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PubMed1993

Patients' attitudes toward hallucinations.

OBJECTIVE: This study examined patients' attitudes toward their hallucinations by assessing their beliefs about the purposes served by hallucinations and the adverse effects of hallucinations. It also investigated whether these attitudes were related to characteristics of the hallucinations or of the patients, whether the attitudes changed after treatment, and whether attitudes before treatment predicted the presence or absence of hallucinations after treatment. METHOD: Fifty hallucinating psychiatric inpatients were given semistructured interviews shortly after admission to the hospital and again shortly before discharge. The interviews elicited detailed descriptions of 12 phenomenologic characteristics of hallucinations and 11 attitude variables. RESULTS: The majority of subjects reported some positive effects of hallucinations. The presence of olfactory hallucinations and the ability to predict hallucinations were significantly related to valuing hallucinations. Attitudes usually did not change with treatment; when they did change they usually became more positive. Subjects who valued hallucinations more before treatment were significantly more likely to be hallucinating after treatment. CONCLUSIONS: The findings are consistent with the idea that psychological factors contribute to the expression of hallucinations. Assessing adaptive functions of hallucinations may predict whether hallucinations will respond to treatment and identify fruitful areas for psychosocial intervention.

Adolescent↗
PubMed1982

A model for assessing potential adaptation to stress.

The purposes of this study were to determine if hospitalized medical-surgical patients could be classified reliably according to their potential to adapt to stress; and to explore the relationship between their adaptive potential and length of hospital stay. Forty-six patients were selected for participation by use of a table of random numbers. Three classes of significantly different adaptive potential were identified: the Alarm and Impoverished states were considered as stress states, while the state of Equilibrium was considered a nonstress state. Although it was possible to distinguish stress from nonstress states, using only physiological parameters, psychological parameters were required to distinguish between the two stress states. The differentiation among the three coping states was used to predict subjects' potential for mobilizing adaptive resources. Length of hospitalization was then related to classification of adaptive potential.

Adaptation, Psychological↗
PubMed2003

Ergodic and non-ergodic phase transitions in globular protein suspensions.

The equilibrium and nonequilibrium phase behavior of a protein suspension is investigated as a function of strength of interparticle attraction and protein concentration. The equilibrium phase behavior suggests that the range of the particle attractions is a small fraction of their diameter. At volume fractions and strengths of attractions smaller than those characterizing the spinodal of a metastable fluid-fluid transition, the suspensions gel before they crystallize. At higher volume fractions and lower strengths of attraction, gels are formed first from which crystals nucleate over a period of time. However, at higher strength of attraction, crystals form first at lower volume fractions while gels are observed at higher volume fractions. We hypothesize that this behavior results from the competition between the rates of gelation and crystal nucleation. The location of the gel line is well predicted by mode coupling theories adapted for low volume fractions and square well fluids. At low strength of attraction, the gel line occurs at small supersaturations suggesting gels will be seen before nucleation. However, at higher strengths of attraction the gel line occurs at greatly increased supersaturations such that crystal nucleation can occur before the gel line is crossed. That mode coupling theories should predict gelation when crystallization does not intervene is tested by investigating the gel dynamics.

Algorithms↗
PubMed1998

An energy dissipation-based model for damage stimulated bone adaptation.

Based on experimental observations, several researchers have proposed a role for damage processes in stimulating an adaptive response in bone. In the current study we propose a model for bone adaptation based on cyclic energy dissipation as a measure of bone damage creation. By reanalyzing the fatigue data of Pattin et al. (1996), we derive a uniaxial form of the damage based formulation applicable to cortical regions experiencing primarily longitudinal stresses. Because of the experimentally observed difference between damage formation under tension and compression (Pattin et al., 1996), this formulation naturally predicts a difference in the adaptive response to tensile and compressive loading. This feature distinguishes the new formulation from existing strain energy based adaptation theories which treat tensile and compressive strains identically. Thus, developmental adaptation in response to unequal generation of damage provides one possible explanation for the experimentally observed difference between peak tensile and compressive bone surface strains.

Adaptation, Physiological↗
PubMed2005

What's in a name? A comparison of methods for classifying predominant type of maltreatment.

