Visual long-term memory for spatial frequency?

It has been suggested that a visual long-term memory based on a sensory representation of the stimulus accounts for discrimination performance when the reference and the test stimuli are separated in time. Decision processes involved in setting response criteria, however, may also contribute to discrimination performance. In the present study, it is shown that under proper control, spatial frequency discrimination thresholds from a group of observers, each performing on a single trial, are significantly higher for a 2-h than for a 5-sec retention interval, whereas thresholds from individual observers performing in repeated trials with a 2-h retention interval are considerably lower. The results suggest that discrimination performance may depend on the retention of task-relevant information, such as a response criterion, rather than on visual memory of the stimulus. It is concluded that it is risky to postulate ahigh-fidelity long-term visual memory for spatial frequency on the basis of psychophysical group discrimination thresholds.     

Working and long-term memory deficits in schizophrenia: is there a common prefrontal mechanism?

This study tested the hypothesis that dorsolateral prefrontal cortex deficits contribute to both working memory and long-term memory disturbances in schizophrenia. It also examined whether such deficits were more severe for verbal than nonverbal stimuli. Functional magnetic resonance imaging was used to assess cortical activation during performance of verbal and nonverbal versions of a working memory task and both encoding and recognition tasks in 38 individuals with schizophrenia and 48 healthy controls. Performance of both working memory and long-term memory tasks revealed disturbed dorsolateral prefrontal cortex activation in schizophrenia, although medial temporal deficits were also present. Some evidence was found for more severe cognitive and functional deficits with verbal than nonverbal stimuli, although these results were mixed.     

Does immediate imitation influence long-term memory for observed actions?

Long-term memory for object-related information acquired observationally was studied among younger and older toddlers under two conditions of acquisition and retention: direct imitation followed by reproduction after a 10 min delay (delayed imitation), and deferred imitation. A principal aim was to determine whether direct imitation fosters a form of enactive representation that improves long-term memory, or whether such memory is influenced more by visual encoding factors. Tasks consisted of five simple action combinations or separations. Results indicated that post-test scores were higher under all three post-test conditions than under pretest. Likewise, post-test performance was higher than that of a comparison group that did not observe the target actions. The results overall indicate that direct imitation did not operate substantially to improve memory for the modelled acts. Children were able to encode and retain about as much from their visual pickup of the modeled acts as from feedback obtained through the process of imitation. This finding was especially true for the older children.     

Is there a memory for sentences?

A critical discussion of the model of sentence memory which enjoyed greatest popularity in the psycholinguistic research of the sixties, namely the model based on the deep-structure-plus-tag hypothesis of sentence memory, is presented together with the results of an experiment on prompted recall for sentences with various intervals after presentation and with two types of instructions. This experiment contributed to show that immediate memory for sentences can be affected by appropriate instructions, and that after a short time after presentation only the main semantic information of the sentences is recalled. An alternative model is presented, based on the notion of storage of the meaningful elements of the sentences in a rather abstract form, and of recall as a reconstructive process to produce new sentences. The results of two new experiments on sentence memory, the first a free and prompted recall experiment with children, the second a recognition memory study with adolescents, are then presented and discussed in relation to the model.     

Modulation of working memory updating: Does long-term memory lexical association matter?

The aim of the present study was to investigate how working memory updating for verbal material is modulated by enduring properties of long-term memory. Two coexisting perspectives that account for the relation between long-term representation and short-term performance were addressed. First, evidence suggests that performance is more closely linked to lexical properties, that is, co-occurrences within the language. Conversely, other evidence suggests that performance is linked more to long-term representations which do not entail lexical/linguistic representations. Our aim was to investigate how these two kinds of long-term memory associations (i.e., lexical or nonlexical) modulate ongoing working memory activity. Therefore, we manipulated (between participants) the strength of the association in letters based on either frequency of co-occurrences (lexical) or contiguity along the sequence of the alphabet (nonlexical). Results showed a cost in working memory updating for strongly lexically associated stimuli only. Our findings advance knowledge of how lexical long-term memory associations between consonants affect working memory updating and, in turn, contribute to the study of factors which impact the updating process across memory systems.     

