilization induced by simulated predation and fell rapidly when immobilization terminated. Immobilization termination was predicted by proximity of the core temperature to the daily resting core temperature of adult fowl. Although immobilization duration increased with age and was shorter in cold and hot environments, immobilization terminated at the same core temperature at all ages and ambient temperatures. The common termination temperature and pattern of temperature change across all Ss suggests that immobilization is terminated in response to the demand that the rising core temperature be behaviorally maintained within a vital range. The generality of this finding was confirmed in a fourth study with preweanling kittens during exhibition of the transport response--an immobilization reaction with a different evolutionary history. These findings reveal that when immobilization and behavioral thermoregulation present conflicting survival demands for avian and mammalian young, the control of core temperature assumes behavioral priority.

Adaptation, Physiological↗
PubMed1991

Infant memory for place information.

The present studies were designed to examine the role of place cues in memory retrieval during early infancy. Three-month-old infants were trained to move a mobile by kicking. Two weeks later, memory retrieval was disrupted if they were reminded in a location or place different from where they had been trained, but not if they were reminded in the same place (Experiment 1A). The same result was obtained even though highly salient cues in their immediate visual surround remained unchanged during reminding (Experiments 1B and 1C). No disruption was seen, however, when retrieval was cued in a different place after only 1 day (Experiment 2). These findings unequivocally demonstrate that infants as young as 3 months encode incidental information about the place where an event occurs and suggest that early memories are buffered against retrieval in potentially inappropriate contexts over the long term.

Arousal↗
PubMed1991

Contextual variation and memory retrieval at six months.

In 2 experiments we asked whether training in multiple contexts could eliminate context-dependent memory retrieval at 6 months as it does for adults. We found that 24-hour retention was disrupted when infants were trained in one context and tested in another but not when they were trained in multiple contexts prior to testing in a novel context (Experiment 1). After a long delay, however, training in multiple contexts did not facilitate memory retrieval in a novel context: An otherwise effective retrieval cue (the training mobile) did not alleviate forgetting 3 weeks later when it was presented in a novel context (Experiment 2). These findings demonstrate that multiple learning contexts can override the debilitating effects of an altered context on memory retrieval at 6 months, but only over the short term. The resistance of older memories to retrieval in novel contexts after long periods of disuse may be adaptive, insuring that potentially inappropriate or irrelevant memories will not be expressed.

Attention↗
PubMed1990

Roles of function, reminding, and variability in categorization by 3-month-old infants.

The roles of function, reminding, and exemplar variability in categorization of a physically dissimilar object were studied with 3-month-old infants trained to move a crib mobile by kicking. Performance on a transfer test with a motionless novel object provided evidence of categorization. In Experiments 1 and 2, infants, like adults, initially categorized novel objects on the basis of physical appearance, but only if trained with multiple exemplars, after delays of 1 and 7 days. In Experiment 3, prior knowledge of an object's functional properties overrode physical dissimilarity as the basis for categorization and enabled reminding of the classification response 2 weeks later. In Experiment 4, postevent contingency information overrode physical and functional properties as the basis for categorization. These findings indicate that expectations and goals influence infants' category decisions and raise the possibility that infants of 3 months respond by analogy.

Arousal↗
PubMed1990

Contextual constraints on memory retrieval at six months.

In 3 experiments, 6-month-old infants learned to move a mobile by kicking and were tested 1 to 21 days later for retention of the newly acquired memory as a function of the training and testing contexts. In Experiment 1, decreasing the relative distinctiveness of the training and testing context did not impair retrieval of the newly acquired memory. In Experiment 2, however, testing in a different context completely eliminated retention after delays of 1 and 3 days, when retention was otherwise perfect; after progressively longer delays, retention improved paradoxically. The familiarity or novelty of the test context was not a factor in the failure of infants to recognize the mobile in the altered context after 1 day. In Experiment 3, the effect of an altered context was assessed in a reactivation paradigm. After the training memory was forgotten, infants were presented with the original mobile as a reminder and were tested for retention of the training memory 1 day later. When either the reminding context or the testing context was different, they exhibited no retention. These findings reveal that memory retrieval at 6 months is highly specific to the setting in which the memory is acquired. We propose that infants learn what specific events are associated with what specific places prior to the age when they can locomote independently and acquire a spatiotemporal map of the relations between those places.

Attention↗
PubMed1989

Amount of training and retention by infants.

In studies of animals and adult humans, more training typically leads to better retention. The generality of this finding was assessed in two studies with human infants in which amount of training was manipulated in two different ways. In the first study, 3-month-olds were trained for either 1, 2, or 3 sessions, each 9 min long; in the second, they were trained for a single session that was either 6, 9, 12, or 18 min long. Retention of independent groups was measured after delays ranging from 1 to 21 days. In both studies, different amounts of training did not yield group differences on any of the standard measures of acquisition or after a retention interval of 1 day. After intervals of a week or longer, however, more training led to better retention. Across studies, the long-term retention of groups that were trained for the same amount of time differed. We speculate that subjects learn different things in these two training regimens.

