Search PubMed⌕ Search

Biomedical subjects

C Rovee-Collier

Publications and source records attributed to C Rovee-Collier.

At least 37 records · Page 2Linked to original sources
PubMed1997

Dissociations in infant memory: rethinking the development of implicit and explicit memory.

Extending the Jacksonian principle of the hierarchical development and dissolution of function to the development and dissolution of memory, researchers have concluded that implicit (procedural) memory is a primitive system, functional shortly after birth, that processes information automatically, whereas explicit (declarative) memory matures late in the 1st year and mediates the conscious recollection of a prior event. Support for a developmental hierarchy has only been inferred from the memory performance of adults with amnesia on priming and recognition-recall tests in response to manipulations of different independent variables. This article reviews evidence that very young infants exhibit memory dissociations like those exhibited by adults with normal memory on analogous memory tests in response to manipulations of the same independent variables. These data demonstrate that implicit and explicit memory follow the same developmental timetable and challenge the utility of conscious recollection as the defining characteristic of explicit memory.

Adult↗
PubMed1997

Infant learning and long-term memory at 6 months: a confirming analysis.

In three experiments, we tested the generality and validity of prior evidence of delayed recognition, memory reactivation, and retrieval specificity at 6 months of age using a new operant task. In Experiment 1, the forgetting function was found to be 2 weeks but not 3, the same as previously obtained using the mobile conjugate reinforcement task. In Experiment 2, a reactivation treatment with the original cue (train set) in the original context (room in the home) recovered the memory but was ineffective when either was changed. These results also confirmed prior findings but expanded the manipulation of context to include the place where training occurred. Following a reactivation treatment, infants in Experiment 3a failed to recognize the original cue in a different context, as before, but generalized to a different cue in the original context. Because the latter test condition was novel, a comparison group was trained in the mobile task and tested with a different mobile in the original context 1 day after a reactivation treatment (Experiment 3b); this group failed to recognize the mobile. The disparity in these outcomes was attributed to the salience of features common to the two train sets. Taken together, these findings demonstrate that, for the same parameters of training and testing, memory performance at 6 months is task-independent.

Association Learning↗
PubMed1997

Behavioral thermoregulation in chicks: the best nest.

The ability of prehomeothermic chicks to thermoregulate behaviorally was studied in chicks with continuous access to heated nests, running wheels, and separate sources of high and low protein. In Experiment 1, cold-reared groups with heated or unheated transparent nests ate the same amount and selected the same dietary fractions, but chicks with heated nests ran less and grew faster. Despite this, groups maintained normal body temperatures. In Experiment 2, chicks were cold- or warm-reared with heated or unheated painted nests, or no nests. Cold-reared chicks with heated nests spent most of their time in them. They selected diets containing a higher protein:carbohydrate ratio than cold-reared chicks with unheated nests but ate less, thereby consuming less absolute protein and growing more slowly. Despite differences in growth, intake, and dietary choice, all chicks maintained normal body temperatures. These data reveal that behavioral thermoregulation has a privileged status for chicks over the first 3 weeks of life. Prehomeothermic chicks exercise complex and effective solutions to energetic challenges when offered behavioral options that simulate those available in nature.

Adaptation, Psychological↗
PubMed1996

Diet selection by chicks.

Seven experiments with 324 chicks tested their ability to select a nutritionally adequate diet from separate sources of purified casein and various supplements, including gelatin (a source of two amino acids), a gelatin-creatine mixture (a source of three amino acids), and fiber (nonnutritive bulk). Nonselecting controls consumed the basal purified-casein diet or a supplemented purified-casein diet. Chicks in all selection conditions composed diets that yielded normal intake, normal body temperature, normal activity, and the maximum growth possible for their intake. They also selected components in the same percentages as in premixed diets. In all instances, their selection was nonrandom and regulated. What chicks included in their diet depended on what else was available. Although the specific percentage taken from each dietary component varied across different selection alternatives, these differences affected neither intake nor growth. Selection, per se, incurred a caloric cost. Chicks selecting from fractions of a corn-and-soy diet offset this cost by increasing intake compensatorily, but chicks with a purified-casein fraction did not, suggesting that some unspecified property of casein placed a ceiling on its intake. These findings unequivocally demonstrate that immature chicks not only can self-select nutritionally adequate diets, but can do so with unexpected precision by exploiting different but equally successful strategies.

