Three more semantic serial position functions and a SIMPLE explanation

There are innumerable demonstrations of serial position functions—with characteristic primacy and recency effects—in episodic tasks, but there are only a handful of such demonstrations in semantic memory tasks, and those demonstrations have used only two types of stimuli. Here, we provide three more examples of serial position functions when recalling from semantic memory. Participants were asked to reconstruct the order of (1) two cartoon theme song lyrics, (2) the seven Harry Potter books, and (3) two sets of movies, and all three demonstrations yielded conventional-looking serial position functions with primacy and recency effects. The data were well-fit by SIMPLE, a local distinctiveness model of memory that was originally designed to account for serial position effects in short- and long-term episodic memory. According to SIMPLE, serial position functions in both episodic and semantic memory tasks arise from the same type of processing: Items that are more separated from their close neighbors in psychological space at the time of recall will be better remembered. We argue that currently available evidence suggests that serial position functions observed when recalling items that are presumably in semantic memory arise because of the same processes as those observed when recalling items that are presumably in episodic memory.     

Testing the associative-link hypothesis in immediate serial recall: Evidence from word frequency and word imageability effects

Two immediate serial recall experiments were conducted to test the associative-link hypothesis (Stuart & Hulme, 2000 Stuart, G. and Hulme, C. 2000. The effects of word co-occurrence on short-term memory: Associative-links in long-term memory affect short-term memory performance. Journal of Experimental Psychology: Learning, Memory, and Cognition, 26: 796–802. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). We manipulated interitem association by varying the intralist latent semantic analysis (LSA) cosines in our 7-item study word lists, each of which consists of high- or low-frequency words in Experiment 1 and high- or low-imageability words in Experiment 2. Whether item recall performance was scored by a serial-recall or free-recall criterion, we found main effects of interitem association, word imageability, and word frequency. The effect of interitem association also interacted with the word frequency effect, but not with the word imageability effect. The LSA-cosine×word frequency interaction occurred in the recency, but not primacy, portion of the serial position curve. The present findings set explanatory boundaries for the associative-link hypothesis and we argue that both item- and associative-based mechanisms are necessary to account for the word frequency effect in immediate serial recall.     

Primacy and recency in nonword repetition

An increasing body of evidence suggests that nonword repetition is related to immediate serial memory (e.g., ; ). One possible account of this relationship is that a nonword is processed like a list when it is first encountered. If this is the case, it should be possible to detect serial position effects in repetition of single nonwords. Three experiments tested this prediction. Experiment 1 examined whether there would be syllable serial position primacy and recency effects in repetition of polysyllabic nonwords, and obtained both primacy and recency effects. Experiments 2 and 3 showed that these effects were not due to the controlled duration of the nonwords or the requirements of concurrent articulation or the procedure by which nonwords were created.     

Serial position effects in 2-alternative forced choice recognition: Functional equivalence across visual and auditory modalities

Two experiments examined Ward, Avons, and Melling's (2005) proposition that the serial position function is task, rather than modality, dependent. Specifically, they proposed that for backward testing the 2-alternative forced-choice (2AFC) recognition paradigm is characterised by single-item recency irrespective of the modality of the stimulus presentation. In Experiment 1 the same nonword sequences, presented both visually or auditorily, produced qualitatively equivalent serial position functions with 2AFC testing. Forward testing produced a flat serial position function, while backward testing produced two-item recency in the absence of primacy. In order to rule out the possibility that the serial position functions for visual stimuli were the product of sub-vocal rehearsal, Experiment 2 employed articulatory suppression during the presentation phase. Serial position function equivalence was again observed together with a modest impairment in overall recognition rates. Taken together, these data are consistent with the Ward et al. proposition and further support the existence of a visual memory that can facilitate storage of visual-verbal material (e.g. Logie, Della Sella, Wynn, & Baddeley, 2000). However, the observation of two-item recency contradicts the original duplex account of single-item recency traditionally observed for backwards recognition testing of visual stimuli (Phillips & Christie, 1977).     

Primacy and recency in nonword repetition

An increasing body of evidence suggests that nonword repetition is related to immediate serial memory (e.g., Baddeley, Gathercole, & Papagno, 1998; Gathercole & Baddeley, 1993). One possible account of this relationship is that a nonword is processed like a list when it is first encountered. If this is the case, it should be possible to detect serial position effects in repetition of single nonwords. Three experiments tested this prediction. Experiment 1 examined whether there would be syllable serial position primacy and recency effects in repetition of polysyllabic nonwords, and obtained both primacy and recency effects. Experiments 2 and 3 showed that these effects were not due to the controlled duration of the nonwords or the requirements of concurrent articulation or the procedure by which nonwords were created.     

