Permanent Task Research Articles

4.2. Intertemporal capacity expansion models

Planning must be seen as a permanent task. And, with respect to the practical application of the optimal results, as the actually interesting outcome of the planning process, the near future transition from the system presently existing to the system of the future is revealing. Intertemporal models-in connection with linear programming; i.e., multi-period models-facilitate the consistent assessment of both the long-term ideal system and the near future system representing the first step to the ideal system according to an objective pursued.

Behavioral effects of developmental lead exposure in rhesus monkeys.

Postnatal lead exposure has been found to cause long-term learning and memory deficits in monkeys. Pulse-chronic exposure, consisting of acute high-level exposure followed by chronic lower-level exposure, has been particularly effective in causing these impairments. We investigated possible antecedents of lead-induced cognitive dysfunction by evaluating the behavioral effects of pulse-chronic lead exposure in rhesus monkeys during the first 6 months of postnatal life. Blood lead concentrations in the monkeys reached a peak of 55.8 +/- 7.8 ug/dl during week 5 after birth and then averaged between 33.1 and 42.9 ug/dl during the rest of the first 6 months after birth. Zinc protoporphyrin levels were increased by lead exposure, but hematocrits were unaffected. Significant lead-related effects were detected on a visual exploration test and a neonatal behavioral assessment battery. Lead-treated monkeys exhibited decreased looking behavior on the visual exploration test and decreased muscle tonus and increased arousal or agitation on the behavioral assessment battery. No effects were seen on a Piagetian object permanence task and no toxic effects on health or growth were detected. In addition to providing indices of behavioral dysfunction during postnatal lead exposure, performance on these early behavioral tests may predict later lead-induced cognitive dysfunction.

Accelerated development of object permanence in Down's syndrome infants.

Six infants with Down's syndrome, aged 3-19 months, were taught to solve object permanence problems. The instruction took place in the infants' homes and in a child development centre, and was conducted both by parents and by a child psychologist. Object permanence tasks ranging over stages 3-6 of the sensorimotor period of intelligence were utilized in the intervention, which lasted for up to 8 months. The infants were able to progress rather rapidly on these tasks. When the instruction was terminated most had mastered multiple visible displacements, which index the fifth stage of sensorimotor intelligence.

Object permanence and relational words: a lexical training study.

ABSTRACTObservational/correlational research has established that children in stage 5 object permanence development use words that refer to the visible movement of objects, while it is not until stage 6 that they use words referring to the invisible movement of objects (e.g. gone). It is not clear, however, whether the cognitive competence evidenced by performance in the object permanence task is a prerequisite for these linguistic productions or whether they both emerge simultaneously from some underlying representation. The current study used a lexical training paradigm to teach object words, visible movement words, and invisible movement words to children at stage 5 and stage 6 object permanence development. Stage 6 children learned all three types of words equally well. Stage 5 children learned object and visible movement words, especially in comprehension, but did not learn the invisible movement word. These results indicate that the cognitive structures underlying performance in the object permanence task are genuine prerequisites for learning these types of words.

The role of attentiveness, mobility history, and separation of hiding sites on stage IV search behavior

The relationship between visual attentiveness, search behavior, and duration of independent mobility was examined for fifty-six 8- to 10-month-old infants presented with three versions of the Stage IV object permanence task. The number and spatial separation of hiding sites was manipulated to explore the role of these factors on visual attention and search performance. In a repeated measures design, perseverative search errors were less likely on both a two- and a six-location task with equally wide separation of the A and B hiding sites than on a two-location task with A and B close together, thus indicating that spatial separation of sites is a more important contributor to successful search than number of hiding sites alone. In addition, visual attentiveness was significantly associated with correct search at B in all three versions of the task. A significant developmental relationship was found between the length of time infants had been independently mobile and visual attentiveness during the hiding procedure. These findings are discussed in terms of the transition to self-produced mobility and expanding spatial experience in the second half of the first year and how visual attentiveness and search performance might improve as a function of such changes.

Development of the Ability to Use Recall to Guide Action, as Indicated by Infants' Performance on AB

25 infants were tested every 2 weeks on the AB Object Permanence Task devised by Piaget, from the age when they first reached for a hidden object until they were 12 months. The delay between hiding and retrieval necessary to produce the AB error increased continuously throughout this period at an average rate of 2 sec/month, from under 2 sec at 7 1/2 months to over 10 sec by 12 months. All children displayed the AB error repeatedly over the months of testing. Large between-children differences in delay needed for the AB error were found at each age. Girls tolerated longer delays than boys. The characteristic pattern to the AB error did not vary over age or sex. Range of delay producing the AB error in any child was small. Errors disappeared when delays were reduced by 2-3 sec, and reaching became random or severely perseverative when delays were increased 2-3 sec above the level producing AB error. AB provides an index of the ability to carry out an intention based on stored information despite a conflicting habitual tendency.

