This paper examines the concept of availability and its theoretical role in the cognitive processes. An item's availability (AV) is operationally defined by the probability that S could recall it after a 15-sec delay. (AV seems to grow fastest when S produces it from memory. It also grows, though not as fast, when S sees the item without producing it.) This definition is used to examine the principle of associative symmetry, and evidence is presented to support it. Sources of asymmetry in natural language are examined, and the concept's theoretical implications for memory and though are discussed. (38 ref.)

Neural responses evoked by the same binaural speech signal were recorded from ten right-handed subjects during two auditory identification tasks. One task required analysis of acoustic parameters important for making a linguistic distinction, while the other task required analysis of an acoustic parameter which provides no linguistic information at the phoneme level. In the time interval between stimulus onset and the subjects' identification responses, evoked potentials from the two tasks were significantly different over the left hemisphere but identical over the right hemisphere. These results indicate that different neural events occur in the left hemisphere during analysis of linguistic versus nonlinguistic parameters of the same acoustic signal.

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