Immediate memory for faces: Long- or short-term memory?

Immediate recognition memory span and short-term forgetting for non-verbal stimuli (“unfamiliar faces”) were investigated in normal subjects and amnesic patients. Surnames were used as a verbal control. It was found that normal subjects had a reliable immediate recognition span of one for faces and that there was no decrement in performance in the retention of three faces over a 30-s interval. Amnesic subjects were impaired on both the immediate memory span task and on the short-term forgetting task. This pattern of results contrasts with those obtained using surnames on which the results were comparable to other verbal S.T.M. tasks. It is suggested that performance on these tasks of recognition memory for faces is determined by L.T.M. processes. The implications for the interpretation of S.T.M. are discussed.     

The substrate for long-lasting memory: If not protein synthesis,then what?

The prevailing textbook view that de novo protein synthesis is required for memory (e.g., [Bear, M. F., Connors, B., & Paradiso, M. 2006. Neuroscience. Lippincott, New York]) is seriously flawed and an alternative hypothesis has been proposed in which post-translational modification (PTM) of proteins already synthesized and already present within the synapse is 'the' substrate for long-lasting memory. Protein synthesis serves a replenishment role. The first part of this review discusses how long-lasting memory can be achieved with 'only' PTM of existing synaptic proteins. The second part critically reviews a recent report published in Neuron 2007 that exemplifies the current view of protein synthesis and memory while also illustrating how these results can be understood within this new PTM framework. A necessary yet unexpected conclusion to emerge from consideration of the consequences of a PTM mechanism as the necessary, sufficient and exclusive substrate for long-lasting memory, is that the central Hebbian dogma that cells that 'fire together, wire together' is an unlikely mechanism for long-lasting memory. Thus, a unique feature of the PTM model is that longevity of information storage is achieved not by stability of the synaptic mechanism, but by impermanent pseudoredundant circuits. This is so because PTM is a reversible process and thus any permanent connection, any 'lasting effect' cannot be in the form of stable synapse formation. We have therefore proposed a solution in which network level processes regulate cellular mechanisms, even as such mechanisms regulate the network. Thus, synapses are 'meta-stabilized' by regulated feedback mediated by the circuit in which the synapse is embedded. For example, spontaneous activity is proposed to be a substrate feedback mechanism we term 'cryptic rehearsal' to sustain for some period of time after learning an approximation to the state initially created by input. Additionally, because the duplication of these traces is ongoing, this provides a degenerate code for the engram. Stability is thus achieved, not by stabilizing the synapse, but by implementing a pseudo-redundant yet malleable circuitry so that memory can be protected in the face of small catastrophes in network representation.     

How many pixels make a memory? Picture memory for small pictures

Torralba (Visual Neuroscience, 26, 123–131, 2009) showed that, if the resolution of images of scenes were reduced to the information present in very small “thumbnail images,” those scenes could still be recognized. The objects in those degraded scenes could be identified, even though it would be impossible to identify them if they were removed from the scene context. Can tiny and/or degraded scenes be remembered, or are they like brief presentations, identified but not remembered. We report that memory for tiny and degraded scenes parallels the recognizability of those scenes. You can remember a scene to approximately the degree to which you can classify it. Interestingly, there is a striking asymmetry in memory when scenes are not the same size on their initial appearance and subsequent test. Memory for a large, full-resolution stimulus can be tested with a small, degraded stimulus. However, memory for a small stimulus is not retrieved when it is tested with a large stimulus.     

Recognition of music in long-term memory: Are melodic and temporal patterns equal partners?

