The role of edges in object recognition by pigeons

In three experiments, we explored how pigeons use edges, corresponding to orientation and depth discontinuities, in visual recognition tasks. In experiment 1, we compared the pigeon's ability to recognize line drawings of four different geons when trained with shaded images. The birds were trained with either a single view or five different views of each object. Because the five training views had markedly different appearances and locations of shaded surfaces, reflectance edges, etc, the pigeons might have been expected to rely more on the orientation and depth discontinuities that were preserved over rotation and in the line drawings. In neither condition, however, was there any transfer from the rendered images to the outline drawings. In experiment 2, some pigeons were trained with line drawings and shaded images of the same objects associated with the same response (consistent condition), whereas other pigeons were trained with a line drawing and a shaded image of two different objects associated with the same response (inconsistent condition). If the pigeons perceived any correspondence between the stimulus types, then birds in the consistent condition should have learned the discrimination more quickly than birds in the inconsistent condition. But, there was no difference in performance between birds in the consistent and inconsistent conditions. In experiment 3, we explored pigeons' processing of edges by comparing their discrimination of shaded images or line drawings of four objects. Once trained, the pigeons were tested with planar rotations of those objects. The pigeons exhibited different patterns of generalization depending on whether they were trained with line drawings or shaded images. The results of these three experiments suggest that pigeons may place greater importance on surface features indicating materials, such as food or water. Such substances do not have definite boundaries cued by edges which are thought to be central to human recognition.     

Fractionating working memory: consolidation and maintenance are independent processes

In the present study, we required subjects to remember simple objects that were masked to interrupt consolidation and allow us to estimate the rate of information accrual in visual working memory. We compared a consolidation-baseline condition with a consolidation-during-maintenance condition in which subjects needed to remember a set of unmasked items and then were shown to-be-remembered masked items. We hypothesized that if the control processes of consolidation and maintenance are performed by common mechanisms, then consolidation should be less efficient when performed during maintenance than when performed alone. However, we found that an identical amount of information was encoded per unit time in the two conditions. These results indicate that working memory consolidation is not slowed by maintenance and suggest a two-step model of encoding in visual working memory.     

Disseminating a smokeless tobacco cessation intervention model to dental hygienists: a randomized comparison of personalized instruction and self-study methods.

This study evaluated 2 methods of disseminating an empirically validated smokeless tobacco intervention delivered during routine dental care. Twenty cities within 12 states were stratified and then randomized to 1 of 3 groups: personalized instruction (PI), self-study (SS), or delayed training (DT) control. Dental hygienists in the SS condition were sent a manual and video. Those in the PI condition were recruited to attend a workshop. Thirty-seven percent of eligible hygienists agreed to participate. At 12 months postenrollment, hygienists in the SS and PI conditions significantly increased their "Assist" behaviors (discuss cessation techniques, help patient set a quit date, and provide cessation materials) and reported fewer perceived barriers to delivering the intervention as compared with hygienists in DT. An economic analysis suggests that SS is more cost-effective than PI.     

Assessing aggression in adolescent romantic relationships: can we do it better?

Almost all research on aggression in adolescent romantic relationships makes use of 1-time, retrospective assessment methods. In the present research, the authors compared data on the experience of adolescent relationship aggression (physical aggression and threatening behavior) collected from 125 high school students via 2 methods: (a) a 1-time, 2-month retrospective assessment and (b) a cumulative method based on four 2-week retrospective assessments, each spaced 2 weeks apart. For the cumulative method, data from the 4 assessments were aggregated to cover the same time period as the single, 2-month retrospective assessment. A greater proportion of the sample (48.0%) reported experiencing physical aggression using the cumulative method compared with the single, 2-month retrospective method (27.0%). The prevalence of threatening behavior was also higher using the cumulative method (48.8% vs. 24.8%). Adolescent trauma and anxiety symptoms correlated more strongly with physical aggression data derived from the cumulative method than from the 1-time assessment method.     

New approaches to demystifying insight

After a person has become stuck on a problem, they sometimes achieve a clear and sudden solution through insight--the so-called Aha! experience. Because of its distinctive experience, the origins and characteristics of insight have received considerable attention historically in psychological research. However, despite considerable progress in characterizing insight, the underlying mechanisms remain mysterious. We argue that research on insight could be greatly advanced by supplementing traditional insight research, which depends on a few complex problems, with paradigms common in other domains of cognitive science. We describe a large set of mini-insight problems to which multiple methods can be applied, together with subjective reports to identify insight problem-solving. Behavioral priming and neuroimaging methods are providing evidence about what, where, and how neural activity occurs during insight. Such evidence constrains theories of component processes, and will help to demystify insight.     

Means-means-end tool choice in cotton-top tamarins (Saguinus oedipus): finding the limits on primates’ knowledge of tools

Most studies of animal tool use require subjects to use one object to gain access to a food reward. In many real world situations, however, animals perform more than one action in sequence to achieve their goals. Of theoretical interest is whether animals have the cognitive capacity to recognize the relationship between consecutive action sequences in which there may be one overall goal and several subgoals. Here we ask if cotton-top tamarins, a species that in captivity uses tools to solve means-end problems, can go one step further and use a sequence of tools (means) to obtain food (end). We first trained subjects to use a pulling tool to obtain a food reward. After this initial training, subjects were presented with problems in which one tool had to be used in combination with a second in order to obtain food. Subjects showed great difficulty when two tools were required to obtain the food reward. Although subjects attended to the connection between the tool and food reward, they ignored the physical connection between the two tools. After training on a two-tool problem, we presented subjects with a series of transfer tests to explore if they would generalize to new types of connections between the tools. Subjects readily transferred to new connections. Our results therefore provide the first evidence to date that tamarins can learn to solve problems involving two tools, but that they do so only with sufficient training.     

Toward a taxonomy of attention shifting: Individual differences in fMRI during multiple shift types

Although task switching is often considered one of the fundamental abilities underlying executive functioning and general intelligence, there is little evidence that switching is a unitary construct and little evidence regarding the relationship between brain activity and switching performance. We examined individual differences in multiple types of attention shifting in order to determine whether behavioral performance and fMRI activity are correlated across different types of shifting. The participants (n=39) switched between objects and attributes both when stimuli were perceptually available (external) and when stimuli were stored in memory (internal). We found that there were more switchrelated activations in many regions associated with executive control—including the dorsolateral and medial prefrontal and parietal cortices—when behavioral switch costs were higher (poor performance). Conversely, activation in the ventromedial prefrontal cortex (VMPFC) and the rostral anterior cingulate was consistently correlated with good performance, suggesting a general role for these areas in efficient attention shifting. We discuss these findings in terms of a model of cognitive-emotional interaction in attention shifting, in which reward-related signals in the VMPFC guide efficient selection of tasks in the lateral prefrontal and parietal cortices.