Animal Nutritional Physiological Phenomena↗
PubMed1996

Learning and retention of conditioned aversions by freely feeding chicks.

The present experiments assessed poison-based aversion learning and retention in freely feeding and drinking domestic chicks whose drinking water was colored blue and adulterated with LiCl for a 24-hr period. The amount of LiCl self-administered by 11-day-old chicks and their subsequent avoidance of unadulterated water of the same color was examined. The results of four experiments demonstrated that chicks self-administered large and often lethal doses of the LiCl solution. Chicks subsequently avoided blue water during two-bottle preference tests administered 3 to 7 days but not 14 days after exposure. These data indicate that neophobia alone is insufficient to prevent nondeprived chicks from ingesting large quantities of a toxin during their initial encounter with it. The lack of long-term retention in the present experiments indicates that naturally occurring aversions based on visual and illness cues, while effective in the short term, may not be a major factor in the choices made by freely feeding and drinking chicks over the long term.

Animals↗
PubMed1996

The effect of repeated reactivations on memory specificity in infancy.

The cues that reactivate forgotten memories of young infants are highly specific. At the time of initial reminding, if either the cue or context differs from that originally present during encoding, then the memory is not recovered. In three experiments, we asked whether this specificity decreases over repeated reactivations. Three-month-old infants, trained in the mobile conjugate reinforcement paradigm with a particular cue in a particular context, received multiple reactivation treatments after their training memory was forgotten; either the cue or the context was changed during the final reminder. For a given age of the memory, context specificity was eliminated after fewer retrievals than cue specificity, and the number of retrievals required to eliminate specificity interacted with the age of the memory. These results confirm that different memory attributes become inaccessible at different rates and that repeatedly retrieved and older memories are likely to be less detailed. This transformation may underlie reconstructive memory in linguistic individuals.

Child Development↗
PubMed1996

Timing effects of postevent information on infant memory.

The role of the timing of postevent information on retention was assessed with 124 6-month-olds. In four experiments, infants learned to kick to move a particular crib mobile (the original target), were passively exposed to a discriminably different mobile (the postevent information), and were tested for recognition of the original mobile, the postevent-exposure mobile, or a completely novel mobile 24 h later. All interpolated exposures occurred after delays when infants' retention of the training mobile is excellent. In Experiment 1, the interpolated information precluded recognition of the training mobile (memory impairment) after all exposure delays. In Experiment 2, when the interpolated information was exposed within a week of training, infants treated the exposure mobile as if they had actually been trained with it (memory facilitation). Despite the recognition failures in Experiments 1-2, both original and exposure mobiles later reactivated the training memory, but only if the interpolated exposure was early in the retention interval; if it was later, only the exposure mobile was an effective reminder (Experiments 3A-3B). In Experiment 4, exposing postevent information after longer delays led infants to respond to a completely novel mobile (categorization). These findings demonstrate that postevent information has different qualitative effects depending on its timing and provides a basis for understanding discrepant reports of postevent-information effects with children and adults.

Exploratory Behavior↗
PubMed1996

Infants' memory for context: timing effects of postevent information.

How infants' memories of the context or place where an event occurred are selectively distorted was studied in 6-month-olds, who kicked to activate a mobile in a distinctive context for 2 days and then saw that mobile in a different context for 2 min either 1 or 6 days later. Infants whose exposure delay was 1 day failed to recognize the mobile in either the original or the exposed context but did so in a completely novel one. Infants whose exposure delay was 6 days--after the details of the original context were forgotten--recognized the mobile in the exposed context and no other, and the mobile could reactivate the forgotten memory only in the exposed context and no other. In effect, the details of the exposed context appeared to have been substituted in memory for the original details that had been forgotten. Thus, when components of an event are encountered later in a new context, that new context may be falsely remembered as being where the event had actually occurred, and the original context may be forgotten altogether. This error is more likely when a memory is older and may underlie some of the inaccuracies of childrens' and adults' recollections of their prior experiences.