The notion that the melody (i.e., pitch structure) of familiar music is more recognizable than its accompanying rhythm (i.e., temporal structure) was examined with the same set of nameable musical excerpts in three experiments. In Experiment 1, the excerpts were modified so as to keep either their original pitch variations, whereas durations were set to isochrony (melodic condition) or their original temporal pattern while played on a single constant pitch (rhythmic condition). The subjects, who were selected without regard to musical training, were found to name more tunes and to rate their feeling of knowing the musical excerpts far higher in the melodic condition than in the rhythmic condition. These results were replicated in Experiment 2, wherein the melodic and rhythmic patterns of the musical excerpts were interchanged to create chimeric mismatched tunes. The difference in saliency of the melodic pattern and the rhythmic pattern also emerged with a music-title-verification task in Experiment 3, hence discarding response selection as the main source of the discrepancy. The lesser effectiveness of rhythmic structure appears to be related to its lesser encoding distinctiveness relative to melodic structure. In general, rhythm was found to be a poor cue for the musical representations that are stored in long-term memory. Nevertheless, in all three experiments, the most effective cue for music identification involved the proper combination of pitches and durations. Therefore, the optimal code of access to long-term memory for music resides in a combination of rhythm and melody, of which the latter would be the most informative.     

Do serotonin1–7 receptors modulate short and long-term memory?

Evidence from invertebrates to human studies indicates that serotonin (5-hydroxytryptamine; 5-HT) system modulates short- (STM) and long-term memory (LTM). This work is primarily focused on analyzing the contribution of 5-HT, cholinergic and glutamatergic receptors as well as protein synthesis to STM and LTM of an autoshaping learning task. It was observed that the inhibition of hippocampal protein synthesis or new mRNA did not produce a significant effect on autoshaping STM performance but it did impair LTM. Both non-contingent protein inhibition and 5-HT depletion showed no effects. It was basically the non-selective 5-HT receptor antagonist cyproheptadine, which facilitated STM. However, the blockade of glutamatergic and cholinergic transmission impaired STM. In contrast, the selective 5-HT(1B) receptor antagonist SB-224289 facilitated both STM and LTM. Selective receptor antagonists for the 5-HT(1A) (WAY100635), 5-HT(1D) (GR127935), 5-HT(2A) (MDL100907), 5-HT(2C/2B) (SB-200646), 5-HT(3) (ondansetron) or 5-HT(4) (GR125487), 5-HT(6) (Ro 04-6790, SB-399885 and SB-35713) or 5-HT(7) (SB-269970) did not impact STM. Nevertheless, WAY100635, MDL100907, SB-200646, GR125487, Ro 04-6790, SB-399885 or SB-357134 facilitated LTM. Notably, some of these changes shown to be independent of food-intake. Concomitantly, these data indicate that '5-HT tone via 5-HT(1B) receptors' might function in a serial manner from STM to LTM, whereas working in parallel using 5-HT(1A), 5-HT(2A), 5-HT(2B/2C), 5-HT(4), or 5-HT(6) receptors.     

Is knowledge base development a necessary and sufficient condition for memory development?

The hypothesis that knowledge base development is an important condition for memory development was tested in two experiments. In Experiment 1 subjects from grades K, 6, and college participated in an incidental learning task where they analyzed words according to one of four featural systems: physical, acoustic, semantic, and imagery. Large developmental differences in recall were found in the imagery and semantic conditions, small differences were observed in the acoustic conditions, and no developmental differences were found in the physical condition. Experiment 2 involved presenting college students and third graders words either from categories highly salient to third graders, e.g., cartoons, games, etc., or from corresponding Battig and Montague categories generated by college students. Free recall and clustering performances showed significant interactions, with third graders superior on the third-grade salient items, and college students superior on Battig and Montague items.     

Full-time studying and long-term relationships: Make or break for mature students?

Results are reported of a 2-year longitudinal study looking at the effects of full-time degree study on full-time mature students who were also in long-term committed relationships. The findings from the first year of the research suggested that while there were particular stresses for students with domestic responsibilities; the single most buffering effect was support from the student's partner. The follow-up study in the second year confirmed these findings, but also suggested that there was a decrease in the amount of partner support experienced in the second year. The implications for counselling and student support services are discussed.     

