Developmental stability in jumping.

The principles of dynamical systems were used to study the effects of changing internal (i.e., developing subsystems) and external (i.e., task demands) constraints on the development of jumping. Children, 3, 5, 7, and 9 years old, and 3 groups of adults—of average skill, skilled in volleyball, and skilled in gymnastics—were filmed performing two different tasks, a standing long jump and a vertical jump. The results revealed that despite changes in both external and internal constraints, there were no differences in the pattern of coordination for jumping. Differences were found in the position and magnitude variables. Clearly, the constraints manipulated here were insufficient to disrupt the stability of the jump's coordination. We suggest that these results indicate that jumping is a stable movement organization that transcends the changes in constraints associated with developing subsystems and particular task demands. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

S-R compatibility between response position and destination of apparent motion: Evidence of the detection of affordances.

In choice reaction time, stimuli and responses in some combinations (e.g., based on spatial arrangement) are faster than in other combinations. To test whether motion toward a position yields faster responses at that position, a computer-generated square in front of one hand appeared to move either toward that hand or toward the other hand. Compatible responses (e.g., motion toward left hand/left response) were faster than incompatible responses, even when that opposed traditional positional compatibility. In Experiment 2, subjects responded to the same stimuli but with both hands left, right, or on the body midline. Medial responses were the fastest, showing that destination, rather than mere relative position, was a critical variable. It was suggested that spatial compatibility effects are not unique to position but apply to a variety of task situations, describable by J. J. Gibson's theory of affordances, in which he claims that one perceives the actions (e.g., catching) permitted in a situation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evolution of behavioral attractors with learning: Nonequilibrium phase transitions.

Learning a bimanual coordination task (synchronization to a visually specified phasing relation) was studied as a dynamical process over 5 days of practicing a required phasing pattern. Systematic probes of the attractor layout of the 5 Ss' coordination dynamics (expressed through a collective variable, relative phase) were conducted before, during, and after practice. Depending on the relationship between the initial coordination dynamics (so-called intrinsic dynamics) and the pattern to be learned (termed behavioral information, which acts as an attractor of the coordination dynamics toward the required phasing), qualitative changes in the phase diagram occurred with learning, accompanied by quantitative evidence for loss of stability (phase transitions). Such effects persisted beyond 1 wk. The nature of change due to learning (e.g., abrupt vs gradual) is shown to arise from the cooperative or competitive interplay between behavioral information and the intrinsic dynamics. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Challenging the notion of a thematic preference in young children.

Many researchers have argued that early cognitive development is characterized by a conceptual preference for thematic over taxonomic relations. However, more recent research indicates that infants and toddlers may not favor thematic relations. To resolve this discrepancy, the conceptual preferences of children ranging from 2 to 4 years of age were examined, using a forced-choice task including a target (e.g., a carrot), a thematic alternative (e.g., a rabbit), and a taxonomic alternative (e.g., a tomato). The effects of age, experimenter's instructions, hierarchical level (basic vs. superordinate), and stimulus medium (pictures vs. objects) were examined systematically. Children revealed no pervasive preference for either thematic or taxonomic relations. This challenges the notion of a developmental shift in conceptual preferences and suggests a more continuous trajectory in early conceptual development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Creativity as flexible cognitive control.

Creative individuals have been described in terms suggestive of greater automatic processing (e.g., defocused attention, looser associations) and greater controlled processing (e.g., greater abilities to focus while working on a creative task). Both views cannot be correct from a static ability-related perspective. On the other hand, both views could be correct if creative individuals are better able to modulate the functioning of their cognitive control system in a context-sensitive manner. The present study (N = 50) assessed individual differences in creativity in terms of original responses on the Torrance Test of Creative Thinking (Torrance, 1974) and also in terms of creative behavior on the Creative Achievement Questionnaire (Carson, Peterson, & Higgins, 2005). The same participants performed a color–word Stroop task. Creative individuals were neither more nor less capable of overriding cognitive conflicts on incongruent (relative to congruent) Stroop trials. On the other hand, creative individuals displayed more flexible cognitive control, as defined by greater cognitive control modulation from trial to trial. Implications for theories of creativity and its underlying processing basis are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Construing action abstractly and blurring social distinctions: Implications for perceiving homogeneity among, but also empathizing with and helping, others.

