Results from several letter- and digit-identification studies have been interpreted (Appelman & Mayzner, 1982; Krumhansl, 1982) as providing support for the hypothesis that psychological similarity is influenced by the local density of items in the stimulus space. This conclusion is questioned on the grounds that density was not directly manipulated in the studies, thus alternative explanations...

Results from three studies are reported in which adults between 18 and 84 years of age performed various versions of the Digit Symbol Substitution Test. The first study revealed that the age-related declines in digit-symbol performance were largely independent of both the amount of education the participants had received and their self-reported health status, and were characterized by a gradual...

A novel hybrid number representation is proposed in this paper. It includes the two's complement representation and the signed-digit mpresentation as special cases. The hybrid number representations proposed are capable of bounding the maximum length of carry propagation chains during addition to any desired value between 1 and the entire word length. The framework reveals a continuum of number...

In neuropsychological practice, the availability of effective and reliable tests is crucial. The Symbol Digit Modalities Test (SDMT) is widely used because it is easy to administer, reliable and also evaluates information processing speed. We set out to obtain normative data (currently unavailable for the Italian population) for the oral version of this test. Both age and education influenced p...

Past research has examined the contribution of mediator-based encoding strategies (interactive imagery and sentence generation) to individual (particularly age-related) differences in associative memory exclusively in the paired-associates paradigm. In the present study, we examined young and older adults' mediator-based strategy use on source-monitoring tasks. Participants spontaneously used m...

Coherence of neural activity between circumscribed brain regions has been implicated as an indicator of intracerebral communication in various cognitive processes. While neural activity can be volitionally controlled with neurofeedback, the volitional control of coherence has not yet been explored. Learned volitional control of coherence could elucidate mechanisms of associations between cortic...