Self-recognition in autistic children.

The hypothesis that the autistic child's impairment in social relatedness stems in part from underlying deficits in self-recognition was explored. Fifteen autistic children ranging from 4 to 6 years of age were assessed for visual self-recognition ability, as well as for skills in two cognitive areas that are believed to be related to the development of self-recognition--object permanence and gestural imitation. It was found that 13 of 15 autistic children showed evidence of self-recognition. The two autistic children who lacked self-recognition were the only two children to perform poorly on the object permanence tasks, which suggests that these two cognitive domains may be closely linked in development. In contrast, there appeared to be no consistent relationship between motor imitation ability and self-recognition. It was concluded that the autistic child's social deficits are not due to a basic lack of differentiation between self and other.

Visual tracking and anticipation in a permanent object task in 4 to 9 month old infants

Visual tracking and anticipation in a permanent object task in 4 to 9 month old infants

The Development of Detour Ability during Infancy

3 longitudinal studies were conducted to examine the generalization of detour ability across motor responses and barrier types and the relationship between the development of object permanence and detour ability. In Experiment 1, 12 8-month-olds were tested every 3 weeks for 4 months on 4 different detour problems and Stage 4 and 6 object permanence tasks. In the detour problems, infants had to reach or move around a transparent or opaque barrier to obtain an object. The results indicated that infants made reaching detours before corresponding locomotor ones and generally made detours around opaque barriers before transparent ones. Infants also solved the Stage 4 task before the detour problems but failed to solve the Stage 6 task before testing ended. The results of Experiments 2 and 3 suggested that the difference in reaching and locomotor detour performance was not an artifact of barrier length or the infant's position relative to the barrier. The overall results are discussed in relation to issues of developmental synchrony and Piaget's theory of infant spatial development.

The role of cup orientation in object permanence tasks

The role of cup orientation in object permanence tasks

Selective information use and perseveration in the search behavior of infants and young children

Two experiments examined the early development of selective information use in search. The first experiment tested 9- and 16-month-olds on a modification of Piaget's Stage IV object permanence task. It examined infants' use of information from previous experiences with an object (prior information) and from the most recent hiding (current information) to locate a hidden object. In the second experiment, 2-, 2 1 2 -, and 4-year-old children received these same sources of information along with new forms of prior and current information: information about the typical locations of objects (location specificity) and verbal information. No systematic perseveration was observed at 9 months, although previous findings related to perseveration were replicated. Perseveration was found at 16 months, but there was also evidence of selectivity at that age. When errors occurred, they tended to be to the prior location, but they were infrequent in comparison to correct searches at the current location. The preschoolers, while continuing to show perseveration, were more consistently selective than the infants. They also showed considerable generality in extending their selectivity to new sources of information.

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

Characteristics of hiding places and the transition to Stage IV performance in object permanence tasks.

The effects of cue distinctiveness on infants' manual search

Nine- and sixteen-month-old infants were repeatedly presented a manual search problem in which a toy was hidden in one of two containers, which were then moved into reach. The distinctiveness of the containers or their closeness during the movement was varied in different conditions. Overall, the older infants performed better than younger infants, performance improved across trials, and there were more correct searches when the containers or trajectories were distinctive. Analyses of visual orienting indicated that infants learned to restrict their looking to the hiding place. The ability to maintain attention to discriminative cues may be instrumental to progress in delayed-reaction and object permanence tasks.

Division of labor among workers ofPolistes metricus (Hymenoptera: Vespidae): Laboratory foraging activities

Division of labor in foraging activities of workers was studied in laboratory colonies ofPolistes metricus. Individual foraging activity was strongly affected by the foraging activities of nestmates. Usually the oldest worker of a colony became the principal forager. Other workers, in the presence of an active forager, did relatively little foraging regardless of age. Relatively inactive workers showed increased foraging rates when the older, active foragers were either removed or became less active with age, or when colony needs were greater (as evidenced by a marked rise in larval numbers). There was no temporal change in distribution of foraging tasks. The only indication of permanent task specialization was for paper collecting. All workers foraged for prey, water and honey but collection of paper was confined almost exclusively to the oldest workers of the colony.

