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People often subdivide a list into smaller pieces, called chunks. Some theories of serial recall assume memories are stored hierarchically, with all-or-none retrieval of chunks, but most mathematical models avoid hierarchical assumptions. Johnson (Journal of Verbal Learning and Verbal Behavior, 8(6), 725–731, 1969) found steep drops in errors following correct recalls (transitional-error probabilities) within putative chunks during multi-trial letter-list learning, and viewed this as evidence for all-or-none retrieval. Here we test whether all-or-none retrieval occurs in lists studied only once. In serial recall of six-word lists (Experiment 1), transitional-error probabilities were inconsistent with all-or-none retrieval, both when participants were instructed to subdivide and when temporal grouping induced subdivision. Curiously, the same analysis of previous temporally grouped nine-letter lists produced compelling evidence for all-or-none retrieval, which may result from recoding rather than the formation of chunks. In Experiment 2, participants were pre-trained on three-word chunks. For nine-word lists constructed from those trained chunks, transitional-error probabilities exhibited more pronounced evidence of all-or-none retrieval. Nearly all effects reversed with post-cued backward recall, suggesting mechanisms that play out over the course of recall rather than encoding of the list. In sum, subdivided lists do not result in hierarchical memories after a single study trial, although they may emerge in lists formed from chunks that are previously learned as such. This suggests a continuous transition from non-hierarchical subdivision of lists to all-or-none retrieval over the course of chunk formation. [ABSTRACT FROM AUTHOR]

Interactive imagery, one of the most effective strategies for remembering pairs of words, involves asking participants to form mental images during study. We tested the hypothesis that the visual image is, in fact, responsible for its memory benefit. Neither subjectively reported vividness (all experiments) nor objective imagery skill (experiments 1 and 3) could explain the benefit of interactive imagery for cued recall. Aphantasic participants, who self-identified little to no mental imagery, benefited from interactive-imagery instructions as much as controls (experiment 3). Imagery instructions did not improve memory for the constituent order of associations (AB versus BA), even when participants were told how to incorporate order within their images (experiments 1 and 2). Taken together, our results suggest that the visual format of images may not be responsible for the effectiveness of the interactive-imagery instruction and moreover, interactive imagery may not result in qualitatively different associative memories. [ABSTRACT FROM AUTHOR]

When lists are presented with temporal pauses between groups of items, participants' response times reiterate those pauses. Accuracy is also increased, especially at particular serial positions. By comparing forward with backward serial recall, we tested whether the influence of temporal grouping is primarily a function of serial position or output position. Results favored the latter, both when recall direction was known to participants prior to (Experiment 2) or only after (Experiment 2) studying each list. Alongside fits of variants of a temporal distinctiveness-based model, our findings suggest that the influence of temporal grouping is not just a consequence of grouping information stored during the study phase. Rather, it critically depends on participants cueing with within-chunk position during recall, combined with response suppression. [ABSTRACT FROM AUTHOR]

Attributes of words, such as frequency and imageability, can influence memory for order. In serial recall, Hulme, Stuart, Brown, and Morin ( Journal of Memory and Language, 49(4), 500-518, 2003) found that high-frequency words were recalled worse, and low-frequency words better, when embedded in alternating lists than pure lists. This is predicted by associative chaining, wherein each recalled list-item becomes a recall-cue for the next item. However, Hulme, Stuart, Brown, and Morin ( Journal of Memory and Language, 49(4), 500-518, 2003) argued their findings supported positional-coding models, wherein items are linked to a representation of position, with no direct associations between items. They suggested their serial-position effects were due to pre-experimental semantic similarity between pairs of items, which depended on frequency, or a complex tradeoff between item- and order-coding (Morin, Poirier, Fortin, & Hulme, Psychonomic Bulletin Review, 13(4), 724-729, 2006). We replicated the smooth serial-position effects, but accounts based on pre-existing similarity or item-order tradeoffs were untenable. Alternative accounts based, on imageability, phonological and lexical neighbourhood sizes were also ruled out. The standard chaining account predicts that if accuracy is conditionalized on whether the prior item was correct, the word-frequency effect should reappear in alternating lists; however, this prediction was not borne out, challenging this retrieval-based chaining account. We describe a new account, whereby frequency influences the strengths of item-item associations, symmetrically, during study. A manipulation of word-imageability also produced a pattern consistent with item-item cueing at study, but left room for effects of imageability at the final stage of recall. These findings provide further support for the contribution of associative chaining to serial-recall behaviour and show that item-properties may influence serial-recall in multiple ways. [ABSTRACT FROM AUTHOR]

Understanding memory function amounts to identifying how events (cognitive and neural) at study eventually influence events at test. Many of the proposed cognitive correlates of memory-related event-related potentials (ERPs) at study resemble proposed cognitive correlates of other memory-related ERPs, recorded at test. We wondered whether a given known ERP feature at study might in fact reflect an effective-encoding process that is, in turn, tapped by another specific ERP feature, recorded at test. To this end, we asked which pairs of known memory-related ERP features explain common variance across a large sample of participants, while they perform a word-recognition task. Two early ERP features, the Late Positive Component (study) and the FN400 (test), covaried significantly. These features also correlated with memory success (d′ and response time). Two later ERP features, the Slow Wave (study) and the Late Parietal Positivity (test), also covaried when lures were incorporated into the analysis. Interestingly, these later features were uncorrelated with memory outcome. This novel approach, exploiting naturally occurring subject variability (in strategy and ERP amplitudes), informs our understanding of the memory functions of ERP features in several ways. Specifically, they strengthen the argument that the earlier ERP features may drive old/new recognition (but perhaps not the later features). Our findings suggest the Late Positive Component at study, in some degree, may cause the FN400 to increase at test, together producing effective recognition memory. The Slow Wave at study appears to relate the Left Parietal Positivity at test, but these may play roles in more complex memory judgments and may be less critical for simple old/new recognition. [ABSTRACT FROM AUTHOR]

