The goal of locomotion: Separating the fundamental task from the mechanisms that accomplish it

Human locomotion has been well described but is still not well understood. This is largely true because the observable aspects of locomotion—neuromuscular activity that generates forces and motions—relate to both the task solution and the problem being solved. Identifying the fundamental task achieved in locomotion makes it possible to critically evaluate the motor control strategy used to accomplish the task goal. We contend that the readily observed movements and activities of locomotion should be considered mechanism(s). Our proposal is that the fundamental task of walking and running is analogous to flight, and should be defined in terms of the interaction of the individual’s mass with the medium in which it moves: a low-density fluid for flight, or the supporting substrate for legged locomotion. A rigorous definition of the fundamental task can help identify the constraints and opportunities that influence its solution and guide the selection of appropriate mechanisms to accomplish the task effectively. The results from robotics-based modeling studies have demonstrated how the interaction of the mass and substrate can be optimized, making the goal of movement a defined trajectory of the individual’s mass. We assessed these concepts by evaluating the ground reaction forces generated by an optimization model that satisfies the task but uses none of the mechanisms that are available to the human leg. Then we compared this model to normal human walking. Although it is obvious that the specific task of locomotion changes with a variety of movement challenges, clearly identifying the fundamental task of locomotion puts all other features in an interpretable context.     

Cognitive consistency and the formation of interpersonal attitudes: Cognitive balance affects the encoding of social information

Three studies investigated the role of cognitive balance in the formation of interpersonal attitudes. Experiment 1 found evidence for balanced triads when participants first formed an attitude about one person, and then learned about this person’s sentiments about another individual. Interestingly, balanced triads were obtained for both explicitly and implicitly assessed attitudes. Experiment 2 indicated that the pattern of interpersonal relations does not result in balanced triads, when participants first learn about the relationship between two neutral individuals, and then receive evaluative information about one of the two individuals. In this case, observed sentiments and evaluative information affected attitudes in an additive rather than interactive manner. Experiment 3 replicated these findings by manipulating valence, observed sentiments, and order of information acquisition in a single study. Taken together, these results suggest that cognitive balance influences the encoding of social information, rather than the retroactive construal of evaluative judgments.     

What Makes Mental Associations Personal or Extra‐Personal? Conceptual Issues in the Methodological Debate about Implicit Attitude Measures

Over the last decade, a new class of indirect measurement procedures has become increasingly popular in many areas of psychology. However, these implicit measures have also sparked controversies about the nature of the constructs they assess. One controversy has been stimulated by the question of whether some implicit measures (or implicit measures in general) assess extra‐personal rather than personal associations. We argue that, despite empirical and methodological advances stimulated by this debate, researchers have not sufficiently addressed the conceptual question of how to define extra‐personal in contrast to personal associations. Based on a review of possible definitions, we argue that some definitions render the controversy obsolete, whereas others imply fundamentally different empirical and methodological questions. As an alternative to defining personal and extra‐personal associations in an objective sense, we suggest an empirical approach that investigates the meta‐cognitive inferences that make a given association subjectively personal or extra‐personal for the individual.     

How people explain actions performed by groups and individuals.

The authors explore whether people explain intentional actions performed by groups differently from actions performed by individuals, A theoretical framework is offered that distinguishes between 2 modes of explanation: the agent's reasons (beliefs or desires in light of which the agent decided to act) and causal histories of reasons (CHRs; factors that preceded and brought about the agent's reasons). The authors develop the hypothesis that people use more CHR explanations when explaining group actions than when explaining individual actions. Study 1 demonstrates this asymmetry. Studies 2 and 3 explore 2 necessary conditions for the asymmetry: that the group be perceived as an aggregate of individual actors rather thin as a jointly acting group and that explainers have general information available about the group. Discussion focuses on people's perception of groups as entities and agents.     

When the method makes a difference: Antagonistic effects on “automatic evaluations” as a function of task characteristics of the measure

Researchers often employ implicit measures as dependent variables to investigate processes of attitude formation and change. In such studies, experimentally induced differences are typically interpreted as reflecting change in automatic evaluations. We argue that experimentally induced effects on implicit measures may not always reflect genuine changes in evaluative responses, but can be driven by the mechanisms underlying the measurement procedure. In line with this assumption, the present research shows that these mechanisms can produce opposite effects of the same experimental manipulation for otherwise equivalent implicit measures. These results indicate that merely observing experimental effects on implicit measures does not allow direct inferences regarding changes in automatic evaluations. Instead, psychological interpretations of such effects hinge upon the mechanics of how a given measurement procedure responds to variations in the context. Implications for research using implicit measures are discussed.     

