Social feeding reverses learned flavor aversions in spotted hyenas (Crocuta crocuta).

Spotted hyenas are highly social carnivores with competitive feeding habits. It was hypothesized that social feeding might be capable of reversing an established flavor aversion. The dominant hyena of each of 4 captive social groups was given a novel food mixed with LiCl on Day 1; aversion to this food was demonstrated on Day 2. On Day 3, the dominant hyena and 3 or 4 members of her group were offered the food simultaneously. Three of the 4 dominant hyenas ate substantial quantities of the food during this group feeding, and all 4 hyenas ate the following day when offered the food alone. In contrast, when averted to a different novel food, the hyenas refused that food on 3 consecutive days. In this species social factors, such as those operating during group feeding, are sufficiently powerful to attenuate, immediately and dramatically, a strong LiCl-induced aversion.     

Responses to olfactory stimuli in spotted hyenas (Crocuta crocuta): II. Discrimination of conspecific scent

Scent marking in spotted hyenas (Crocuta crocuta) includes the deposition of anal sac secretions, or "paste," and presumably advertises territorial ownership. To test whether captive hyenas classify and discriminate individuals using odor cues in paste, the authors conducted behavioral discrimination bioassays and recorded hyena investigation of paste extracted from various conspecific donors. In Experiment 1, subjects directed most investigative behavior toward scents from unfamiliar hyenas and members of the opposite sex. In Experiment 2, male hyenas discriminated between concurrent presentations of paste from various unfamiliar females in similar reproductive states. Thus, pasted scent marks convey information about the sex, familiarity, and even identity of conspecifics. Aside from territory maintenance, scent marking may also communicate information about individual sexual status.     

Responses to olfactory stimuli in spotted hyenas (Crocuta crocuta): I. Investigation of environmental odors and the function of rolling

Olfaction is crucial to spotted hyenas (Crocuta crocuta), yet there are no controlled studies of their reactions to odors. In Experiment 1, the authors examined responses of captive hyenas to various environmental (prey, nonprey animal, and plant) odors. Subjects approached and sniffed all odors equally but preferentially licked prey odors, scent marked next to odors, and rolled in animal-based odors. In Experiment 2, the authors examined the function of rolling by applying odors to the pelts of captive hyenas. When hyenas wore carrion, they gained positive social attention (increased investigation and allogrooming) from pen mates, but when they wore camphor, the normal social greeting ceremony was curtailed. Thus, olfactory stimuli elicit specific responses, influence where behavior is directed, and can be used to affect social interaction.     

Scent marking by male dwarf hamsters (Phodopus sungorus campbelli) in response to conspecific odors

Male hamsters (Phodopus sungorus campbelli) scent marked at greater frequencies in the presence of conspecific odor, either male or female, than in clean areas. Marking rates were not different between male and female odor conditions. In contrast, the pattern of investigation in response to conspecific odor did differ between the male and the female odor conditions. When male odors were used as stimuli, investigative sniffing increased at the scent marking sites but when female odors were used as stimuli investigative sniffing increased throughout the arena. Thus, male dwarf hamsters direct their scent marks at both male and female conspecifics, discriminate between male and female odor, and investigate in a different manner areas scent marked by males and females.     

Mechanisms of attention: a developmental study

A model of selective attention is proposed which contains a number of properties. First, stimuli which are irrelevant to the subjects' task can be analyzed to semantic levels automatically, and such stimuli can produce intrusion/interference effects. Second, two mechanisms by which selection is achieved are habituation to, and inhibition of, these irrelevant stimuli. A series of studies demonstrates that both the ability to process automatically irrelevant stimuli and the habituation mechanisms of attention are observable by Grade 2, whereas the inhibitory mechanism is not always evident at this stage. It is suggested that the greater distractability of children in certain situations may be due in part to the underutilization of this inhibitory mechanism. We further propose that children may be able to employ inhibitory mechanisms in more familiar perceptual-motor tasks.     

Cognitive factors in simple reactions: a developmental study

In an exploration of factors underlying the developmental increase in the speed of simple reaction to an auditory stimulus, two experiments were undertaken, with subjects aged 4, 10, and 20. The first experiment demonstrated that provision of visual feedback caused improvement for younger subjects but not for adults, whereas neither practice nor variable feedback caused any differential change. The second experiment was a simulated game where visual feedback was contingent on a "hit" on the previous trial. Following a hit the target moved faster, following a miss, slower. Practice caused a considerable improvement for the 4-year old subjects, but not for the older subjects. The nature it or miss feedback on the previous trial had powerful effects on the simple reaction times. For all subjects, a miss resulted in a subsequent substantial increase in speed on the next trial. Following a hit, the adults were unaffected, but the youngest subjects were substantially slower. The results are interpreted in terms of inappropriate relaxation following a hit for the 4-year old subjects, with active strategic behavior by the adults, following a miss. It is concluded that one variable (incentive provided by a miss) affects simple reaction for all ages, that two (disincentive provided by a hit, and visual feedback) differentially affect subjects of different ages, and that a fourth (use of a "trade-off" strategy) is not available to the youngest subjects.     