Arousal↗
PubMed1989

Contextual gating of memory retrieval.

In two experiments, 3-month-old infants learned to move a crib mobile (the cue) in the presence of a distinctive crib bumper (the context) by operant kicking. In Experiment 1A, infants were trained for 2 days and tested either 1, 3, or 5 days later with one of four same/different cue/context combinations. After all delays, infants tested with the original cue and context exhibited excellent retention, and those tested with a different cue and context exhibited none. Changing the context but not the cue disrupted retention after 3 and 5 days but not after 1 day; in contrast, changing the cue but not the context disrupted retention after all delays. In Experiment 1B, the failure of a contextual change to impair retention after 1 day was replicated. In Experiment 2, three same/different cue/context combinations were used as reminders in a reactivation paradigm, and all infants were tested 1 day later with their original training combination. A change in either the context or the cue significantly impaired the effectiveness of the reminder. These results reveal not only that contextual information is incorporated into the memory representations of very immature infants but also that memory retrieval is highly specific to the context in which an event was originally encoded. This specificity buffers against generalized memory retrieval after long retention intervals. The data are consistent with Reeves and Sperling's 1986 model of attention-gating. The context appears to serve as the initial gate for attention to potentially effective retrieval cues.

Analysis of Variance↗
PubMed1988

Continuities in infant memory development.

Fifty-five 6- to 7-month-old human infants were trained in an operant conditioning procedure, adapted from a procedure developed for 3-month-olds, in which kicks were reinforced by conjugate movement of a mobile. Retention was assessed in a simple forgetting paradigm (Expt. 1) or in a reactivation paradigm (Expt. 2) with either the training mobile or a different one serving as the retrieval cue. In Experiment 1, retention was tested 1, 7, 14, or 21 days after training. When the training and test mobiles were the same, infants exhibited virtually no forgetting for 14 days, but forgetting was complete by 21. When the training and test mobiles were different, infants exhibited no retention, discriminating the novel mobile for as long as they could remember the contingency. In Experiment 2, when the training mobile was presented as a reminder, the forgetting previously seen after 21 days was alleviated; when a different mobile was the reminder, it was not. These findings reveal that the efficacy of a reminder is predicted by the efficacy of that same stimulus in cuing the original memory 24 hr following training. Although the 6-month-olds learned more rapidly and remembered longer than infants half their age, their memory processing was described by the same basic principles.

Child Development↗
PubMed1987

Categorization and memory retrieval by three-month-olds.

84 3-month-olds were tested in 3 studies of the acquisition and long-term retention of category-specific information. Infants who were trained with a perceptibly different member of an alphanumeric category on each of 3 days generalized responding to a novel instance of the original training category but not a novel member of a novel category during a 24-hour novelty test. 2 weeks later, when infants displayed no evidence of remembering their prior training experience, categorization was reinstated if a novel exemplar from the original training category was used as the retrieval cue in a memory reactivation procedure. A novel exemplar from a novel category was not an effective retrieval cue. The effectiveness of the category-specific retrieval cue was a function of its physical similarity to the individual exemplars encountered during training, not testing. The background against which the alphanumeric exemplars were displayed during training was not an effective retrieval cue in either the 24-hour novelty test or the memory reactivation procedure, indicating that all invariant stimulus attributes do not contribute equally as category cues. These data are the first to document retention of category-specific information after extended intervals. A popular account of categorization holds that infants abstract invariant features from individual exemplars and form a schema or distinctive memory representation of these shared features against which subsequent exemplars are compared. The present data provide support for a more parsimonious account of categorization, based on the retrieval of information about individual exemplars, that does not require an assumption of prototype formation.

Arousal↗
PubMed1986

Ambient temperature effects on energetic relations in growing chicks.

The effects of different ambient temperature conditions on the diet selection, intake, growth, body temperature, and activity of immature domestic chicks were assessed in two experiments. In Experiment 1, the ambient temperature either remained warm during both the light and dark phases of the photoperiod, as is characteristic in laboratory settings, or was warm during the light phase and cold during the dark phase. The latter condition reflects the daily temperature pattern in natural settings. Chicks exposed to low nocturnal ambient temperatures had lower body temperatures in both phases of the photoperiod, were less active, ate more, selected a higher percentage of carbohydrate in their diets, and grew faster but were less feed-efficient than warm-reared controls. In Experiment 2, the ambient temperature was either cool in both phases of the photoperiod or cool in the light phase and warm in the dark phase. Chicks reared continuously in the cold had lower body temperatures, selected a high-carbohydrate diet, and grew faster, but both rearing groups were relatively inactive. These results show that an animal's body temperature, diet composition, food intake, feed efficiency, and activity reflect its 24-hr energy requirements and are a part of a general strategy of maximizing energy income and minimizing energy expenditure in response to energetic challenges to growth.

Animals↗