Adult↗
PubMed1996

Set size, novelty, and visual pop-out in infancy.

The effects of set size and novelty on visual pop-out in 6-month-old infants was assessed in a perceptual-identification (memory reactivation) paradigm in which infants, trained and tested in their own homes, viewed a mobile containing a unique novel or familiar object amidst different numbers of familiar or novel distractors, respectively. Unique objects of both types popped out at all set sizes except the largest, where there was modest evidence that familiar distractors speeded processing (Experiment 1). When the proportion of familiar targets in a display of intermediate set size was increased, however, infants no longer detected the familiar target (Experiment 2). These findings offer additional support for the proposition that visual pop-out in infants and adults is the some phenomenon.

Adult↗
PubMed1996

Infants' forgetting of correlated attributes and object recognition.

Infants as young as 3 months of age can encode the relations among object features. Because object recognition depends critically upon a match between perceived feature configurations and representations of the object in long-term memory, the present experiments focused on infants' long-term memory for feature correlations. In 3 experiments with 72 3-month-olds, we documented the forgetting functions of different feature correlations, examined their relation to infants' memory for individual features, and replicated the findings with different stimuli. Infants were trained to activate a mobile composed of two kinds of blocks that differed in color, the figures displayed on them, and the figures' colors and were tested after different delays with recombinations of either the block colors, the figures, or the figure colors. Infants remembered some of the original feature combinations for up to 3 days but forgot all of them after 4 days. Even after 4 days, however, infants remembered the individual features that had entered into the original combinations. These results demonstrate that very young infants not only encode the relations among object features but also remember them for several days. Moreover, there is a dissociation in memory between features and feature relations: Feature relations are forgotten sooner than the individual features that comprise those relations.

Association Learning↗
PubMed1995

Developmental changes in the contextual control of recognition.

In three experiments, we explored potential developmental differences in the contextual control of target recognition using elementary perceptual features that differed only in their spatial relations. Three- and 6-month-old infants were trained in the presence of black horizontal and vertical line segments arranged as Ls, Ts, or +s on a pink background and were tested in the presence of the same line segments in a different spatial arrangement. At both ages, target recognition required a match between the primitive perceptual features in the test context and those present during training. Delayed recognition by younger but not older infants also required a match between specific spatial arrangements of the horizontal and vertical segments (+s versus Ls or Ts), despite the fact that infants of both ages had initially encoded these relations. These data suggest that by 6 months, spatial information in the periphery is detected preattentively via a parallel-processing mechanism, as it is in children and adults.

Age Factors↗
PubMed1995

Effects of postevent information on infants' memory for a central target.

In three experiments with 78 infants, we explored the effect of introducing novel information about a central target after a short delay on 6-month-olds' recognition of the original target, the novel exposure target, and a completely novel one. In all experiments, infants learned to move a particular crib mobile (the central target) by kicking and then were exposed to a novel mobile (the conflicting postevent information) immediately after training was over. In Experiment 1, memory for the original mobile was unimpaired, but infants treated both the exposure mobile and a completely novel one as if they had actually been present originally. In Experiment 2, only a completely novel mobile was an effective remainder in a reactivation paradigm, indicating that the impact of postevent information was relatively long-lasting and that the failure of the other mobiles to recover the training memory resulted from trace competition at the time of retrieval. In Experiment 3, identical novel information did not proactively affect recognition. Thus, 6-month-olds' memory of a central target is resistant to impairment by conflicting postevent information after a short delay, but they are highly prone to source misattribution. We propose that postevent information effects are cognitively efficient.

Association Learning↗
PubMed1995

The organization of reactivated memory in infancy.