Most people's actions serve goals that, defined abstractly enough, are quite similar to one another. The authors thus proposed, and found, that construing action in abstract (vs concrete) terms relates to perceiving greater similarity among persons both within and across different social groups (Studies 1-3). By fostering perspective taking, viewing action abstractly also related to empathizing with and expressing willingness to help nonstigmatized and stigmatized others (e.g., AIDS patients; Studies 3-5) and to donating money to help those in need (Study 6). These findings held when controlling for ideological, motivational, and broad personality variables. Abstract action construals, then, appear to blur social distinctions, fostering perspective taking and empathy on the one hand but also perceptions of group homogeneity on the other. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A guide to constructs of control.

An integrative framework, designed to organize the heterogeneous constructs related to "control," is based on 2 fundamental distinctions: (a) objective, subjective, and experiences of control; and (b) agents, means, and ends of control. The framework is used to analyze more than 100 terms, such as sense of control, proxy control, and primary control. It is argued that although many terms reflect aspects of perceived control (both distinct and overlapping), some are more usefully considered aspects of objective control conditions (e.g., contingency), potential antecedents of perceived control (e.g., choice), potential consequences (e.g., secondary control), sources of motivation for control (e.g., mastery), or other sources of motivation (e.g., autonomy). Implications for theory, measurement, research, and intervention are explored. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intrinsic dynamics of social judgment.

Ss expressed their moment-to-moment feelings about a target on a computer screen. In the 1st study, the target was a positive, negative, or mixed-valence acquaintance; in the 2nd study, the target was a liked vs disliked acquaintance who committed a positive vs negative act. Several dynamic measures were derived from the positioning of the cursor (sampled 10 times per sec) over a 2-min period. The dimension of the structure underlying the observed dynamics was also assessed. Both sets of measures varied meaningfully across targets (e.g., feelings changed at a relatively fast and unstable rate for mixed-valence targets) and were correlated with self-report measures (e.g., instability in rate of movement was associated with self-reported uncertainty in feelings). Discussion centers on the viability and usefulness of framing social judgment in terms of dynamical systems concepts and principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Measuring individual differences in implicit cognition: the implicit association test

An implicit association test (IAT) measures differential association of 2 target concepts with an attribute. The 2 concepts appear in a 2-choice task (2-choice task (e.g., flower vs. insect names), and the attribute in a 2nd task (e.g., pleasant vs. unpleasant words for an evaluation attribute). When instructions oblige highly associated categories (e.g., flower + pleasant) to share a response key, performance is faster than when less associated categories (e.g., insect & pleasant) share a key. This performance difference implicitly measures differential association of the 2 concepts with the attribute. In 3 experiments, the IAT was sensitive to (a) near-universal evaluative differences (e.g., flower vs. insect), (b) expected individual differences in evaluative associations (Japanese + pleasant vs. Korean + pleasant for Japanese vs. Korean subjects), and (c) consciously disavowed evaluative differences (Black + pleasant vs. White + pleasant for self-described unprejudiced White subjects).     

Pointing errors reflect biases in the perception of the initial hand position

By comparing the visuomotor performance of 10 adult, normal subjects in three tasks, we investigated whether errors in pointing movements reflect biased estimations of the hand starting position. In a manual pointing task with no visual feedback, subjects aimed at 48 targets spaced regularly around two starting positions. Nine subjects exhibited a similar pattern of systematic errors across targets, i.e., a parallel shift of the end points that accounted, on average, for 49% of the total variability. The direction of the shift depended on the starting location. Systematic errors decreased dramatically in the second condition where subjects were allowed to see their hand before movement onset. The third task was to use a joystick held by the left hand to estimate the location of their (unseen) right hand. The systematic perceptual errors in this condition were found to be highly correlated with the motor errors in the first condition. The results support the following conclusions. 1) Kinesthetic estimation of hand position may be consistently biased. Some of the mechanisms responsible for these biases are always active, irrespective of whether position is estimated overtly (e.g., with a matching paradigm), or covertly as part of the motor planning for aimed movements. 2) Pointing errors reflect to a significant extent the erroneous estimation of initial hand position. This suggests that aimed hand movements are planned vectorially, i.e., in terms of distance and direction, rather than in terms of absolute position in space.     

