Carrying children, groceries, and water across varying terrain: Changes in gait and comfortable walking speed.

BACKGROUND: Carrying items of substantial weight and value in one's arms while traversing challenging terrain is a common task that requires considerable care. Carrying valuable (e.g., child) or variable (e.g., water) items, compared to stable ones (e.g., groceries) demands increased coordination, and is likely to lead to slower comfortable walking speed (CWS) and altered gait mechanics, especially on difficult terrain. RESEARCH QUESTION: How are gait parameters altered by carrying items of substantial weight and varying value and dynamics across more and less demanding terrain? METHODS: In two experiments, participants carried their child, an equally weighted sack of groceries, or an open bucket of water in the same manner across level floor and across uneven stairs of varying heights with gaps between them. Kinematics were assessed for both terrains; kinetics were measured for one step up and one step down on stairs. RESULTS: Mixed models ANOVAs with repeated measures revealed that CWS on uneven stairs was approximately 65 % of CWS for level floor, regardless of the item carried. Step-to-step coefficients of variation for step length and CWS were also greater. Water was carried most slowly, with shorter steps on level floor and reduced accelerations on uneven stairs. CWS with children and groceries did not differ. SIGNIFICANCE: Carrying items of weight and worth with varying dynamics across more and less challenging terrain illustrates the ecological complexity of walking. Terrain requiring greater flexibility, strength, and coordination reduced CWS substantially, a complexity-speed tradeoff. More variable, difficult to control items altered CWS and other gait patterns regardless of terrain difficulty, suggesting terrain and item dynamics contributed independently to gait adjustments. More valuable items were not carried more slowly than less valuable ones. Carrying tasks deserve greater attention in research and clinical assessment.

Lifting, tasting, and carrying: The interaction of magnitude and valence effects in time perception.

Magnitude effects (e.g., heavier or faster is longer) and valence effects (e.g., negative > positive) are widely observed in time perception studies, but not well understood. In four experiments, we explored how different action contexts (e.g., tasting, lifting) affected magnitude and valence effects. In two experiments a valence effect occurred: Tasting a sweet food (watermelon) led to temporal underestimations relative to a neutral stimulus, while sour and bitter foods led to overestimations. However, when the same foods were presented in a lifting context a magnitude effect occurred: Reproduced times for the heavier food (watermelon) were overestimated relative to the lighter foods. In a fourth experiment magnitude and valence interacted: Imagining tasting increasing amounts of lemon or carrying increasing loads of lemon, both negative, yielded magnitude effects; however, imagining carrying lemons to feed malnourished people, which was positive, did not. Results present challenges for several common theoretical approaches (e.g., arousal, attention, common magnitude theory) but provide support for affordance theory and perceptual salience theory. Timing depends on action relevance and is jointly shaped by valence and magnitude.

We agree and we disagree, which is exactly what most people do most of the time.

Humans are continually diverging and converging with respect to each other. Research across many domains suggests that differentiation and integration are aspects of a more complex set of dynamics, and are not step-wise but interdependent and continuous. Research on conformity in particular reveals that divergence and dissent are forms of cooperation, reflecting concerns for both individual and group integrity.

Rethinking conformity and imitation: divergence, convergence, and social understanding.

Social and developmental psychologists have stressed the pervasiveness and strength of humans' tendencies to conform and to imitate, and social anthropologists have argued that these tendencies are crucial to the formation of cultures. Research from four domains is reviewed and elaborated to show that divergence is also pervasive and potent, and it is interwoven with convergence in a complex set of dynamics that is often unnoticed or minimized. First, classic research in social conformity is reinterpreted in terms of truth, trust, and social solidarity, revealing that dissent is its most salient feature. Second, recent studies of children's use of testimony to guide action reveal a surprisingly sophisticated balance of trust and prudence, and a concern for truth and charity. Third, new experiments indicate that people diverge from others even under conditions where conformity seems assured. Fourth, current studies of imitation provide strong evidence that children are both selective and faithful in who, what, and why they follow others. All of the evidence reviewed points toward children and adults as being engaged, embodied partners with others, motivated to learn and understand the world, others, and themselves in ways that go beyond goals and rules, prediction and control. Even young children act as if they are in a dialogical relationship with others and the world, rather than acting as if they are solo explorers or blind followers. Overall, the evidence supports the hypothesis that social understanding cannot be reduced to convergence or divergence, but includes ongoing activities that seek greater comprehensiveness and complexity in the ability to act and interact effectively, appropriately, and with integrity.

Speaking from ignorance: not agreeing with others we believe are correct.