OBJECTIVE: The primary aim of the study was to identify a classification scheme, for determining the predominant type of maltreatment in a child's history that best predicts differences in developmental outcomes. METHOD: Three different predominant type classification schemes were examined in a sample of 519 children with a history of alleged maltreatment. Cases were classified into predominant maltreatment types according to three different schemes: Hierarchical regression analyses examined whether the HT, SFT, and EHT type classifications contributed to prediction of child behavior problems, trauma symptoms and adaptive functioning. RESULTS: After controlling for demographic factors, the HT definitions predicted four outcomes, while the SFT definitions predicted three, and the EHT classifications contributed to the prediction of five child outcomes. The co-occurrence of multiple types of maltreatment was robustly related to outcomes. However, the HT and SFT classifications predicted outcomes even after accounting for the co-occurrence of multiple maltreatment subtypes. CONCLUSION: A classification scheme that differentiates between type combinations and single maltreatment types may have the greatest predictive validity. Over and above knowing about co-occurrence of maltreatment sub-types, it is important to understand what type, or constellation of types, of maltreatment have been alleged in a child's history.

Child↗
PubMed2004

Transfer of adaptation from visually guided saccades to averaging saccades elicited by double visual targets.

The adaptive mechanisms that control the amplitude of visually guided saccades (VGS) are only partially elucidated. In this study, we investigated, in six human subjects, the transfer of VGS adaptation to averaging saccades elicited by the simultaneous presentation of two visual targets. The generation of averaging saccades requires the transformation of two representations encoding the desired eye displacement toward each of the two targets into a single representation encoding the averaging saccade (averaging programming site). We aimed to evaluate whether VGS adaptation acts upstream (hypothesis 1) or at/below (hypothesis 2) the level of averaging saccades programming. Using the double-step target paradigm, we simultaneously induced a backward adaptation of 17.5 degrees horizontal VGS and a forward adaptation of 17.5 degrees oblique VGS performed along the +/- 40 degrees directions relative to the azimuth. We measured the effects of this dual adaptation protocol on averaging saccades triggered by two simultaneous targets located at 17.5 degrees along the +/- 40 degrees directions. To increase the yield of averaging saccades, we instructed the subjects to move their eyes as fast as possible to an intermediate position between the two targets. We found that the amplitude of averaging saccades was smaller after VGS adaptation than before and differed significantly from that predicted by hypothesis 1, but not by hypothesis 2, with an adaptation transfer of 50%. These findings indicate that VGS adaptation largely occurs at/below the averaging saccade programming site. Based on current knowledge of the neural substrate of averaging saccades, we suggest that VGS adaptation mainly acts at the level of the superior colliculus or downstream.

Adaptation, Physiological↗
PubMed2002

Quantitative research on the primary process: method and findings.

Freud always defined the primary process metapsychologically, but he described the ways it shows up in dreams, parapraxes, jokes, and symptoms with enough observational detail to make it possible to create an objective, reliable scoring system to measure its manifestations in Rorschach responses, dreams, TAT stories, free associations, and other verbal texts. That system can identify signs of the thinker's efforts, adaptive or maladaptive, to control or defend against the emergence of primary process. A prerequisite and a consequence of the research that used this system was clarification and elaboration of the psychoanalytic theory of thinking. Results of empirical tests of several propositions derived from psychoanalytic theory are summarized. Predictions concerning the method's most useful index, of adaptive vs. maladaptive regression, have been repeatedly verified: People who score high on this index (who are able to produce well-controlled "primary products" in their Rorschach responses), as compared to those who score at the maladaptive pole (producing primary-process-filled responses with poor reality testing, anxiety, and pathological defensive efforts), are better able to tolerate sensory deprivation, are more able to enter special states of consciousness comfortably (drug-induced, hypnotic, etc.), and have higher achievements in artistic creativity, while schizophrenics tend to score at the extreme of maladaptive regression. Capacity for adaptive regression also predicts success in psychotherapy, and rises with the degree of improvement after both psychotherapy and drug treatment. Some predictive failures have been theoretically interesting: Kris's hypothesis about creativity and the controlled use of primary process holds for males but usually not for females. This body of work is presented as a refutation of charges, brought by such critics as Crews, that psychoanalysis cannot become a science.

Defense Mechanisms↗
PubMed2006

Actions and consequences in bimanual interaction are represented in different coordinate systems.