Attention and handedness in bimanual coordination dynamics.

Predictions concerning the effects of handedness and attention on bimanual coordination were made from a dynamical model that incorporates the body's lateral asymmetry. Both handedness and the direction of attention (to the left or right) were manipulated in an inphase 1:1 frequency locking task. Left-handed and right-handed participants had to coordinate the planar oscillations of 2 handheld pendulums while 1 pendulum oscillated between spatial targets positioned over either the left or right hand. Predictions from the model were that participants would show a phase lead with the preferred hand, and that, although the phase lead would be greater when attention was directed to the preferred hand, the variability of relative phase would be lower. Confirmation of these predictions suggests that the dynamical perspective offers the possibility of studying handedness and attention without compromising theoretical precision or experimental control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multidimensional scaling of the causes for negative interpersonal behavior.

Conducted studies to determine empirically the dimensions underlying attributions made for negative behavior in a close interpersonal relationship (a marriage). 96 university students rated the similarity of 13 causes given either by the enactor of a negative behavior (i.e., the actor) or by the person affected by the behavior (the partner or spouse). A multidimensional scaling analysis of these data yielded 2 dimensions in each condition. The interpretation of these dimensions was guided by data from 68 additional Ss who rated the 13 causes on bipolar scales (e.g., temporary–permanent). Dimension 1 in both conditions was interpreted as "positive vs negative attitude toward spouse." Dimension 2 of the actor condition was interpreted as "intentional vs unintentional" and Dimension 2 of the partner condition as "actor's traits vs circumstances or states." These dimensions are discussed in relation to the a priori causal distinctions made in current attribution writings and previous findings concerning actor–observer biases. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Processing strategies and letter spacing in the simultaneous- and successive-display matching tasks.

The study examines the effect of adding extra blank space between the letters of eight-letter pseudowords (e.g., HEMINDOL vs. H E M I N D O L) on subjects' performance in both a simultaneous- and a successive-display matching task. The experiment shows that the effects of the manipulation depend on the task. In the simultaneous-display condition extra spacing between letters served to reduce response latencies, whereas in the successive-display condition the extra space between letters increased response latencies. The results belie an explanation based on visual factors such as retinal acuity and lateral masking and are discussed in terms of an information processing account which includes a spacing-sensitive operator. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Movement sequence-related activity reflecting numerical order of components in supplementary and presupplementary motor areas

The supplementary motor area (SMA) and presupplementary motor areas (pre-SMA) have been implicated in movement sequencing, and neurons in SMA have been shown to encode what might be termed the relational order among sequence components (e.g., movement X followed by movement Y). To determine whether other aspects of movement sequencing might also be encoded by SMA or pre-SMA neurons, we analyzed task-related activity recorded from both areas in conjunction with a sequencing task that dissociated the numerical order of components (e.g., movement X as the 2nd component, irrespective of which movements precede or follow X). Sequences were constructed from eight component movements, each characterized by three spatial variables (origin, direction, and endpoint). Task-related activity recorded from 56 SMA and 63 pre-SMA neurons was categorized according to both the epoch (delay, reaction time, and movement time) and the spatial variable or component movement with which it was associated. All but one instance of task-related activity was selective for one of the spatial variables (SV-selective) rather than for any of the component movements themselves. Of 110 instances of SV-selective activity in SMA, 43 (39%) showed significant effects of numerical order. The corresponding incidence in pre-SMA, 82 (71%) of 116, was substantially higher (P < 0.00001). No effects of numerical order were evident among the hand paths, movement times, or electromyographic activity associated with task performance. We concluded that neurons in SMA and pre-SMA may encode the numerical order of components, at least for sequences that are distinguished mainly by that aspect of component ordering.     