What's in a name for memory errors? Implications and ethical issues arising from the use of the term "false memory" for errors in memory for details

The term "false memories" has been used to refer to suggestibility experiments in which whole events are apparently confabulated and in media accounts of contested memories of childhood abuse. Since 1992 psychologists have increasingly used the term "false memory" when discussing memory errors for details, such as specific words within lists. Use of the term to refer to errors in details is a shift in language away from other terms used historically (e.g., "memory intrusions"). We empirically examine this shift in language and discuss implications of the new use of the term "false memories." Use of the term presents serious ethical challenges to the data-interpretation process by encouraging over-generalization and misapplication of research findings on word memory to social issues.     

Septohippocampal acetylcholine: involved in but not necessary for learning and memory?

The neurotransmitter acetylcholine (ACh) has been accorded an important role in supporting learning and memory processes in the hippocampus. Cholinergic activity in the hippocampus is correlated with memory, and restoration of ACh in the hippocampus after disruption of the septohippocampal pathway is sufficient to rescue memory. However, selective ablation of cholinergic septohippocampal projections is largely without effect on hippocampal-dependent learning and memory processes. We consider the evidence underlying each of these statements, and the contradictions they pose for understanding the functional role of hippocampal ACh in memory. We suggest that although hippocampal ACh is involved in memory in the intact brain, it is not necessary for many aspects of hippocampal memory function.     

Three-year-olds’ memory for a person met only once at the age of 12 months: Very long-term memory revealed by a late-manifesting novelty preference

This study examined three-year-olds’ verbal and non-verbal memory for a person met only once after a 28 month interval. Children in the Test group (N = 50) had participated in an earlier experiment at our lab at the age of 12 months where they met one of two possible experimenters. At this past event half of the children were tested by one, the other half by the other experimenter. At the follow-up, run by a naïve experimenter, the children were shown two videos from the original experiment in a visual paired comparison task: One with the specific experimenter testing them at the original visit (the Target) and one of the other experimenter (the Foil), with whom they had no experience. When explicitly asked, the children’s responses did not differ from chance. However, eye-tracking data revealed a late-manifesting novelty preference for the “Foil” person indicating memory for the “Target” person met once before.     

Prospective memory: Are preparatory attentional processes necessary for a single focal cue?

The preparatory attentional and memory processes theory of prospective memory (PM) assumes that PM retrieval requires resource-demanding preparatory attentional processes, whereas the multiprocess theory assumes that retrieval can also occur spontaneously. On the basis of showing slowing on an ongoing task (i.e., task interference) —even when the PM cue was highly salient (i.e., the participant’s own name) —Smith, Hunt, McVay, and McConnell (2007) concluded that preparatory attentional processes are always necessary for PM retrieval. We argue that the presence of preparatory attentional processes cannot be used to rule out the existence of spontaneous retrieval processes, and the goal of the present research was to examine whether PM retrieval can occur in the absence of preparatory attentional processes. We varied whether we emphasized the importance of the PM task or the ongoing task, and we assessed task interference across quarters of the ongoing task. Our results showed no evidence of task interference and, hence, no evidence of preparatory attentional processes in the periods proximal to the target event, and yet participants showed high PM performance. Thus, the results suggest the existence of spontaneous retrieval processes and support the multiprocess theory.     

Is external memory memory? Biological memory and extended mind

Clark and Chalmers (1998) claim that an external resource satisfying the following criteria counts as a memory: (1) the agent has constant access to the resource; (2) the information in the resource is directly available; (3) retrieved information is automatically endorsed; (4) information is stored as a consequence of past endorsement. Research on forgetting and metamemory shows that most of these criteria are not satisfied by biological memory, so they are inadequate. More psychologically realistic criteria generate a similar classification of standard putative external memories, but the criteria still do not capture the function of memory. An adequate account of memory function, compatible with its evolution and its roles in prospection and imagination, suggests that external memory performs a function not performed by biological memory systems. External memory is thus not memory. This has implications for: extended mind theorizing, ecological validity of memory research, the causal theory of memory.