Absence of overshadowing and blocking between landmarks and the geometric cues provided by the shape of a test arena

In three experiments rats were required to escape from a pool of water by swimming to a submerged platform. The position of the platform was determined by the shape of the pool, which was either rectangular or triangular. A landmark that was located on the surface of the pool near the platform failed to overshadow (Experiment 1) or block (Experiment 2) learning about the position of the platform with reference to the shape of the pool. Experiment 3 revealed a similar outcome with cues outside the pool, which could be used, in addition to the shape of the pool, to identify the location of the platform. These findings imply that theories of learning that assume that stimuli must compete with each other for the control that they acquire may not apply to spatial learning based on the shape of the environment.     

The relationships between quantity‐number competencies,working memory,and phonological awareness in 5‐ and 6‐year‐olds

In this study, the interdependencies among phonological awareness, verbal working memory components, and early numerical skills in children 1 year before school entry are addressed. Early numerical skills were conceptualized as quantity‐number competencies (QNC) at both basic (QNC Level 1) and advanced (QNC Level 2) levels. In a sample of 1,343 children aged 5 and 6, structural equation modelling provided support for the isolated number words hypothesis (Krajewski & Schneider, 2009, J. Exp. Child Psychol., 103, 516–531). This hypothesis claims that phonological awareness contributes to the acquisition of QNC Level 1, such as learning the number word sequence, but not of QNC Level 2, which requires the linkage of number words to quantities. In addition, phonological awareness relied on verbal working memory, especially with regard to the phonological loop, central executive, and episodic buffer. The results were congruent with the idea that phonological awareness mediates the impact of verbal working memory on QNCs. The relationships between verbal working memory, phonological awareness, and QNCs were comparable in monolingual and bilingual children.     

Summation in Autoshaping with Short- and Long-duration Stimuli

Five autoshaping experiments with pigeons examined the effects of presenting in compound two stimuli that had individually been paired with food. The rate of responding during the compound was the same as for the individual stimuli when the stimulus duration was 10 sec. When the duration of the stimuli was 30 sec, the compound elicited a higher response rate than its components. This enhanced rate of responding during the compound was evident only for the initial portion of each trial. Moreover, the enhanced rate of responding was no greater than for a compound composed of an excitatory and a neutral element. These results present difficulties for both elemental and configural theories of conditioning.