Effects of ontogeny on performance of rats in a novel object-recognition task

The current experiment investigated ontogenetic forgetting on a novel object-recognition task similar to that of Besheer and Bevins. 18-day-old pups (n = 49) and adult (n = 29) rats were tested at two retention intervals (1 min. or 120 min.). By employing exclusion criteria which demanded minimum amounts of object exploration at training and test, the performance of 18-day-old pups but not that of adults was significantly impaired at 120 min. relative to 1 min. Analysis indicated that the ontogeny of the learning and memory measured in novel object recognition follows a developmental trend similar to that of other forms of learning, with older animals remembering more and thus performing better than younger animals. Unfortunately, given the extreme variability inherent to the task and large N necessary to achieve significance, the use of this task in studies of learning, memory, and development is discouraged.     

Differential mastication kinematics of the rabbit in response to food and water: Implications for conditioned movement

Analysis of naturalistic chewing patterns may provide insight into mapping the neural substrates of jaw movement control systems, including their adaptive modification during the classically conditioned jaw movement (CJM) paradigm. Here, New Zealand White rabbits were administered food and water stimuli orally to evaluate the influence of stimulus consistency on masticatory pattern. Chewing patterns were recorded via video camera and movements were analyzed by computerized image analysis. The mandibular kinematics, specifically the extent of dorsal/ventral, medial/lateral, and rostral/caudal movement, were significantly larger in food-evoked than water-evoked chewing. Water-evoked chewing frequency, however, was significantly higher than that of food-evoked movements. In light of known cortical mastication modulatory centers, our findings implicate different neural substrates for the responses to food and water stimuli in the rabbit. A detailed delineation of jaw movement patterns and circuitry is essential to characterize the neural substrates of CJM.     

Reducing the drop-out rates of at-risk high school students: the Effective Learning Program (ELP)

The purpose of the present study was to evaluate the effectiveness of the Effective Learning Program (ELP) with students who are at high risk for dropping out of high school. The intervention sought to change external control expectancies to more internal ones, improve students' skills in building relationships with peers and adults, and increase graduation rates. Thirty-eight students considered at risk for dropping out of high school received the intervention. In addition, ELP-eligible students who did not receive the ELP intervention (n = 36) and regular education students (n = 50) from the same high school were compared with the students who received the ELP. A significantly greater percentage of ELP students graduated, became more internally controlled, achieved more as shown by standardized tests, and developed greater social skills and better relationships than their ELP-eligible but nonparticipating peers. The authors suggest that researchers identify which aspects of the ELP are responsible for the improvement in retention, achievement, and personal attributes.     

An outcome evaluation of the implementation of the Triple P-Positive Parenting Program in Hong Kong

The present study evaluated the effectiveness of the Positive Parenting Program (Triple P) with a sample of Chinese parents of children with early onset conduct-related problems in Hong Kong. The participants consisted of 91 parents whose children attended maternal and child health centers and child assessment centers for service, and were between three to seven years old. Participants were randomly assigned to the intervention (TP) and a waitlist control group (WL). There was no significant difference in pre-intervention measures between the two groups. However, at post intervention, participants in the TP group reported significantly lower levels of child behavior problems, lower dysfunctional parenting styles, and higher parent sense of competence, compared to the WL group. Implications of these findings for the use of Triple P with families of Chinese descent are discussed.     

Children's working-memory processes: a response-timing analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading-and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skill and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance.     

Facilitation and disruption of lateralized syllable processing by unattended stimuli in the opposite visual field

The influence of lateralized unattended stimuli on the processing of attended stimuli in the opposite visual field can shed light on the nature of information that is transferred between hemispheres. On a cued bilateral task, participants tried to identify a syllable in the attended visual field, which elicits a left hemisphere (LH) advantage and different processing strategies by the two hemispheres. The same or a different syllable or a neutral stimulus appeared in the unattended field. Transmission of unattended syllable codes between hemispheres is symmetric, as revealed by equal interference for the two visual fields. The LH is more accurate than the RH in encoding unattended syllables, as indicated by facilitation in the left but not right visual field and a greater frequency of identifiable intrusions into the left than right field. However, asymmetric encoding strategies are different for attended and unattended syllables.     

The neural basis of autobiographical and semantic memory: new evidence from three PET studies

A novel, neuropsychologically informed paradigm (extended retrieval of events in response to a cue word) was used to investigate the neural basis of autobiographical and semantic memory. Contrasting retrieval of autobiographical memories with retrieval of semantic facts (ABM-SEM) in 24 subjects across three PET studies revealed bilateral involvement of the middle temporal gyrus (BA 21) and medial frontal cortex (BA 9/10). The opposite contrast, SEM-ABM, resulted in increased regional cerebral blood flow in left posterior temporal regions (BA 37) and left prefrontal cortex (BA 45/46). Laterality maps suggest that the bilateral pattern seen in our studies, but not often in other neuroimaging investigations, reflects the use of a task stressing retrieval of specific personal events. Further comparisons revealed that the activation in the right anterior temporal lobe during autobiographical recall was virtually identical to that seen during retrieval of information about famous people or events in contrast with retrieval of general semantic facts. These findings suggest that the retrieval of an autobiographical event requires participation from conceptual knowledge, and that this type of knowledge is bilaterally distributed in the temporal lobes.     

Linguistically mediated visual search

During an individual's normal interaction with the environment and other humans, visual and linguistic signals often coincide and can be integrated very quickly. This has been clearly demonstrated in recent eyetracking studies showing that visual perception constrains on-line comprehension of spoken language. In a modified visual search task, we found the inverse, that real-time language comprehension can also constrain visual perception. In standard visual search tasks, the number of distractors in the display strongly affects search time for a target defined by a conjunction of features, but not for a target defined by a single feature. However, we found that when a conjunction target was identified by a spoken instruction presented concurrently with the visual display, the incremental processing of spoken language allowed the search process to proceed in a manner considerably less affected by the number of distractors. These results suggest that perceptual systems specialized for language and for vision interact more fluidly than previously thought.     

A computer-controlled olfactometer for fMRI and electrophysiological studies of olfaction

A design for an inexpensive and reliable olfactometer is presented. The design has several advantages for fMRI and electrophysiology investigators. These advantages include relatively rapid odorant rise times, computer control, multiple odor administration, and no ferrous materials near the subjects. In addition, the device is contamination resistant, and, because the air is neither warmed nor humidified, it is unlikely to become an incubator for bacteria. The olfactometer is constructed of off-the-shelf chromatography parts that require little modification.     

Reversing the phonological similarity effect

The phonological similarity effect--poor retention of order for lists of similar-sounding items--is a benchmark finding in the short-term memory literature. In our first two experiments, we show that the effect actually reverses following relatively brief periods of distraction, yielding better order retention for similar than for dissimilar lists, provided that different items are used on every trial. In Experiment 3, the same items were used on every trial and similar lists produced poorer performance across all three retention intervals. The results are interpreted from a general discrimination framework: Items are viewed as occupying positions in a multidimensional space defined by list and within-list dimensions.