The role of duration and rapid temporal processing on the lateral perception of consonants and vowels

This study explored the extent to which rapid temporal processing and duration contribute to the right-ear advantage (REA) and presumably left-hemisphere processing for stop consonants and the lack of clear-cut laterality effects for vowels. Three sets of synthetic stimuli were constructed: consonant vowel stimuli [ba da ga bi di gi bu du gu] of 300 msec duration (full stimuli) and two shortened stimuli consisting either of a noise burst and 40-msec transitions (40-msec stimuli), or a noise burst and 20-msec transitions (20-msec stimuli). Stimuli were presented dichotically for consonant, vowel, and syllable identification. Results indicated a significant REA for consonants in the full and 40-msec conditions and a non-significant REA in the 20-msec condition. Nevertheless, the magnitude of laterality did not change across the three conditions. These results suggest that although transition information including duration contributes to lateralization for stop consonants, it is the presence of abrupt onsets which crucially determines lateralized processing. For vowels, there was a significant REA only in the full stimulus condition, and a significant decrement in the magnitude of the laterality effect in the two shortened stimulus conditions. These results suggest that for vowel perception, it is the nature of the acoustic cue used for phonetic identification and not duration that seems to be the critical determinant of lateralization effects.     

Avoidance extinction in goldfish

Independent groups of goldfish trained to avoid shock in a shuttlebox situation were presented with several extinction procedures in which the relationships between the conditioned stimulus and shock were altered and/or response contingencies removed. Random shock presentations, equivalent to the number of shocks received during avoidance acquisition, resulted in response decrements similar to those obtained when the conditioned stimulus was presented alone. Pairing the conditioned stimulus with shock on every trial, however, served to maintain response levels. When response-contingent punishment was superimposed upon these Pavlovian pairings, performance was facilitated slightly although punishment alone resulted in somewhat faster response reduction than that produced by exposure only to the conditioned stimulus. Extinction of avoidance responding produced by exposure to the conditioned stimulus alone was dependent on the total duration of exposure and independent of both number of stimulus onsets and response prevention. These experiments demonstrated that, in general, the procedures used to reduce avoidance responding in rats were equally effective for goldfish, with one exception: the introduction of a Pavlovian contingency following avoidance acquisition, making the previously avoidable shock unavoidable, maintained response probabilities near previously established levels.     

Problems in,and strategies for,evaluating preschool programs

Discusses the difficulty of documenting the effectiveness of preschool programs and relates this to the measuring instruments used and the type of design selected. The limitations of using standardized intelligence tests and the value of using cirterion-referenced tests are reviewed. A variety of methods are provided to assist psychologists and educators who are called upon to evaluate preschool programs. Three studies of preschool programs using different designs which involve published criterion-referenced tests are presented.