Evidence against the computation of abstract letter identities in visual processing.

Conducted 2 studies conceptually similar to the study of D. Besner et al (see record 1985-05766-001) in which letter strings were reorganized into sets where the single letters that were different were phonologically similar (e.g., G vs C) or dissimilar (e.g., G vs K). Latencies for same–different decisions about mixed-case letter strings were faster when the different letters were phonologically dissimilar. Results suggested skilled readers access name codes of individual letters in making their speeded classifications. In the present studies with 16 undergraduates, phonological similarity was manipulated in either the 1st or 4th letter of a mixed-case 4-letter string. A similarity effect was found when the 1st letter was varied. Results are not consistent with the view that abstract letter identities are computed in the course of same–different decisions about simultaneously presented mixed-case displays. (French abstract) (12 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Three-dimensional organization of otolith-ocular reflexes in rhesus monkeys. I. Linear acceleration responses during off-vertical axis rotation

1. The dynamic properties of otolith-ocular reflexes elicited by sinusoidal linear acceleration along the three cardinal head axes were studied during off-vertical axis rotations in rhesus monkeys. As the head rotates in space at constant velocity about an off-vertical axis, otolith-ocular reflexes are elicited in response to the sinusoidally varying linear acceleration (gravity) components along the interaural, nasooccipital, or vertical head axis. Because the frequency of these sinusoidal stimuli is proportional to the velocity of rotation, rotation at low and moderately fast speeds allows the study of the mid-and low-frequency dynamics of these otolith-ocular reflexes. 2. Animals were rotated in complete darkness in the yaw, pitch, and roll planes at velocities ranging between 7.4 and 184 degrees/s. Accordingly, otolith-ocular reflexes (manifested as sinusoidal modulations in eye position and/or slow-phase eye velocity) were quantitatively studied for stimulus frequencies ranging between 0.02 and 0.51 Hz. During yaw and roll rotation, torsional, vertical, and horizontal slow-phase eye velocity was sinusoidally modulated as a function of head position. The amplitudes of these responses were symmetric for rotations in opposite directions. In contrast, mainly vertical slow-phase eye velocity was modulated during pitch rotation. This modulation was asymmetric for rotations in opposite direction. 3. Each of these response components in a given rotation plane could be associated with an otolith-ocular response vector whose sensitivity, temporal phase, and spatial orientation were estimated on the basis of the amplitude and phase of sinusoidal modulations during both directions of rotation. Based on this analysis, which was performed either for slow-phase eye velocity alone or for total eye excursion (including both slow and fast eye movements), two distinct response patterns were observed: 1) response vectors with pronounced dynamics and spatial/temporal properties that could be characterized as the low-frequency range of "translational" otolith-ocular reflexes; and 2) response vectors associated with an eye position modulation in phase with head position ("tilt" otolith-ocular reflexes). 4. The responses associated with two otolith-ocular vectors with pronounced dynamics consisted of horizontal eye movements evoked as a function of gravity along the interaural axis and vertical eye movements elicited as a function of gravity along the vertical head axis. Both responses were characterized by a slow-phase eye velocity sensitivity that increased three- to five-fold and large phase changes of approximately 100-180 degrees between 0.02 and 0.51 Hz. These dynamic properties could suggest nontraditional temporal processing in utriculoocular and sacculoocular pathways, possibly involving spatiotemporal otolith-ocular interactions. 5. The two otolith-ocular vectors associated with eye position responses in phase with head position (tilt otolith-ocular reflexes) consisted of torsional eye movements in response to gravity along the interaural axis, and vertical eye movements in response to gravity along the nasooccipital head axis. These otolith-ocular responses did not result from an otolithic effect on slow eye movements alone. Particularly at high frequencies (i.e., high speed rotations), saccades were responsible for most of the modulation of torsional and vertical eye position, which was relatively large (on average +/- 8-10 degrees/g) and remained independent of frequency. Such reflex dynamics can be simulated by a direct coupling of primary otolith afferent inputs to the oculomotor plant. (ABSTRACT TRUNCATED)     