Psychopathology of parenthood: Implications for mental health of children

Psychiatric illness among mothers of infants and young children is believed to have serious implications for the child's cognitive and socio-emotional development, and presents a continuing crisis in the provision of reliable parental care: frequent rehospitalizations are disruptive both for the parent-child tie, and for the stability of the family unit. This chapter reviews findings regarding the impact of maternal psychiatric disorders upon the child's development, and intervention programs designed to reduce the impact of these disorders upon both child and family. In addition to considering families in which there is major psychopathology, problems are noted among families in which “an ordinary devoted mother” shows markedly lowered morale, but does not become a part of the mental health system. Findings from a number of innovative intervention programs are summarized in terms of possible next steps in working with these troubled parents and their children.     

Separating multiple processes in implicit social cognition: the quad model of implicit task performance

The authors argue that implicit measures of social cognition do not reflect only automatic processes but rather the joint contributions of multiple, qualitatively different processes. The quadruple process model proposed and tested in the present article quantitatively disentangles the influences of 4 distinct processes on implicit task performance: the likelihood that automatic bias is activated by a stimulus; that a correct response can be determined; that automatic bias is overcome; and that, in the absence of other information, a guessing bias drives responses. The stochastic and construct validity of the model is confirmed in 5 studies. The model is shown to provide a more nuanced and detailed understanding of the interplay of multiple processes in implicit task performance, including implicit measures of attitudes, prejudice, and stereotyping.     

Ambiguous pronoun resolution: contrasting the first-mention and subject-preference accounts

A visual-world eye-tracking experiment investigated the influence of order of mention and grammatical role on resolution of ambiguous pronouns in Finnish. According to the first-mention account, general cognitive structure-building processes make the first-mentioned noun phrase the preferred antecedent of an ambiguous pronoun. According to the subject-preference account, the preferred antecedent is the grammatical subject of the preceding clause or sentence. Participants listened to sentences in either subject-verb-object or object-verb-subject order; each was followed by a sentence containing an ambiguous pronoun that referred to either the subject or the object. Participants' eye movements were monitored while they looked at pictures representing the two possible antecedents of each pronoun. Analyses of the fixations on the pictures showed that listeners used both order-of-mention and grammatical-role information to resolve ambiguous pronouns.     

A role for Synapsin in associative learning: the Drosophila larva as a study case

Synapsins are evolutionarily conserved, highly abundant vesicular phosphoproteins in presynaptic terminals. They are thought to regulate the recruitment of synaptic vesicles from the reserve pool to the readily-releasable pool, in particular when vesicle release is to be maintained at high spiking rates. As regulation of transmitter release is a prerequisite for synaptic plasticity, we use the fruit fly Drosophila to ask whether Synapsin has a role in behavioral plasticity as well; in fruit flies, Synapsin is encoded by a single gene (syn). We tackled this question for associative olfactory learning in larval Drosophila by using the deletion mutant syn^97CS, which had been backcrossed to the Canton-S wild-type strain (CS) for 13 generations. We provide a molecular account of the genomic status of syn^97CS by PCR and show the absence of gene product on Western blots and nerve-muscle preparations. We found that olfactory associative learning in syn^97CS larvae is reduced to ~50% of wild-type CS levels; however, responsiveness to the to-be-associated stimuli and motor performance in untrained animals are normal. In addition, we introduce two novel behavioral control procedures to test stimulus responsiveness and motor performance after “sham training.” Wild-type CS and syn^97CS perform indistinguishably also in these tests. Thus, larval Drosophila can be used as a case study for a role of Synapsin in associative learning.     

Olfactory blocking and odorant similarity in the honeybee

Blocking occurs when previous training with a stimulus A reduces (blocks) subsequent learning about a stimulus B, when A and B are trained in compound. The question of whether blocking exists in olfactory conditioning of proboscis extension reflex (PER) in honeybees is under debate. The last published accounts on blocking in honeybees state that blocking occurs when odors A and B are similar (the "similarity hypothesis"). We have tested this hypothesis using four odors (1-octanol, 1-nonanol, eugenol, and limonene) chosen on the basis of their chemical and physiological similarity (experiment 1). We established a generalization matrix that measured perceptual similarity. Bees in the "block group" were first trained with an odor A and, in the second phase, with the mixture AB. Bees in the "novel group" (control group) were first trained with an odor N and, in the second phase, with the mixture AB. After conditioning, bees in both groups were tested for their response to B. We assayed all 24 possible combinations for the four odors standing for A, B, and N. We found blocking in four cases, augmentation in two cases, and no difference in 18 cases; odor similarity could not account for these results. We also repeated the experiments with those six odor combinations that gave rise to the similarity hypothesis (experiment 2: 1-hexanol, 1-octanol, geraniol) and found augmentation in one and no effect in five cases. Thus, blocking is not a consistent phenomenon, nor does it depend on odor similarity.