Serial position memory in the visual—spatial domain: Reconstructing sequences of unfamiliar faces

In two studies we presented pictures of unfamiliar faces one at a time, then presented the complete set at test and asked for serial reconstruction of the order of presentation. Serial position functions were similar to those found with verbal materials, with considerable primacy and one item recency, position errors that were mainly to the adjacent serial position, a visual similarity effect, and effects of articulatory suppression that did not interact with the serial position effect or with the similarity effect. Serial position effects were found when faces had been seen for as little as 300 ms and after a 6-s retention interval filled with articulatory suppression. Serial position effects found with unfamiliar faces are not based on verbal encoding strategies, and important elements of serial memory may be general across modalities.     

Serial position effects in implicit memory

Serial position effects in explicit and implicit memory were investigated in a noncolour word Stroop task. Participants were presented with a study list of four words printed in different colours and were tested for memory of the list position of the colour (explicit memory task); they were then asked to complete a word stem primed (or not primed) by one of the words in the study list (implicit memory task), a task presented as a distractor task. Serial position effects were observed in both explicit and implicit memory, for both response times and proportion of correct responses, with marked primacy effects, a drop in performance towards the third list position and a rise in memory performance at the fourth list position, the recency effect being most pronounced in implicit memory. It is concluded that explicit and implicit expressions of memory are governed by similar principles of temporal information processing.     

Serial position effects in implicit memory for multiple-digit numbers

Serial position effects in implicit and explicit memory were investigated in a short-term memory task. A study list composed of four, spatially distributed, two-digit numbers was presented, followed by an item recognition task (explicit test) and an implicit memory task in which participants were asked to verify a simple addition equation where the presented answer was either primed or not primed by one of the number pairs in the study list. Similar serial position effects were observed in explicit and implicit memory, with faster response times for correct decisions on the first than on the later list positions. The presence of a primacy effect but no recency effect is consistent with previous studies of explicit memory with visual presentation. The results suggest that similar principles of temporal information processing govern priming and episodic short-term memory.     

Serial position effects in semantic memory: reconstructing the order of verses of hymns

Serial position effects (primacy and recency) have been consistently demonstrated in both short- and long-term episodic memory tasks. The search for corresponding effects in semantic memory tasks (e.g., reconstructing the order of U.S. presidents) has been confounded by factors such as differential exposure to stimuli. In the present study, the stimuli were six-verse hymns that would have been sung from the first to the last verse by churchgoers on numerous occasions. Participants were presented with the verses of each hymn in random order and were required to reconstruct the correct order. Primacy and recency effects were significantly more evident for churchgoers than for nonchurchgoers. Moreover, error gradients were steeper than chance for churchgoers but not for nonchurchgoers; in other words, churchgoers' errors were more likely to be close to the correct position than further away. These findings provide the first unequivocal demonstration of serial position effects in semantic memory.     

Serial position functions for recognition of olfactory stimuli

Two experiments examined item recognition memory for sequentially presented odours. Following a sequence of six odours participants were immediately presented with a series of two-alternative forced-choice (2AFC) test odours. The test pairs were presented in either the same order as learning or the reverse order of learning. Method of testing was either blocked (Experiment 1) or mixed (Experiment 2). Both experiments demonstrated extended recency, with an absence of primacy, for the reverse testing procedure. In contrast, the forward testing procedure revealed a null effect of serial position. The finding of extended recency is inconsistent with the single-item recency predicted by the two-component duplex theory (Phillips & Christie, 1977 Phillips, W. A. and Christie, D. F. M. 1977. Components of visual memory. Quarterly Journal of Experimental Psychology, 29: 117–133. [Taylor & Francis Online], [Web of Science ®] , [Google Scholar]). We offer an alternative account of the data in which recognition accuracy is better accommodated by the cumulative number of items presented between item learning and item test.     

Further differentiating item and order information in semantic memory: students’ recall of words from the “CU Fight Song”, Harry Potter book titles,and Scooby Doo theme song

University of Colorado (CU) students were tested for both order and item information in their semantic memory for the “CU Fight Song”. Following an earlier study by Overstreet and Healy [(2011). Item and order information in semantic memory: Students’ retention of the “CU fight song” lyrics. Memory & Cognition, 39, 251–259. doi:10.3758/s13421-010-0018-3], a symmetrical bow-shaped serial position function (with both primacy and recency advantages) was found for reconstructing the order of the nine lines in the song, whereas a function with no primacy advantage was found for recalling a missing word from each line. This difference between order and item information was found even though students filled in missing words without any alternatives provided and missing words came from the beginning, middle, or end of each line. Similar results were found for CU students’ recall of the sequence of Harry Potter book titles and the lyrics of the Scooby Doo theme song. These findings strengthen the claim that the pronounced serial position function in semantic memory occurs largely because of the retention of order, rather than item, information.     