The specificity of memory retrieval by 3-month-old infants was examined in 3 experiments. All infants were trained in the mobile conjugate reinforcement paradigm to kick their feet to produce movement in an overhead crib mobile and were tested 2 weeks later. 24 hours prior to the test, subjects received a 3-min reminder treatment. The results of Experiment 1 demonstrated that only the moving training mobile alleviated forgetting after the 2-week retention interval; forgetting was not alleviated by exposure to the stationary training mobile or to the mobile stands and ribbon alone. The results of Experiments 2 and 3 demonstrated that, once retrieved, the reactivated memory was highly specific to the conditions of original training. Furthermore, the memory attributes that were the last to be forgotten (e.g., the general or global features) were the first to be retrieved following the reminder treatment. Conversely, those memory attributes that were forgotten first (e.g., the specific or local details) were the last to be retrieved. These findings have important implications for infant memory retrieval, reminiscence, and infantile amnesia.

Child Development↗
PubMed1994

Contextual updating of infants' reactivated memories.

The ease with which a reactivated memory is updated has major implications for whether or not a prior memory is likely to be retrieved in the future. In three experiments, we explored this problem with nonverbal human infants, whose newly acquired memory of training in a specific context is readily updated by novel contextual information. In Experiment 1, exposing infants to a novel context immediately after a successful reactivation treatment neither impaired their retention in the original context nor facilitated it in the novel exposure one. In Experiment 2, increasing the delay between the reactivation treatment and exposure to the novel context also failed to facilitate retention in the novel test context. In Experiment 3, the reactivated memory was updated when the contingency was briefly experienced in the novel context immediately after the reactivation treatment. Under these circumstances, previously trained infants exhibited retention in the novel context, but infants who had not been trained 3 weeks earlier or whose original memory had not been reactivated exhibited none. The resistance of a reactivated memory to contextual updating unless the new context is predictive apparently buffers infants' memories against revision after long delays by contexts that could be inappropriate.

Attention↗
PubMed1994

Global and local processing of incidental information and memory retrieval at 6 months.

In five experiments, we examined the role of global and local cues in memory retrieval in infancy. Six-month-old infants were trained at home in a distinctive context (playpen liner) to kick to move a mobile. The liners were yellow and displayed either green stripes, green squares aligned vertically in stripe-like columns, or green squares in a grid pattern. The stripes and columns liners had a similar global configuration but different local components; the columns and grid liners had identical local components but different global configurations. When infants were tested 24 h after training in the presence of context liners that differed from the training context in either global configurations or local features, their memory retrieval was disrupted (Experiments 1 and 2). However, a change from stripes to columns failed to disrupt memory retrieval, even though the reverse change, from columns to stripes, did. Experiments 3, 4, and 5 revealed that this asymmetry was due to the fact that, when discriminative local information is not directly associated with training, a postperceptual strategy enables infants to disregard a mismatch in local information between training and test contexts and to generalize on the basis of a match in global information during the 24-h retention test. Thus, infants encode and remember for substantial periods of time both global configuration information and local component information in the incidental context in which an event occurs and flexibly utilize this information when responding to new events.

Color Perception↗
PubMed1994

The memorability and discriminability of primitive perceptual units in infancy.

Three-month-olds were operantly trained to kick to move a block mobile that displayed a horizontal and a vertical line ("textons") arranged as L, T, or + on each side. Delayed recognition was tested either 0, 1, 3, 5, 7, or 9 days later with either the same or a different display. Infants failed to discriminate between Ls and Ts after delays longer than 1 hr but discriminated both from +s, which contains an additional texton (the line crossing), after delays as long as 7 days but not 9. Also, they remembered +s longer than Ls and Ts. These data indicate that the same primitive perceptual units that mediate adult texture segregation are differentially discriminated and differentially memorable in early infancy.

Discrimination, Psychological↗
PubMed1994

Substituting new details for old? Effects of delaying postevent information on infant memory.

How that which we remember is selectively distorted by new information was studied in 3-month-old infants who learned to move a particular crib mobile by operant foot kicking. Infants who were passively exposed to a novel mobile 1, 2, or 3 days later subsequently treated the novel mobile as if they had actually been trained with it. Also, after the longest exposure delay, they no longer recognized the original mobile. Likewise, when the novel mobile was exposed after the longest delay, it could prime the forgotten training memory in a reactivation paradigm, but the original mobile no longer could. These data reveal that what we remember about an event is selectively distorted by what we encounter later. Moreover, the later in the retention interval we encounter new postevent information, the greater is its impact on retention.

Child Development↗