fMRI of developmental stuttering: a pilot study

The purpose of this investigation was to explore the feasibility of fMRI in the study of developmental stuttering. Speech contrasts (loud versus silent reading) and language contrasts (reading of semantically meaningful text versus nonsense words) of six developmental stutterers and six nonstutterers were compared using a commercial 1 Tesla MR-Scanner (Siemens Expert). Results indicate that mapping cortical function in persons who stutter is indeed feasible, even with a 1TMR-system. Compared to normals the stutterers seemed to employ different and particularly less differentiated auditory and motor feedback strategies in speech. They apparently rely on auditory processing and on cerebellar contribution as much during silent reading as during reading aloud. Moreover, they showed a greater involvement of the right hemisphere in language processing, activating not only the typical language areas on the left but also and with equal magnitude the right side homologues of these areas. In spite of the promising results, at present several practical problems such as possible movement artifacts and possible masking through scanner noise still hamper a more straightforward use of fMRI in the study of developmental stuttering.     

A developmental study of the Prelinguistic Auditory Store (PAS)

Lists of digits 5 and 7 items in length were presented to second graders, sixth graders, and low-IQ sixth graders in either the visual or auditory modality. Half the auditory lists were followed by the redundant nonrecalled, auditorily presented word “recall” which served as a list suffix. The second graders had the most errors in the ordered recall task followed by the low-IQ sixth- and normal sixth-graders in that order. The size of the modality and suffix effects for the various groups seemed to indicate that, for the younger subjects, a larger proportion of the recall after auditory presentation comes from the Prelinguistic Auditory Store than for the older subjects.     

Movement control in a reciprocal tapping task: a developmental study

A cross-sectional approach was used to replicate and examine developmental flexibility in eye-hand relationships during alternate tapping performance. A group of 68 male subjects, 34 younger (mean 75.6 months) and 34 older (mean 128.9 months) practiced 12 5-sec trials of alternate tapping in one of three accuracy conditions. Trials 2 and 11 were filmed to determine the eye movement index (EMI), a fraction relating eye movements (numerator) to alternate taps (denominator). Fractional EMI values close to 1 were labelled discontinuity and values closer to 0 (1/N) continuity. Accuracy variation tested the flexibility of EMI for developmental change, revealing that EMIs for older subjects were more continuous than for younger subjects at trial 11, but not at trial 2. Level of EMI was related to age and condition, while change in EMI due to practice was related to age. The data showed EMI strategy flexibility increased with age, and that faster tapping was afforded by less direct visual monitoring of the hand.     

Syntactics of interpretation of negation: a developmental study

Two cues are considered as syntactic indicators of the focus of a sentential negation in 7- and 10-year-olds and adults. One is the articles; it is proposed that an indefinite noun phrase is taken within the scope of a negative and a definite noun phrase outside it. A second cue is position. Based on R. S. Jackendoff's (1969, Foundations of Language, 5, 218-241) and P. A. Hornby's (1971, Child Development, 42, 1975-1988) work, subjects may be expected to take the second noun within the focus of sentential negatives regardless of the articles. In Experiments 1 and 2, subjects made picture selections for sentences of the form A/the Noun1 isn't V-ing the/a Noun2 and their passives. In Experiment 3, 10-year-olds describe the scenes of the sentences of the prior experiments. Noun position and article independently influenced the focus of the negation with age trends. Developmental differences in the uses of the articles are related to the acquisition of mastery of these linguistic markers.     

Toward a developmental psychology of Sehnsucht (life longings): the optimal (utopian) life

The topic of an optimal or utopian life has received much attention across the humanities and the arts but not in psychology. The German concept of Sehnsucht captures individual and collective thoughts and feelings about one's optimal or utopian life. Sehnsucht (life longings; LLs) is defined as an intense desire for alternative states and realizations of life. Presenting a first effort at capturing this phenomenon, the authors conceptualize LLs as composed of 6 interrelated core characteristics: (a) utopian conceptions of ideal development; (b) sense of incompleteness and imperfection of life; (c) conjoint time focus on the past, present, and future; (d) ambivalent (bittersweet) emotions; (e) reflection and evaluation of one's life; and (f) symbolic richness. Self-report data from 299 adults (19-81 years) support the postulated structure and support predictions regarding the functional role of Sehnsucht. Having LLs was evaluated as providing direction to development and helping to manage life's incompleteness. At the same time, the frequent and intense experience of LLs was associated with lower well-being. When LLs were perceived as controllable, however, this negative association disappeared.     

Working memory: a developmental study of phonological recoding

A cross-sectional study using children aged 3 to 7 years and a cross-sequential study using children aged between 5 and 8 years showed that the development of phonological recoding in working memory was more complex than the simple dichotomous picture portrayed in the current literature. It appears that initially children use no strategy in recall, which is proposed to represent the level of automatic activation of representations in long-term memory and the storage capacity of the central executive. This is followed by a period in which a visual strategy prevails, followed by a period of dual visual-verbal coding before the adult-like strategy of verbal coding finally emerges. The results are discussed in terms of three working memory models (Baddeley, 1990; Engle, 1996; Logie, 1996) where strategy use is seen as the development of attentional processes and phonological recoding as the development of inhibitory mechanisms in the central executive to suppress the habitual response set of visual coding.     