Tactile Ranschburg effects: facilitation and inhibitory repetition effects analogous to verbal memory

The present paper examines the effect of within-sequence item repetitions in tactile order memory. Employing an immediate serial recall procedure, participants reconstructed a six-item sequence tapped upon their fingers by moving those fingers in the order of original stimulation. In Experiment 1a, within-sequence repetition of an item separated by two-intervening items resulted in a significant reduction in recall accuracy for that repeated item (i.e., the Ranschburg effect). In Experiment 1b, within-sequence repetition of an adjacent item resulted in significant recall facilitation for that repeated item. These effects mirror those reported for verbal stimuli (e.g., Henson, 1998a Henson, R. N. A. (1998a). Item repetition in short-term memory: Ranschburg repeated. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24(5), 1162–1181. doi:doi.org/10.1037/0278-7393.24.5.1162[Crossref], [PubMed], [Web of Science ®] , [Google Scholar]. Item repetition in short-term memory: Ranschburg repeated. Journal of Experimental Psychology: Learning, Memory, and Cognition, 24(5), 1162–1181. doi:doi.org/10.1037/0278-7393.24.5.1162). These data are the first to demonstrate the Ranschburg effect with non-verbal stimuli and suggest further cross-modal similarities in order memory.     

Immediate recognition memory for wine

We describe a preliminary investigation concerning the short-term recognition memory function for gustatory stimuli (wines). In Experiment 1A, 24 non-expert wine drinkers completed a yes/no recognition task for 3-wine sequences. For the raw recognition scores, the serial position function comprised both primacy and recency. Recency did not, however, achieve significance for the d′ scores. In Experiment 1B, 24 participants completed the same yes/no recognition task for 3-visual matrix sequences. In contrast to Experiment 1A, the serial position function comprised recency and an absence of primacy. We argue that the presence of primacy for the wine sequences cannot be interpreted via a verbal labelling strategy, nor can it be interpreted via proactive interference from the first wine in the list on subsequent list items. The result suggests qualitative differences in the memory processing for gustatory and non-verbal visual stimuli.     

Inter- and intra-individual variation in immediate free recall: an examination of serial position functions and recall initiation strategies

Serial position functions in immediate free recall have been historically noted for their bowed shape, where items presented at the beginning (primacy) and end (recency) of a list are better remembered than those presented in the middle. While extensive work has examined these effects, researchers typically ignore the systematic differences among individuals that likely contribute, but are lost when using an aggregate function. In the current study, inter- and intra-individual differences in serial position functions and differences in recall strategies were examined. Participants performed a free recall task on multiple lists. Three groups of participants were derived based on the relative profiles in their serial position functions. These groups differed in the extent that they output mainly primacy items, recency items, or both primacy and recency items. Performance on immediate free recall and on cognitive ability tasks was compared between these three groups. Systematic inter- and intra-individual variation in recall strategies led to differential profiles of performance in immediate free recall, which was also related to the additional cognitive ability measures. Performance on a task can be due to the utilisation of a variety of control processes that emphasise various components of that task over other components.     

A comparison of serial position effects in implicit and explicit word-stem completion

In this study I examined a further possible dissociation between implicit and explicit memory—whether implicit memory produces serial position effects that are similar to those found in explicit memory. When implicit word-stem completion and explicit word-stem cued recall were compared, only the explicit test showed significant primacy and recency effects. The explicit test was sensitive to the order in which stimuli words were encoded, but the implicit test was not. This dissociation between implicit and explicit memory provides further evidence that conscious retrieval processes were not involved in the implicit test.     

Auditory and visual serial position functions obey different laws

Rhesus monkeys were tested in serial probe recognition tasks with either travel slide pictures or natural sounds. Tests with four-item lists produced serial position functions that were essentially opposite in shape for the two modalities and changed in opposite ways with retention interval. For visual memory, the primacy effect grew and the recency effect dissipated with retention interval. Capuchin monkeys, humans, and pigeons showed similar results. For auditory memory with rhesus monkeys, the recency effect grew and the primacy effect dissipated with retention interval. These results taken together, along with results from rehearsal tests of monkeys and humans, implicate two passive memory processes with different time courses. Interference among items within auditory lists was manipulated by varying the time between items and categories of items. Interference across lists was manipulated by varying the item pool size and, hence, item repetitions. Changes in the auditory serial position functions indicated that proactive and retroactive interference may have been instrumental in these dynamically changing serial position functions. Implications for theories and models of memory are discussed.     

