Localization of sound sources outside the median plane is influenced primarily by differences in head shadow and arrival time of the signal at the two ears of the observer. For sources located within this plane, localization is influenced primarily by the irregularities of the pinna. By progressively occluding these cavities, it is shown that localization ability decreases with increasing occlusion, that it is better for signals in the anterior than in the posterior sector of the median plane, and that high-frequency signal content is more important than the low. A number of hypotheses regarding localization in the median plane are noted.

Autobiographical memory (AM), the recollection of past experiences, and prospective memory (PM), the prospection of future events, are prominent components of subjective life, yet data on the frequencies of their occurrence are limited. Using experience sampling, we quantified the incidence of AM and PM in natural settings among various age groups. Individuals of all ages reported engaging in AM approximately 10% of the time. In contrast, whereas younger subjects recalled PMs as often as they recalled AMs, older subjects experienced PM twice as frequently. AM occurrence was positively correlated with PM occurrence, most strongly among younger individuals. AM and PM durations were also positively correlated and remarkably stable across age groups. Together, these data identify an age-associated shift in the temporal orientation of recollection and quantify the relationship between AM and PM. More broadly, this approach provides a quantitative foundation of AM and PM occurrence, a crucial yet largely unexplored dimension of recollection.

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Autobiographical memory (AM), subjective recollection of past experiences, is fundamental in everyday life. Nevertheless, characterization of the spontaneous occurrence of AM, as well as of the number and types of recollected details, remains limited. The CRAM (Cue-Recalled Autobiographical Memory) test (http://cramtest.info) adapts and combines the cue-word method with an assessment that collects counts of details recalled from different life periods. The SPAM (Spontaneous Probability of Autobiographical Memories) protocol samples introspection during everyday activity, recording memory duration and frequency. These measures provide detailed, naturalistic accounts of AM content and frequency, quantifying essential dimensions of recollection. AM content (∼20 details/recollection) decreased with the age of the episode, but less drastically than the probability of reporting remote compared to recent memories. AM retrieval was frequent (∼20/hour), each memory lasting ∼30 seconds. Testable hypotheses of the specific content retrieved in a fixed time from given life periods are presented.