Moving one part of the body can generate interaction forces that tend to destabilize other parts of the body. However, stability is maintained by mechanisms that predict and actively oppose these interaction forces. When our body or environment changes, these anticipatory mechanisms adapt so as to continue to produce accurate predictions. In this study, we examine the acquisition of a novel predictive coordination between the arms, in a situation in which a force is produced on one hand as a consequence of the action of the other hand. Specifically, a force was applied to the left hand that depended on the velocity of the right hand. With practice, subjects learned to stabilize the perturbed left arm during right-arm movements by predicting and actively opposing the externally applied forces. After adaptation, we examined how learning generalized to a new joint configuration of the right or left arm to investigate the coordinate systems in which the internal transformation from movement to force is represented. This revealed a dissociation between the representation of the action of the right arm and the representation of its consequence, that is the force on the left arm. The movement is represented in extrinsic coordinates related to the velocity of the hand, whereas the force resulting from the movement is represented in a joint-based intrinsic coordinate system.

Adaptation, Physiological↗
PubMed2002

Cross-cultural evidence of cognitive adaptations for social exchange among the Shiwiar of Ecuadorian Amazonia.

On the basis of evolutionary game theory, it was hypothesized that humans have an evolved cognitive specialization for reasoning about social exchange, including a subroutine for detecting cheaters. This hypothesis led to a specific prediction: Although humans are known to be poor at detecting potential violations of conditional rules in general, they should nevertheless detect them easily when the rule involves social exchange and looking for violations corresponds to looking for cheaters. This prediction was subsequently confirmed by numerous tests. Evolutionary analyses further predict that: (i) in humans, complex adaptations will be distributed in a species-typical fashion; and (ii) aspects of cognitive organization relevant to performing the evolved function of an adaptation should be more buffered against environmental and cultural variation than function-irrelevant aspects. Here we report experiments testing whether social exchange reasoning exhibits these properties of adaptations. Existing tests of conditional reasoning were adapted for nonliterate experimental subjects and were administered to Shiwiar hunter-horticulturalists of the Ecuadorian Amazon. As predicted, Shiwiar subjects were as highly proficient at cheater detection as subjects from developed nations. Indeed, the frequency of cheater-relevant choices among Shiwiar hunter-horticulturalists was indistinguishable from that of Harvard undergraduates. Also as predicted, cultural variation was confined to those aspects of reasoning that are irrelevant to social exchange algorithms functioning as an evolutionarily stable strategy. Finally, Shiwiar subjects displayed the same low performance on descriptive conditionals as subjects from developed nations. Taken together, these findings support the hypotheses that social exchange algorithms are species-typical and that their evolutionarily stable strategy (ESS)-relevant subroutines are developmentally buffered against cultural variation.

Adaptation, Psychological↗
PubMed1991

Effects of parent training on families of children with mental retardation: increased burden or generalized benefit?

Parents of children with mental retardation have become increasingly involved in special education, including training programs to facilitate teaching at home. Although some writers have argued that families accrue generalized psychological benefits of such participation, others have cautioned that the result may be increasing the burden of child-rearing. Forty-nine families of children with mental retardation were assessed before and after a parent training program, on a variety of parent, marital, and family measures. Parents reported high satisfaction with the program and showed small but statistically significant decreases in reports of symptoms of depression, parent and family problems, overall family stress, and dissatisfaction with the family's adaptability. Family characteristics were also predictive of teaching at home one year following training. The families that reported doing the least productive teaching had entered training reporting greater child-related stress and lower satisfaction with the marriage and the family.

Adaptation, Psychological↗
PubMed2000

Flexibility of saccade adaptation in the monkey: different gain states for saccades in the same direction.