Towards a broader scope of biomechanics in developmental studies: a commentary on Jensen (2005)

In this article, we discuss where biomechanical analysis can contribute to our understanding of motor development, and more particularly in what ways biomechanics can contribute to (1) explaining the universal sequence in motor milestones; (2) explaining variations in developmental sequence between individuals; (3) understanding the impact of context on the actions of an individual; and (4) understanding, preventing, and managing chronic disabilities. In our view, biomechanics is concerned with the dynamics of the musculo‐skeletal system (MSS) and thus provides insights in the way motion is affected by the activation of muscles and the mechanical interaction between the MSS and the environment. Biomechanical analysis is important in understanding the development of actions that depend on the perceptual‐motor loop although it cannot provide a full account of the changes in the behaviour. The contributions and limitations of specific biomechanical analyses such as the inverse and forward dynamical models are discussed in the light of the article of Jensen (2005). Copyright © 2005 John Wiley & Sons, Ltd.     

Exploring relational regulation in computer-mediated (collaborative) learning interaction: a developmental perspective.

This article presents a qualitative analysis showing the dependency of effective collaborative argumentation on interpersonal relational aspects that develop during synchronous interaction. Four regulatory principles are proposed as propelling the interaction, and of these, autoregulation, or the conservative restraints within the existing relation, appears to be the dominant force. When using a structured dialogue system (SDS), instead of free chat, via roles and sentence-openers, the social dimension of the relation between participants disappears from the surface interaction. Even though using the SDS seems to foster a more focused and task-functional approach, argumentation appears to affect the relations between participants in a negative way, since after an argumentative sequence, repair of the relationship takes place. It might even be argued that, because of relational stress, in many cases, argumentation is momentarily suspended.     

Listening to distraction: a developmental study of selective attention

One hundred eight children 8, 11, and 14 years old selected one auditory message from two (male-female voice cue). Retention of target and distracting words was tested. Fifty-four control Ss heard the target message alone. Contrary to some earlier studies, distraction hindered the target performance of younger children more than older children. In the experimental groups target retention increased linearly with age but distraction retention remained constant. Intrusions from the distracting message during the selection task decreased greatly with increasing age. These and other results were interpreted as showing that the superior selective listening performance of older children is due not to a greater ability to filter out distracting material at an early stage of processing, but in large part to an ability to inhibit intrusions from the distracting material during the selection task.     

The role of within-category variability in category-based induction: a developmental study

The present studies tested the hypothesis that strong assumptions about within-category homogeneity impede children's recognition of the inductive value of diverse samples of evidence. In Study 1a, children (7-year-olds) and adults were randomly assigned to receive a prime emphasizing within-category variability, a prime emphasizing within-category similarities, or to not receive a prime. Only following the variability prime, children demonstrated a reliable preference for evaluating diverse over nondiverse samples to determine whether there is support for a category-wide generalization. Adults demonstrated a robust preference for diverse samples in all conditions. These effects extended beyond the specific categories included in the prime, as well as to multiple types of test questions. Study 1b demonstrated that priming variability leads children to select diverse samples only when doing so is informative for induction. Implications for conceptual development are discussed.     

Lying in the name of the collective good: a developmental study

The present study examined the developmental origin of 'blue lies', a pervasive form of lying in the adult world that is told purportedly to benefit a collective. Seven, 9-, and 11-year-old Chinese children were surreptitiously placed in a real-life situation where they decided whether to lie to conceal their group's cheating behavior. Children were also assessed in terms of their willingness in hypothetical situations to endorse lying or truth-telling that benefits a collective but at the same time harms an individual. Results showed that as age increased, children became more inclined to endorse lying in the name of the collective good, and to tell lies for their group themselves. Furthermore, children's endorsement about blue lies in hypothetical situations predicted their actual lying behavior.     

Kinematics of aiming in direction and amplitude: a developmental study.

The patterns of aimed movements to visual targets were analyzed in children aged 6, 8 and 10. Tasks with direction and/or amplitude requirements were used. The tasks were performed both with and without vision. Peak velocity, acceleration and deceleration and their relative temporal occurrence were evaluated. Overall, the 6- and 10-year-olds exhibited higher peak velocity and acceleration when performing the pure directional task than when performing tasks with an amplitude or stopping requirement. On the contrary, 8-year-olds showed similar peak acceleration and velocity across all three tasks. Similarly, when performing the pure directional task, the 6- and 10-year-olds reached their peak velocity and acceleration relatively later in time than the 8-year-olds. Vision of movement increased the peak velocity in all experimental tasks and peak acceleration was increased only in the pure directional task. Thus, movement kinematics varied according to the task requirements and age. Eight-year-olds showed greater propensity to feedback control in all tasks, suggesting an over-inhibition in their approach patterns, whereas 10-year-olds tended to use feedforward processes, with a shortened deceleration phase.