Visual routines for extracting magnitude relations

Linking relations described in text with relations in visualizations is often difficult. We used eye tracking to measure the optimal way to extract such relations in graphs, college students, and young children (6- and 8-year-olds). Participants compared relational statements (“Are there more blueberries than oranges?”) with simple graphs, and two systematic patterns emerged: eye movements that followed the verbal order of the question (inspecting the “blueberry” value first) versus those that followed a left-first bias (regardless of the left value’s identity). Question-order patterns led substantially to faster responses and increased in prevalence with age, whereas the left-first pattern led to far slower responses and was the dominant strategy for younger children. We argue that the optimal way to verify a verbally expressed relation’s consistency with visualization is for the eyes to mimic the verbal ordering but that this strategy requires executive control and coordination with language.     

The influence of adaptation and stochastic fluctuations on spontaneous perceptual changes for bistable stimuli

Spontaneous perceptual change was studied by measuring the probabilities of the first two spontaneous pattern switches as a function of time following the onset of a bistable apparent quartet for which either horizontal or vertical motion is perceived. Contrary to the classical satiation hypothesis (Köhler & Wallach, 1944),differential time-dependent adaptation of the perceived compared with the unperceived motion directions was not necessary to account for the first spontaneous switch. In addition, adaptation of the perceived motion accompanied by recovery from adaptation of the unperceived motion was not necessary to account for the increased probability of the second spontaneous switch. It was concluded that regardless of possible adaptation effects, stochastic fluctuations are necessary for the actual reversal of activation levels that produces the spontaneous switch. When the difference in detector activation is reduced by differential adaptation of competing motion detectors (or by the occurrence of a prior spontaneous pattern change), smaller stochastic fluctuations are sufficient to reverse the relative activation of competing detectors. Thus, adaptation can increase the probability of spontaneous switches without directly causing them.     

A Mid-Career Perspective on the Opportunity-Structure/Occupational-Choice Debate

Research into mid-career change lends support to K. Roberts' thesis on the significance of the opportunity structure for initial entry to work and during the early working years. Whether objective or 'socially constructed', it was perceived as a determinant by men who were ensuring that their children should not be constrained as they had been. The study also offers evidence of the subsequent strengthening and implementation of the self-concept and of a consequent change in the significance of the opportunity structure. The conclusions, highlighted in a case-history, tend to support all parties to the opportunity-structure/occupational-choice debate so far. They suggest that in today's turbulent environment there is an urgent need for careers information, guidance and counselling throughout working life.     

Weight, restraint, cognitions and counterregulation

An experiment was designed to examine restraint theory's assumptions that restraint is a more fundamental variable than weight, that counterregulatory behavior typifies the obese, and that cognitive factors play a role in counterregulation. The findings of this experiment were examined along with reanalyses of data from two additional studies of restraint (Hibscher and Herman, 1977; Spencer and Fremouw, 1979). The data indicated that restraint is a powerful predictor of consummatory patterns. However, there was no support for restraint theory's assumptions that counterregulatory behavior is prevalent among obese and that the confound between weight and restraint can completely account for obese-normal differences in behavior. The theory's assumption that cognitive factors influence counterregulatory (and regulatory) behavior was consistent with the findings.     

Sources of Resistance to Mergers Between Groups1

Workers involved in a business merger often display strong ingroup/outgroup biases that can threaten the merger's success. Social identity theory helps to explain why and when such problems will occur. Using that theory, strong cohesion and successful performance were identified as two characteristics of a workgroup that should increase its resistance to a merger. An experiment involving mergers between small task groups was conducted to test this claim. Each group's cohesion and performance was used to predict its enthusiasm for a merger before it occurred, and any ingroup/outgroup biases that it displayed afterwards. Cohesion was unrelated to either of these measures, but as we predicted, more successful groups were less enthusiastic and displayed stronger biases. Relative rather than absolute success was an especially good predictor of merger resistance. The results were discussed within the context of social identity theory, which generated several suggestions for further research on business mergers.     

Estimation of a Latent Variable Regression Growth Curve Model for Individuals Cross-Classified by Clusters

The cross-classified multiple membership latent variable regression (CCMM-LVR) model is a recent extension to the three-level latent variable regression (HM3-LVR) model which can be utilized for longitudinal data that contains individuals who changed clusters over time (for instance, student mobility across schools). The HM3-LVR model can include the initial status on growth effect as varying across those clusters and allows testing of more flexible hypotheses about the influence of initial status on growth and of factors that might impact that relationship, but only in the presence of pure clustering of participants within higher-level units. This Monte Carlo study was conducted to evaluate model estimation under a variety of conditions and to measure the impact of ignoring cross-classified data when estimating the incorrectly specified HM3-LVR model in a scenario in which true values for parameters are known. Furthermore, results from a real-data analysis were used to inform the design of the simulation. Overall, it would be recommended for researchers to utilize the CCMM-LVR model over the HM3-LVR model when individuals are cross-classified, and to use a bare minimum of more than 100 clustering units in order to avoid overestimation of the level-3 variance component estimates.     

Timing strategies used in defensive blinking to optical collisions in 5- to 7-month-old infants

When objects approach on a collision course, young babies will blink to protect their eyes. The timing of the blink is crucial, since it serves to protect the eyes from being injured. The image of a looming virtual object approached infants under different constant velocities and constant accelerations. The youngest infants (5–6 months) blinked when the image of the virtual object reached a threshold visual angle, while older infants (6–7 months) geared their blinks to the image’s time-to-collision. Infants using a strategy based on time coped successfully with all approach conditions, while infants using a strategy based on visual angle had difficulty with the fastest accelerative approach condition. The findings indicate that infants around 6 months of age shift to a more sophisticated strategy based on time, allowing them to deal with more demanding perceptual tasks.     

Individual and collective problem-solving in a foraging context in the leaf-cutting ant Atta colombica

In this paper we investigate the flexibility of foraging behavior in the leaf-cutting ant Atta colombica, both at the individual and collective levels, following a change in the physical properties of their environment. We studied in laboratory conditions the changes occurring in foraging behavior when a height constraint was placed 1 cm above part of the trail linking the nest to the foraging area. We found that the size and shape of the fragments of foraging material brought back to the nest were significantly modified when the constraint was placed on the trail: independent of their size, forager ants cut smaller and rounder fragments in the presence of a height constraint than in its absence. This size adjustment does not require any direct sensory feedback because it occurred when the ants cut fragments in the foraging area; no further cutting was done when they encountered the constraint. This points to the existence of a template that ants store and use as a reference to adjust their reach while cutting. Remarkably, despite the decrease in the foraging material brought to the nest per capita the colony was still able to improve its foraging performance by doubling the number of transporters. This study illustrates the flexibility of foraging behavior exhibited by an ant colony. It provides a rare example of insects finding an intelligent solution to a problem occurring in a foraging context, at both the individual and collective levels.