Aspects of the Rational Evaluation of Numerically Controlled Machines for Their Effective Utilization

Publisher Summary This chapter analyzes various aspects of the rational evaluation of numerically controlled machines for their effective utilization. The problem of the evaluation of instruments of production results mainly from two fields of activity: (1) for determining a suitable structure of equipment for a given spectrum of parts, and (2) in an existing production, for the assortments of parts to be newly integrated with an existing stock of machines, there results the permanent task to guarantee the coordination according to production-technological and economic criteria. In each case, the aim consists of contributing to decision finding efficiently with as clear-cut criteria and calculation methods as possible. For the group of problems mentioned first, higher expenditure is required and justified in connection with fundamental decisions concerning the structure of equipment to be defined by these criteria. In principle, however, the same reflections and decision steps can be used for the coordination of parts. In this chapter, a few main problems connected with the production-technological preparation of the employment of numerically controlled production equipment are discussed.

Infant search tasks reveal early concepts of containment and canonical usage of objects

It is difficult to gain unambiguous evidence on the use of concepts by infants. Many results can be accounted for in terms of action-based strategies. The evidence reported here fulfils the minimal criteria for the operation of working concepts in infants. Search tasks are used with a filled interval which forces memory-search, and the object is hidden in containers which fulfil their customary job or violate it. Infants treat an upright cup as a more reliable location marker than an inverted one. A series of experiments probes the phenomenon. The results indicate that the infants have a working concept of containment which can be triggered by the provision of containers in their canonical orientation. Even “object permanence tasks” lead infants to access their knowledge of the relationships into which things typically enter in the world outside the laboratory.

Visual tracking in young infants: Evidence for object identity or object permanence?

Previous research has shown that 5-month-old infants visually anticipate a moving object's appearance after it disappears behind a screen. This experiment assesses the underlying basis for such anticipatory tracking. Three tracking tasks were presented to 5- and 9-month-old infants. In the Permanence task, the object's continuous existence was apparently violated while it was behind a screen. In the Feature and Trajectory tasks, the object's features or trajectory changed while behind the screen. Disruptions in the infant's smooth visual pursuit of the object were recorded. Five-mont-olds showed disruptions of visual tracking in the Feature and Trajectory tasks, but not in the Permanence task. The tracking of the 9-month-olds was disrupted in all three tasks. We conclude that both 5- and 9-month-olds possess rules specifying the identity of a moving object which is occluded. For 5-month-olds these rules are based upon the object's features and trajectory, but not upon a concept of object permanence. For 9-month-olds all three rules—feature, trajectory, and permanence—are utilized in visual tracking.

Expression of Owner-Owned Relationships among Holophrastic 14- to 32-Month-Old Children

RODGON, MARIS MONITZ, and RASHMAN, SUE E. Expression of Owner-Owned Relationships among Holophrastic 14to 32-Month-Old Children. CHILD DEVELOPMENT, 1976, 47, 1219-1222. 24 children age 14 to 32 months were shown a series of photographs of familiar and unfamiliar objects and persons in order to determine the frequency of owner naming and other expressions of possession. Only 7 subjects correctly named the owner of a pictured familiar object. Owner naming occurred mainly in response to pictures of the child's parent's possessions. 'Other indicators of possession were used, but by different children or in different situations. Children who used any indicator of possession were more successful on an object permanence task than were those who did not. Object naming was a much more frequent phenomenon than owner naming, but owner namers tended not to name objects whose owners were unknown to them.

Toward a Politics of Signs: Reading Baudrillard

Abstract The difficulties involved in defining a sign non-linguistically are well-known. Signal, indication, icon, symbol, allegory, terms which border on similarity and dissimilarilty, compete to attain the fleeing reality of the sign, which seems to exist only to abolish itself in its relational function and forgets its materiality. Whatever its basic nature, the sign is above all a mediating element, and, in the subject-sign-object triad, it is the sign that unifies the subject and object, while sanctioning their separation: the double function of mediation, the necessary intermediary, it destroys the problematic of intentionality in the strict sense. The multiplication of signs brings about the explosion of this elementary triad and allows the former to appear cutting across multiple networks which accomplishes a permanent task of absorption, the retention and retransmission of meaning and cummunication: intermundane space in the form of illusion of which the lack of being seems to be balanced by a surplus of meaning.