Saccadic accuracy, measured as the ratio of the size of a saccade to the size of the target step that elicits it, i.e., saccade gain, can be altered by jumping the target surreptitiously during the targeting saccade. The gain change produced by this paradigm does not generalize or transfer to saccades of all sizes. Instead, the amount of transfer decreases the more the tested saccade differs in amplitude and direction from that adapted. Here, we tested the limits of this saccade-size specificity by attempting to impose quite different gain states on saccades in the same direction. We altered the saccadic gain by intrasaccadic target jumps of 30% of the initial target step, either forward to produce a gain increase or backward to produce a gain decrease. Three different conditions were studied: (1) saccades to target steps of 20 degrees or 7 degrees were adapted in individual sessions with backward and forward jumps, respectively; (2) saccades to target steps of 20 degrees caused backward target jumps during the same session in which saccades to 7 degrees target steps caused forward steps; (3) the target jumps accompanying 20 and 7 degrees saccades were the same as in (2), but in addition, there were intermediate-sized saccades to 13.5 degrees target steps with no intrasaccadic target jumps. Saccadic gain adaptation was quite flexible. In condition 2, we could simultaneously increase the gain of saccades to 7 degrees target steps while decreasing the gain of saccades to 20 degrees steps in the same direction. Intermediate horizontal saccades to 13.5 degrees target steps experienced gain reductions (average: 6.9%), which were not the sum of gain changes expected from separate 20 degrees gain decreases and 7 degrees gain increases alone, as predicted from condition 1. If adaptation at 20 degrees and 7 degrees occurred while an animal also tracked a non-adapting 13.5 degrees target step (paradigm 3), the gain reduction of saccades to the 13.5 degrees step was reduced considerably (3.4%). Thus, the mechanism that adapts saccade size can support a robust gain increase for saccades of one size while simultaneously supporting a robust gain decrease for saccades only 13 degrees larger. Furthermore, the presence during adaptation of a non-adapted target step with a size intermediate to the two adapting steps reestablishes a nearly normal gain within only 6.5 degrees of a robust gain increase and decrease. These data indicate that saccadic gain adaptation can set very different gain states for saccades with rather similar vectors.

Adaptation, Ocular↗
PubMed2002

Life history and life cycles: production and behavior of trematode cercariae in relation to host exploitation and next-host characteristics.

Life history trade-offs affect trematode parasites reproducing inside their 1st intermediate hosts. Within the constraint of the effect on host survival, parasite production of cercariae is subject to a size-numbers trade-off. Within each cercaria, resources must be partitioned between host-seeking and subsequent developmental functions. Three species of microphallid trematodes with the same 1st intermediate host (the gastropod Littorina saxatilis) were investigated. Maritrema arenaria periodically released many small cercariae. Microphallus similis released fewer, 15% larger, cercariae without periodicity. Microphallus similis cercariae were strong swimmers, moving toward the dark and downward in turbulent water, whereas Ma. arenaria cercariae remained suspended. Maritrema arenaria cercariae, although smaller in body and tail size, were produced at an average daily volume nearly twice that of M. similis. These differences are interpreted as transmission adaptations related to mobility and predictability of the 2nd intermediate host. Microphallus similis, with a mobile and less predictable crab host, adopted a 'bethedging' prolonged production of fewer cercariae by less intensive host exploitation, each cercaria having a high allocation to host-seeking behavior. Maritrema arenaria, with predictable sessile barnacle hosts, produced less mobile but potentially longer-lived cercariae in larger numbers. Microphallus piriformes metacercariae remain in the gastropod host. The number of M. piriformes metacercariae increased in larger hosts. The 3 species differed in the number of sporocysts and (meta)cercariae per sporocyst within the gastropod but not in the within-host volume of parasites. Variation in host exploitation and life history appeared adaptive for transmission to the next host.

Animals↗
PubMed1996

The inheritance of phenotypes: an adaptation to fluctuating environments.

We discuss simple models for the evolution of rates of spontaneous and induced heritable phenotypic variations in a periodically fluctuating environment with a cycle length between two and 100 generations. For the simplest case, the optimal spontaneous transition rate between two states is approximately 1/n (where n is the cycle length). It is also shown that selection for the optimal transition rate under these conditions is surprisingly strong. When n is small, this means that the heritable variations are produced by non-classical inheritance systems, including non-DNA inheritance systems. Thus, it is predicted that in genes controlling adaptation to such environments, non-classical genetic effects are likely to be observed. We argue that the evolution of spontaneous and induced heritable transitions played an important role in the evolution of ontogenies of both unicellular and multicellular organisms. The existence of a machinery for producing induced heritable phenotypic variations introduces a "Lamarckian" factor into evolution.

Adaptation, Physiological↗
PubMed1975

Effect of training on cardiovascular response to exercise in women.

Seventeen women (mean age 31 yr) participated in a training program divided into an initial 9-wk period and a subsequent 52-wk period, during which time 6 continued to exercise and the remainder detrained. Improvements in VO2max were significant (+34%) during the initial 9 wk and small (+5%) for the final 52 wk. Four women who stopped training showed a decrease in VO2max (-10%) during the last phase. During the initial 9 wk, central adaptation was important, with SV showing an increase of 28% at 80% VO2max. Peripheral adaptation (a-v O2 difference) was unchanged. Subjects who trained an additional 52 wk showed a slight drop in SV at submaximal work loads from the initial increase following the first 9 wk. When compared with the initial test the change at 9 wk in peripheral adaptation was a small and nonsignificant rise, followed by a significant increase at 61 wk. Women who are very unfit initially (predicted VO2max of 28 ml/kg-min), apparently adapt to the initial training with a central change followed by a much stronger peripheral adaptation during a longer training program.

