Temporal summation at the warmth threshold

Threshold levels for warmth aroused by infrared irradiation were measured in sLx Ss at durations between 0.05 and 10 sec. Beyond a critical duration of about a second, the threshold does not depend on duration. Below critical duration time t trades for irradiance ? by the formula ? = kt^?0.82. That these properties do not depend much on areal extent of stimulation was demonstrated by a study that compared temporal summation for two different areas of the same S’s skin. Individual differences in apparent absolute sensitivity were explored under the rubric of the theory of signal detection.     

A matching-to-sample procedure for the study of visual perception and concept formation in infrahumans: A test in the pigeon

An apparatus suitable for conducting simultaneous or delayed matching-to-sample experiments with as many as eight comparison stimuli is described. Data are presented which indicate that pigeons are capable of performing such a task. It is concluded that the simultaneous matching-to-sample procedure with more than two comparison stimuli is an efficient means of obtaining information about discrimination capacity and that this procedure may be suitable for studying visual perception in infrahuman Ss.     

Children's component selection with varying degrees of training

With the component selection measure developed by Hale and Morgan (1973), children's use of selective attention was assessed at six levels of learning, ranging from undertraining to overtraining, and this function was examined at each of ages 4, 8, and 12. It was found that, as the children learned the task, they maintained a relatively wide focus of attention, acquiring information about both features of the stimuli, color and shape. Thus, contrary to the model under investigation, the children did not exercise a high degree of selectivity as they approached mastery of the task; nor did overtraining produce the expected “broadening” of attention, as the children acquired little stimulus information beyond the point at which criterion had been reached. The data were interpreted to be more consistent with a model that assumes the bulk of stimulus learning to occur prior to task mastery.     

On the form of learning curves

In a wide variety of learning experiments, cumulated measures of performance turn out to be a power function of practice time or number trials, typically with an exponent between 1 and 2. The effects of various conditions on the course of learning can frequently be described in terms of the two constants of the function.     

Child‐directed teaching and social learning at 18 months of age: evidence from Yucatec Mayan and US infants

In several previous studies, 18‐month‐old infants who were directly addressed demonstrated more robust imitative behaviors than infants who simply observed another's actions, leading theorists to suggest that child‐directed interactions carried unique informational value. However, these data came exclusively from cultural communities where direct teaching is commonplace, raising the possibility that the findings reflect regularities in infants' social experiences rather than responses to innate or a priori learning mechanisms. The current studies consider infants' imitative learning from child‐directed teaching and observed interaction in two cultural communities, a Yucatec Mayan village where infants have been described as experiencing relatively limited direct instruction (Study 1) and a US city where infants are regularly directly engaged (Study 2). Eighteen‐month‐old infants from each community participated in a within‐subjects study design where they were directly taught to use novel objects on one day and observed actors using different objects on another day. Mayan infants showed relative increases in imitative behaviors on their second visit to the lab as compared to their first visit, but there was no effect of condition. US infants showed no difference in imitative behavior in the child‐directed vs. observed conditions; however, infants who were directly addressed on their first visit showed significantly higher overall imitation rates than infants who observed on their first visit. Together, these findings call into question the idea that child‐directed teaching holds automatic or universal informational value.     

Source Monitoring and Executive Function in 2.5- to 3-Year-Olds

Hala, Brown, McKay, and San Juan (2013) found that children as young as 2.5 years of age demonstrated high levels of accuracy when asked to recall whether they or the experimenter had carried out a particular action. In the research reported here, we examined the relation of early-emerging source monitoring to executive function abilities. Participants were children aged 2.5- to 3-years old. For the source-monitoring procedure, we used the Hala et al. (2013) task in which children and the experimenter took turns placing a total of 20 items on a model farm (encoding phase). For the source memory test, children were asked who had placed each item (retrieval phase). Executive function measures included assessments of working memory, delay-inhibitory control, and conflict-inhibitory control. The main finding was that inhibitory control measures were significantly related to performance on the source-monitoring task. This relation held for the conflict-inhibitory control measures even when controlling for age and vocabulary. The findings of this research suggest that even at the early age of 2.5 years, development of executive control is linked to the emergence of source-monitoring ability.     

Statistical Learning Is Not Affected by a Prior Bout of Physical Exercise

This study examined the effect of a prior bout of exercise on implicit cognition. Specifically, we examined whether a prior bout of moderate intensity exercise affected performance on a statistical learning task in healthy adults. A total of 42 participants were allocated to one of three conditions—a control group, a group that exercised for 15 min prior to the statistical learning task, and a group that exercised for 30 min prior to the statistical learning task. The participants in the exercise groups cycled at 60% of their respective O₂max. Each group demonstrated significant statistical learning, with similar levels of learning among the three groups. Contrary to previous research that has shown that a prior bout of exercise can affect performance on explicit cognitive tasks, the results of the current study suggest that the physiological stress induced by moderate‐intensity exercise does not affect implicit cognition as measured by statistical learning.