The judgement of relative order (JOR) procedure is used to investigate serial-order memory. Measuring response times, the wording of the instructions (whether the earlier or the later item was designated as the target) reversed the direction of search in subspan lists (Chan, Ross, Earle, & Caplan Psychonomic Bulletin & Review, 16(5), 945-951, ). If a similar congruity effect applied to above-span lists and, furthermore, with error rate as the measure, this could suggest how to model order memory across scales. Participants performed JORs on lists of nouns (Experiment 1: list lengths = 4, 6, 8, 10) or consonants (Experiment 2: list lengths = 4, 8). In addition to the usual distance, primacy, and recency effects, instructions interacted with serial position of the later probe in both experiments, not only in response time, but also in error rate, suggesting that availability, not just accessibility, is affected by instructions. The congruity effect challenges current memory models. We fitted Hacker's ( Journal of Experimental Psychology: Human Learning and Memory, 6(6), 651-675, ) self-terminating search model to our data and found that a switch in search direction could explain the congruity effect for short lists, but not longer lists. This suggests that JORs may need to be understood via direct-access models, adapted to produce a congruity effect, or a mix of mechanisms. [ABSTRACT FROM AUTHOR]

Delayed action research has suggested that perceptual information about a visual stimulus decays over several seconds. With event-related potential (ERP) methodology, one should be able to track the time course of the electrophysiological processes associated with this decay. Recently, Cruikshank et al. (J Vis 12:29, ) found that the N170 ERP component reflected ventral stream processes linked to motor planning and perception for action. Specifically, the N170 was larger for actions that relied on perceptual-based information. However, the delay interval was very short (tens of ms). Behavioral and neuroimaging studies suggest that when longer delays are employed, reactivation of ventral areas is necessary in order to access a stored representation of the target's characteristics. Therefore, the N170 may reflect not only the perception-for-action processes, but also the accuracy of the representation. In order to test this, we traced the time course of the N170 in memory-guided reaching when 1-, 2-, and 3-s delays separated target occlusion and response initiation. During reach initiation, the N170 was more negative and peaked earlier for the 1 s than the 2- and 3-s delays and correlated significantly with performance at the longest delay. These results suggest that the neural mechanisms involved in movement planning change for delays beyond 1 s. The smaller N170 may reflect an impoverished visual perceptual representation in the ventral stream. To our knowledge, these are the first electrophysiological results to suggest that there is decay of visual perceptual information that occurs with increasing time. [ABSTRACT FROM AUTHOR]

Memory often requires knowledge of the order of events. Previous findings about immediate judgments of relative order in short, subspan lists are variable regarding whether participants' strategy is to search memory in the forward direction, starting from the first list item and progressing toward the end item, or in the backward direction, starting from the end item and progressing toward the start. We asked whether wording of the instructions influences participants' search direction. Participants studied sequences of three to six consonants, and for an immediate, two-item probe of each list, judged which probe was presented earlier ('earlier' instruction) or later ('later' instruction) on the list. Forward and backward searches were supported for 'earlier' and 'later' instructions, respectively. Our findings suggest that participants have more than one effective strategy for order judgments in short lists, and that subtle instructional differences can bias memory search in either the forward or backward direction. [ABSTRACT FROM AUTHOR]

Place cells of the rodent hippocampus constitute one of the most striking examples of a correlation between neuronal activity and complex behaviour in mammals. These cells increase their firing rates when the animal traverses specific regions of its surroundings, providing a context-dependent map of the environment. Neuroimaging studies implicate the hippocampus and the parahippocampal region in human navigation. However, these regions also respond selectively to visual stimuli. It thus remains unclear whether rodent place coding has a homologue in humans or whether human navigation is driven by a different, visually based neural mechanism. We directly recorded from 317 neurons in the human medial temporal and frontal lobes while subjects explored and navigated a virtual town. Here we present evidence for a neural code of human spatial navigation based on cells that respond at specific spatial locations and cells that respond to views of landmarks. The former are present primarily in the hippocampus, and the latter in the parahippocampal region. Cells throughout the frontal and temporal lobes responded to the subjects' navigational goals and to conjunctions of place, goal and view. [ABSTRACT FROM AUTHOR]

For palm of meaningful items (e.g., words), recall accuracy is nearly identical for forward and backward probes. That is, after studying an A-B pair, subjects can recall A given B as well as they can recall B given A (Kahana, 2002). To assess whether this symmetry property is unique to pairs, we investigated the effects of study direction on probed recall of word triples and serial lists. Two experiments revealed a forward-recall advantage in both triples and serial lists. In addition, compound cues produced better recall than did single-item adjacent cues, which, in turn, produced better recall than did remote cues. These findings suggest a discontinuity between the associative processes supporting memory for pairs and those supporting memory for sequences of three or more items. [ABSTRACT FROM AUTHOR]

Presents research which examined theta oscillations in subdural recordings from epileptic patients learning to navigate computer-generated mazes. Theta oscillations in spatial navigation in rodents; Details about the raw intracranial signal and spectral analysis; Factors upon which theta activity is dependent; Frequency of the oscillations.