Cardiac Output↗
PubMed2001

Adaptation as a mediator of intimate abuse and traumatic stress in battered women.

The purpose of this research was to test one aspect of a proposed middle-range theory synthesized from the Roy adaptation model and linked with the framework of post-traumatic stress. A predictive-correlational design was used to examine adaptation as a mediator of traumatic stress in battered women. Analysis included regression and path analytic procedures. Results indicated (a) direct relationships between the focal stimuli of abuse and the response of post-traumatic stress disorder and (b) adaptation in the physiologic, self-concept, and interdependence modes partially mediated the relationship between the focal stimuli of abuse and the response of post-traumatic stress disorder in battered women.

Adaptation, Psychological↗
PubMed1988

Adaptive staircase techniques in psychoacoustics: a comparison of human data and a mathematical model.

Data from a simple tone-in-noise simultaneous masking task were used to evaluate each of two common adaptive staircase rules (a "1 up 2 down" rule and a "1 up 3 down" rule) and the parameter estimation by sequential testing (PEST) technique in combination with each of two psychophysical procedures [a two-alternative forced-choice (2AFC) and a three-alternative forced-choice (3AFC) procedure]. These human data were compared to predictions generated by a mathematical model based on Markov theory. The model predicts that threshold estimates obtained with the adaptive techniques should be equal to those derived with equivalent "fixed signal level" techniques. However, the human data indicate that the adaptive techniques tend to yield lower thresholds. The model predicts that the standard error of a threshold estimate obtained from an adaptive technique will decrease and approach zero as the number of trials used to compute the estimate increases. The human data show greater variability than predicted and approach a nonzero value as the number of trials increases. The predictions of the model suggest that the commonly used combination of the 2AFC procedure and the 1 up 2 down rule is the least efficient method of estimating a threshold and that the 3AFC procedure in combination with the 1 up 3 down rule is the most efficient method. The human data are less consistent, but generally show the combination of the 2AFC procedure and the 1 up 2 down rule to be one of the least efficient methods. Possible explanations for the differences between the model's predictions and the human data, as well as suggestions for laboratory practice, are discussed.

Adult↗
PubMed2006

Adaptation to visual feedback delays in manual tracking: evidence against the Smith Predictor model of human visually guided action.

We report adaptation to delayed visual feedback during a manual tracking task, testing the nature of the adapted responses with frequency analysis. Two groups of seven subjects tracked unpredictable targets using a handheld joystick, alternating between pursuit and compensatory display trials. The test group then practised for 1 h per day with a visual feedback delay of 300 ms; the control group practice under normal undelayed conditions. Introduction of the visual feedback delay significantly disrupted tracking performance, with an increase in errors and a reduction in frequency of corrective movements. Subjects showed clear evidence of adaptation during the 5 day experiment, decreasing tracking error and decreasing the mean power of intermittent corrections. However, there was no evidence of a return towards the initial high frequency intermittent tracking. We suggest that the adaptation observed in this study reflects the modification of predictive feedforward actions, but that these data do not support control based on Smith Prediction.

Adaptation, Physiological↗
PubMed2000

Learning of action through adaptive combination of motor primitives.

Understanding how the brain constructs movements remains a fundamental challenge in neuroscience. The brain may control complex movements through flexible combination of motor primitives, where each primitive is an element of computation in the sensorimotor map that transforms desired limb trajectories into motor commands. Theoretical studies have shown that a system's ability to learn action depends on the shape of its primitives. Using a time-series analysis of error patterns, here we show that humans learn the dynamics of reaching movements through a flexible combination of primitives that have gaussian-like tuning functions encoding hand velocity. The wide tuning of the inferred primitives predicts limitations on the brain's ability to represent viscous dynamics. We find close agreement between the predicted limitations and the subjects' adaptation to new force fields. The mathematical properties of the derived primitives resemble the tuning curves of Purkinje cells in the cerebellum. The activity of these cells may encode primitives that underlie the learning of dynamics.

Brain↗