Values-pragmatics theory (Hodges & Geyer, 2006) predicts that people will sometimes disagree with others they believe are correct, for reasons similar to those explaining agreement with incorrect answers in an Asch (1956) situation. In 3 experiments, we found evidence that people in a position of ignorance sometimes do not agree with the correct answers of others in positions of knowledge. Experiments 1a and 1b found this speaking-from-ignorance (SFI) effect occurred 27% of the time. Experiment 2 introduced experimental controls and self-report data indicating that the SFI effect (30%) was generated by realizing values (e.g., truth, social solidarity) and pragmatic constraints to act cooperatively, rather than by a wide array of alternatives (e.g., normative pressure, reactance). Experiment 3 experimentally manipulated concern for truthfulness, yielding 49% nonagreeing answers, even though there were monetary incentives to give correct, agreeing answers. The overall pattern suggests that people are not so much conformists or independents as they are cooperative truth tellers under social and moral constraints. Results, while surprising for social influence theories, illustrate the dynamics of divergence and convergence that appear across studies in cultural anthropology and developmental psychology, as well as in social psychology.

Looking up to others: Social status, Chinese honorifics, and spatial attention.

Two experiments were carried out to investigate whether social status encoded in Chinese honorifics has metaphorical effects on up-down spatial orientation. In Experiment 1, participants judged whether a word was an elevating or denigrating term immediately prior to judging whether an arrow was pointing up or down. Arrow orientation was identified faster when its direction was congruent with the perceived social status of the preceding honorific (e.g., elevating word and up arrow). In Experiment 2, participants identified the letter p or q after judging whether honorifics were elevating or denigrating terms. Letters were identified faster when placed at the top of the screen following elevating terms, and faster at the bottom following denigrating terms. These results suggest that the mere activation of social status differences by honorific terms orients attention toward schema-congruent space. Social status appears to have pragmatic effects, not only for lexical decision-making, but also in where Chinese speakers are most likely to look.

The weight of time: affordances for an integrated magnitude system.

In five experiments we explored the effects of weight on time in different action contexts to test the hypothesis that an integrated magnitude system is tuned to affordances. Larger magnitudes generally seem longer; however, Lu and colleagues (2009) found that if numbers were presented as weights in a range heavy enough to affect lifting, the "larger seems longer" effect was enhanced, but it was eliminated with weights too light to affect lifting. Experiments 1 and 2 revealed that actually lifting kilogram and gram weights had effects parallel to symbolized weights, suggesting that Lu et al.'s task implicitly evoked a lifting context. Experiments 3 and 4 showed that weights too heavy (e.g., tons) or too light to be discriminated by lifting, but relevant to other affordances (e.g., grams of a toxin) had effects on time as large or larger than for kilograms. Experiment 5 showed that the effect for grams in a toxicology context did not generalize to the lifting task of Experiment 2. Weight appears to integrate with other magnitudes when it is relevant to meaningful actions, including but not limited to lifting.

New Affordances for Language: Distributed, Dynamical, and Dialogical Resources.

In introducing the articles of this special issue on language, which grew out of the conference "Grounding Language in Perception and (Inter) Action," we take the opportunity to reflect on fundamental aspects of speaking and listening to others that are often overlooked. The act of conversing is marked by context sensitivity, interdependency, impredicativity, irreversibility, and responsibility, among other things. Language entails real work: it involves real movements in physical, social, and moral orders that are distributed across a wide array of spatial-temporal scales (e.g., evolutionary, historical); yet there is a dimension of play "at work" as well. These workings of language are embedded and embodied in distributed ways that reveal the fundamentally social, public nature of the activity. It is a form of coaction that is dialogical and dynamic in ways that may point to deeper understandings of what it means for perception to be direct and for action to be specific. Language locates us.

Contextual effects on number-time interaction.

Time perception has long been known to be affected by numerical representations. Recent studies further demonstrate that when participants estimate the duration of Arabic numbers, number magnitude, though task-irrelevant, biases duration judgment to produce underestimation for smaller numbers and overestimation for larger numbers. Such effects were found in the present study to be significantly reduced when a weight unit gram was suffixed to the numbers rendering the mental magnitude differences between different numbers less distinctive. The effects were enhanced when a different unit kilogram was suffixed to the numbers enlarging the perceived magnitude differences between different numbers. The results indicate that effects of number magnitude on duration estimation should not be attributed to the mathematical differences between numbers but to how the numbers are perceived to differ from each other in magnitude in specific contexts when they denote concrete items. The results also provide new evidence for the theoretical proposal of a common generalized magnitude system and indicate that the system must be extended to include other action-oriented magnitudes, such as weight.

A nonconformist account of the Asch experiments: values, pragmatics, and moral dilemmas.

This article offers a new approach to Asch's (1956) influential studies relating physical and social perception. Drawing on research on values, conversational pragmatics, cross-cultural comparisons, and negotiation, the authors challenge the normative assumptions that have led psychologists to interpret the studies in terms of conformity. A values-pragmatics account is offered that suggests that participants attempt to realize multiple values (e.g., truth, social solidarity) in an inherently frustrating situation by tacitly varying patterns of dissent and agreement to communicate larger scale truths and cooperative intentions. Alternative theories (e.g., embarrassment, attribution) are compared and empirical implications of the values-pragmatics account are evaluated. The possibility of multiple strategies promoting group survival and the proper role of moral evaluation in social psychological research are considered.