The effects of computer interface design on human postural dynamics

The main objective of this study was to examine the effects of human-computer interface design on postural dynamics, i.e., changes in working postures and postural discomfort exhibited by operators of the computer-based remote bar coding (RBC) system. In addition, the effects of different work/rest schedules on postural dynamics were evaluated. Twelve subjects participated in the laboratory experiment, which consisted of twelve scenarios utilizing two cognitive task requirement factors, i.e., (1) information presentation mode, defined through the letter image preview on the computer screen (none or one preview image); and (2) the information processing mode, defined through the specific keying method (key all characters or key 5 digits only). The third experimental factor was the work/rest schedule (50 min work/10 min break, 2 h of work/15 min break, or flexible schedule). The results showed that requirements of human-computer interface design significantly affected the operators' postural dynamics. It was concluded that not only the physical, organizational, or psychosocial work environment characteristics, but also the cognitive task characteristics are important for assessment of postural effects in the VDT work. The relationship between interface design, mental workload and postural dynamics should be carefully considered in future studies aimed at optimizing the human-computer data entry tasks.     

Similar attentional, frequency, and associative effects for pseudohomophones and words

Between the presentation and recall of 1 or 5 digits, Ss performed a secondary task of naming a visually presented letter string--a pseudohomophone (e.g., FOLE, HOAP) or its real-word counterpart (FOAL, HOPE). Memory load interacted with frequency (HOPE vs. FOAL, HOAP vs. FOLE) but not with lexicality (HOPE vs. HOAP, FOAL vs. FOLE). This outcome counters models in which nonwords are named by a slow (resource-expensive) process that assembles phonology and words are named by a fast (resource-inexpensive) process that accesses lexical phonology. When the associative priming-of-naming task was secondary to the memory task, pseudohomophone associative priming (HOAP-DESPAIR, FOLE-HORSE) equaled associative priming (HOPE-DESPAIR, FOAL-HORSE) and was affected in the same way by memory load. Assembled phonology seems to underlie the naming of both words and nonwords.     

Automatic activation of phonological information in reading: evidence from the semantic relatedness decision task

A semantic relatedness decision task was used to investigate whether phonological recording occurs automatically and whether it mediates lexical access in visual word recognition and reading. In this task, subjects read a pair of words and decided whether they were related or unrelated in meaning. In Experiment 1, unrelated word-homophone pairs (e.g., LION-BARE) and their visual controls (e.g., LION-BEAN) as well as related word pairs (e.g., FISH-NET) were presented. Homophone pairs were more likely to be judged as related or more slowly rejected as unrelated than their control pairs, suggesting phonological access of word meanings. In Experiment 2, word-pseudohomophone pairs (e.g., TABLE-CHARE) and their visual controls (e.g., TABLE-CHARK) as well as related and unrelated word pairs were presented. Pseudohomophone pairs were more likely to be judged as related or more slowly rejected as unrelated than their control pairs, again suggesting automatic phonological recording in reading.     

Spatial System Dynamics: New Approach for Simulation of Water Resources Systems

A new approach called spatial system dynamics (SSD) is presented to model feedback based dynamic processes in time and space. This approach is grounded in control theory for distributed parameter systems. System dynamics and geographic information system (GIS) are coupled to develop this modeling approach. The SSD modeling approach offers a single modeling framework for developing conceptually different models. It also provides the much-needed capability to model feedback based complex dynamic processes in time and space while giving insight into the interactions among different components of the system. The proposed approach is superior to existing techniques for dynamic modeling such as cellular automata and GIS and addresses most of the limitations present in these approaches. The SSD approach can be used to model a variety of physical and natural processes where the main interest is the space–time interaction, e.g., environmental/water resources processes, natural resources management, climate change, and disaster management. The applicability of the proposed approach is demonstrated with an application to flood management in the Red River basin in Manitoba, Canada.