Exploring the space of cognitive architectures

Production systems have been proposed as a candidate for the basic architecture of the human information processor. We consider a number of dimensions along which production systems can vary, and we discuss PRISM, a production system formalism designed to aid cognitive modelers in their exploration of the space of architectures. Examples of PRISM settings are presented in the context of particular models. Finally, some heuristics are suggested for efficiently searching the space of possible architectures.     

Violence Exposure and PTSD: The Role of English Language Fluency in Latino Youth

Although Latinos have been a rapidly growing population in the US, little is known about how mental health symptoms may present in Latino children especially in the context of those living in poverty and exposed to violence. We explored the level of violence exposure and trauma symptoms in Latino youth and the relationship of these factors with English language fluency. During 2000–2002, 1,601, Latino students from seven middle schools participated in a school-based screening to identify students with exposure to community violence and symptoms of Posttraumatic Stress Disorder (PTSD). The students completed a self-report instrument, in either Spanish or English, that combined a modified version of the Life Events Scale and the Child PTSD Symptom Scale (CPSS). Bivariate analyses and multivariate regression models showed that youth with higher English language fluency reported greater violence exposure and PTSD symptoms than those with lower fluency. No difference was found in functioning by English language fluency. English language fluency appears to be related to violence exposure and PTSD symptoms in these Latino youth. We discuss the importance of school-based programs especially designed to serve Latino students of varying English language fluency.     

The Acquisition of Time Properties Associated with a Sequential Motor Skill

Three experiments are reported that examined the relative importance of phasing and duration training in the motor learning of a sequential task. In all three experiments, the task involved knocking down three barriers in a specified order. The Phasing task required the subject to contact each of the barriers in a particular goal time interval, that is, each segment had a particular movement-time goal. The Duration task required the subject to contact the final barrier in a total elapsed-time goal defined by the experimenter. Following training, half of the subjects in each training condition transferred to either a novel Duration or a novel Phasing task. Phasing-trained subjects, compared to Duration-trained subjects, produced equivalent transfer performance on the Duration transfer task but superior performance on the Phasing transfer task. These results suggest that phasing serves as a higher-order source of information for the performer in a sequential motor task. In addition, these experiments complement and extend previous work by Shapiro (1977) and Summers (1975) which demonstrated that learned phasing patterns were not modified despite changes in the overall rate of performing a motor sequence. Our experiments indicate that phasing training increases the performer’s sensitivity to phasing patterns such that novel temporal patterns can be produced when they are well-defined.     

Doggone affordances: Canine perception of affordances for reaching

Performing any behavior requires perceiving affordances—whether and how that behavior can be performed. Perception of affordances exhibits action scaling—choices about when to transition between two different modes of behavior reflect the fit between action capabilities and environmental properties. The boundary between distances that are perceived to be reachable with an arm-only reach and those that are perceived to be reachable with an arm-plus-torso reach occurs at farther distances for long-armed than for short-armed people, but at the same ratio of object-distance-to-arm length for both groups. To the extent that perception of affordances is supported by detection of invariant stimulation patterns, perception of a given affordance ought to exhibit action scaling regardless of species. We investigated the heights at which dogs chose to transition from reaching with the head only to rearing (i.e., reaching with the head plus torso). This transition occurred at a taller height for tall than for short dogs, but at the same ratio of shoulder-height-to-treat-height for both groups. The results demonstrate a similarity in perception of affordances across species and suggest that perception of affordances is supported by detection of lawfully structured stimulation patterns that may be invariant across species.     

A novel continuous inhibitory-control task: variation in individual performance by young pheasants (<Emphasis Type="Italic">Phasianus colchicus</Emphasis>)

Inhibitory control enables subjects to quickly react to unexpectedly changing external demands. We assessed the ability of young (8 weeks old) pheasants Phasianus colchicus to exert inhibitory control in a novel response-inhibition task that required subjects to adjust their movement in space in pursuit of a reward across changing target locations. The difference in latencies between trials in which the target location did and did not change, the distance travelled towards the initially indicated location after a change occurred, and the change-signal reaction time provided a consistent measure that could be indicative of a pheasant’s inhibitory control. Between individuals, there was a great variability in these measures; these differences were not correlated with motivation either to access the reward or participate in the test. However, individuals that were slower to reach rewards in trials when the target did not change exhibited evidence of stronger inhibitory control, as did males and small individuals. This novel test paradigm offers a potential assay of inhibitory control that utilises a natural feature of an animal’s behavioural repertoire, likely common to a wide range of species, specifically their ability to rapidly alter their trajectory when reward locations switch.     

The Socialization of Children’s Memory: Linking Maternal Conversational Style to the Development of Children’s Autobiographical and Deliberate Memory Skills

Data from a large-scale, longitudinal research study with an ethnically and socioeconomically diverse sample were utilized to explore linkages between maternal elaborative conversational style and the development of children’s autobiographical and deliberate memory. Assessments were made when the children were aged 3, 5, and 6 years old, and the results reveal concurrent and longitudinal linkages between maternal conversational style in a mother–child reminiscing task and children’s autobiographical memory performance. Maternal conversational style while reminiscing was also significantly related to children’s strategic behaviors and recall in 2 deliberate memory tasks, both concurrently and longitudinally. Results from this examination replicate and extend what is known about the linkages between maternal conversational style, children’s abilities to talk about previous experiences, and children’s deliberate memory skills as they transition from the preschool years to early elementary school years.     

The stereoscopic anisotropy: individual differences and underlying mechanisms

Observers are more sensitive to variations in the depth of stereoscopic surfaces in a vertical than in a horizontal direction; however, there are large individual differences in this anisotropy. The authors measured discrimination thresholds for surfaces slanted about a vertical axis or inclined about a horizontal axis for 50 observers. Orientation and spatial frequency discrimination thresholds were also measured. For most observers, thresholds were lower for inclination than for slant and lower for orientation than for spatial frequency. There was a positive correlation between the 2 anisotropies, resulting from positive correlations between (a) orientation and inclination thresholds and (b) spatial frequency and slant thresholds. These results support the notion that surface inclination and slant perception is in part limited by the sensitivity of orientation and spatial frequency mechanisms.     

Contrast adaptation implies two spatiotemporal channels but three adapting processes

The contrast gain control model of adaptation predicts that the effects of contrast adaptation correlate with contrast sensitivity. This article reports that the effects of high contrast spatiotemporal adaptors are maximum when adapting around 19 Hz, which is a factor of two or more greater than the peak in contrast sensitivity. To explain the discrepancy, the predictions made by parallel versus cascaded models of spatiotemporal processing are compared. It is demonstrated that a parallel two-temporal channel model, in which the adaptive attenuation of a channel is proportional to its response, cannot explain the effects of adaptation on threshold contrast but that a cascaded model can. The cascaded model suggests that the visual system temporally encodes spatiotemporal signals via an adaptive transient encoding process that lies in cascade with an adaptable two-temporal channel system of sustained versus transient processes.     

On the use of wireless response systems in experimental psychology: Implications for the behavioral researcher

A method of data collection is presented that unites the efficiency of mass testing with the ease of instant electronic data collection that is typical of computer-based experiments run on individual participants. A wireless response system (WRS), originally designed as a teaching tool, is used to replicate three classic and robust effects from the memory literature (effects of false memory, levels of processing, and word frequency). It is shown that for these types of experimental designs, data can be collected more efficiently (in both time and effort) with the WRS method than through traditional mass- and individual-testing methods alone. The advantages and limitations of WRSs for use in mass electronic data collection are discussed.