Whose picture is this? Children's memory for item and source information

Children aged 3½ to 6½ years viewed pictures of common objects presented either once or three times on one of two consecutive days. A different hand puppet was used to present the pictures on each day, providing both perceptual and temporal cues to source. At test, old (studied) and new (non‐studied) pictures were presented for item recognition and source identification. Results showed that both item and source accuracy were higher for older (M = 5; 9 years) than younger children (M = 4; 6 years). Significant interactions between Age and Day of study were found for both item and source accuracy. For younger children, accuracy was higher for pictures studied on Day 1 than Day 2 (significant for source identification but not item recognition), whereas older children showed the opposite pattern: Higher accuracy for Day 2 than Day 1 (significant for item recognition but not source identification). Results are interpreted with respect to proactive interference and response bias. The utility of signal detection theory measures in determining the basis of age differences in performance of source identification is discussed.     

Basis of recency and frequency judgements of novel faces: Generalised strength or episode-specific memories?

Evidence for generalised and episode-specific strength in judgements of recency and frequency of novel faces was investigated in two experiments. Novel faces (created using an identikit program) were presented either once or three times in either of two study sets, separated by a 4 minute (Experiment 1) or 24 hour (Experiment 2) delay. In Experiment 2, the study–test phases were preceded by a familiarisation phase in which faces were presented either with or without an occupational label (some faces were not familiarised). In both experiments, judgements of recency were consistent with greater reliance on generalised strength (an amalgamation of recency and frequency of presentation), although there was some evidence for a contribution of episode-specific information. Familiarisation had opposite effects on judgements of recency and frequency, with familiarised faces judged as having been studied more frequently (three times), but less recently (yesterday) than unfamiliarised faces. The latter result is consistent with participants discounting generalised strength when episode-specific information is inadequate.     

Basis of recency and frequency judgements of novel faces: generalised strength or episode-specific memories?

Evidence for generalised and episode-specific strength in judgements of recency and frequency of novel faces was investigated in two experiments. Novel faces (created using an identikit program) were presented either once or three times in either of two study sets, separated by a 4 minute (Experiment 1) or 24 hour (Experiment 2) delay. In Experiment 2, the study-test phases were preceded by a familiarisation phase in which faces were presented either with or without an occupational label (some faces were not familiarised). In both experiments, judgements of recency were consistent with greater reliance on generalised strength (an amalgamation of recency and frequency of presentation), although there was some evidence for a contribution of episode-specific information. Familiarisation had opposite effects on judgements of recency and frequency, with familiarised faces judged as having been studied more frequently (three times), but less recently (yesterday) than unfamiliarised faces. The latter result is consistent with participants discounting generalised strength when episode-specific information is inadequate.     

Time of day modulation of conditioned place preference in rats depends on the strain of rat used

In golden hamsters, the expression of a conditioned place preference (CPP) or avoidance (CPA) is regulated in a circadian pattern such that the preference and avoidance are exhibited strongly at the circadian time of prior training, but not at other circadian times. In the rat, reports are conflicting regarding whether time of day learning is evident. We investigated whether this conflict arises because different strains of rat have been used. In this experiment, Long Evans and Wistar rats were trained at a specific circadian time to discriminate between a context paired with food reward and an unpaired context. Animals were then tested for preference at the same or a different circadian time. Long Evans rats showed preference for the paired context at both times tested, whereas Wistar rats showed preference only when training and testing times matched. The results show that time of day learning can be generalized to rats using the Wistar strain.     

Experimental manipulation of prior experience: Effects on item and associative recognition

Frequency of exposure to very low- and high-frequency words was manipulated in a three-phase (familiarisation, study, and test) design. During familiarisation, words were presented with their definition (once, four times, or not presented). One week (Experiment 1) or one day (Experiment 2) later, participants studied a list of homogeneous pairs (i.e., pair members were matched on background and familiarisation frequency). Item and associative recognition of high- and very low-frequency words presented in intact, rearranged, old-new, or new-new pairs were tested in Experiment 1. Associative recognition of very low-frequency words was tested in Experiment 2. Results showed that prior familiarisation improved associative recognition of very low-frequency pairs, but had no effect on high-frequency pairs. The role of meaning in the formation of item-to-item and item-to-context associations and the implications for current models of memory are discussed.     

Concurrent disjoint and reciprocal classification by Cebus apella in seriation tasks: evidence for hierarchical organization

We report the results of a 4-year-long study of capuchin monkeys (Cebus apella ) on concurrent three-way classification and linear size seriation tasks using explicit ordering procedures, requiring subjects to select icons displayed on touch screens rather than manipulate and sort actual objects into groups. The results indicate that C. apella is competent to classify nine items concurrently, first into three disjoint classes where class exemplars are identical to one another, then into three reciprocal classes which share common exemplar (size) features. In the final phase we compare the relative efficiency of executive control under conditions where both hierarchical and/or linear organization can be utilized. Whilst this shows a superiority of categorical based size seriation for a nine item test set suggesting an adaptive advantage for hierarchical over linear organization, Cebus nevertheless achieved high levels of principled linear size seriation with sequence lengths not normally achieved by children below the age of six years.