Sequential dynamics in visual short-term memory

Visual short-term memory (VSTM) is thought to help bridge across changes in visual input, and yet many studies of VSTM employ static displays. Here we investigate how VSTM copes with sequential input. In particular, we characterize the temporal dynamics of several different components of VSTM performance, including: storage probability, precision, variability in precision, guessing, and swapping. We used a variant of the continuous-report VSTM task developed for static displays, quantifying the contribution of each component with statistical likelihood estimation, as a function of serial position and set size. In Experiments 1 and 2, storage probability did not vary by serial position for small set sizes, but showed a small primacy effect and a robust recency effect for larger set sizes; precision did not vary by serial position or set size. In Experiment 3, the recency effect was shown to reflect an increased likelihood of swapping out items from earlier serial positions and swapping in later items, rather than an increased rate of guessing for earlier items. Indeed, a model that incorporated responding to non-targets provided a better fit to these data than alternative models that did not allow for swapping or that tried to account for variable precision. These findings suggest that VSTM is updated in a first-in-first-out manner, and they bring VSTM research into closer alignment with classical working memory research that focuses on sequential behavior and interference effects.     

Serial position effects in recognition memory for odors: A reexamination

Seven experiments examined recognition memory for sequentially presented odors. Following Reed (2000), participants were presented with a sequence of odors and then required to identify an odor from the sequence in a test probe comprising 2 odors. The pattern of results obtained by Reed (2000, although statistically marginal) demonstrated enhanced recognition for odors presented at the start (primacy) and end (recency) of the sequence: a result that we failed to replicate in any of the experiments reported here. Experiments 1 and 3 were designed to replicate Reed (2000), employing five-item and seven-item sequences, respectively, and each demonstrated significant recency, with evidence of primacy in Experiment 3 only. Experiment 2 replicated Experiment 1, with reduced interstimulus intervals, and produced a null effect of serial position. The ease with which the odors could be verbally labeled was manipulated in Experiments 4 and 5. Nameable odors produced a null effect of serial position (Experiment 4), and hard-to-name odors produced a pronounced recency effect (Experiment 5); nevertheless, overall rates of recognition were remarkably similar for the two experiments at around 70%. Articulatory suppression reduced recognition accuracy (Experiment 6), but recency was again present in the absence of primacy. Odor recognition performance was immune to the effects of an interleaved odor (Experiment 7), and, again, both primacy and recency effects were absent. There was no evidence of olfactory fatigue: Recognition accuracy improved across trials (Experiment 1). It is argued that the results of the experiments reported here are generally consistent with that body of work employing hard-to-name visual stimuli, where recency is obtained in the absence of primacy when the retention interval is short.     

A recency-based account of the primacy effect in free recall

Seven experiments investigated the role of rehearsal in free recall to determine whether accounts of recency effects based on the ratio rule could be extended to provide an account of primacy effects based on the number, distribution, and recency of the rehearsals of the study items. Primacy items were rehearsed more often and further toward the end of the list than middle items, particularly with a slow presentation rate (Experiment 1) and with high-frequency words (Experiment 2). Recency, but not primacy, was reduced by a filled delay (Experiment 3), although significant recency survived a filled retention interval when a fixed-rehearsal strategy was used (Experiment 4). Experimenter-presented schedules of rehearsals resulted in similar serial position curves to those observed with participant-generated rehearsals (Experiment 5) and were used to confirm the main findings in Experiments 6 and 7.     

Diazepam and memory: Support for a duplex model of memory

In three experiments, the hypothesis that diazepam (Valium) selectively impairs the transfer of information from short-term to long-term memory was supported by differences between placebo and drugged subjects in effects of item difficulty, serial position (primacy-recency), and list length. In Experiment 1, diazepam reduced recall in the primacy portion of the serial position function, but produced no performance difference in the recency component. Recall decreased in placebo subjects as item difficulty increased, but drugged subjects were relatively uaffected by manipulation of difficulty. In Experiments 2 and 3, subjects treated with diazepam exhibited smaller gains in immediate recall with increasing list length than placebo controls. Retrieval of words learned before drug administration was not impaired by diazepam; in fact, it was significantly enhanced relative to control performance. The results add further support to the distinction between short- and long-term memory.