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This was demonstrated in experiments by both Postman and Phillips. Serial position. Cognitive Psychology. Postman and Phillips 1965) The Serial Position effect. Consequently, the pronounced recency effect present on the immediate test of recall was progressively reduced as a function of time. By contrast retention of the initial part of the list was relatively stable. These variations in rate of forgetting are attributed to differences among serial positions in susceptibility to proactive. The U-shaped serial position curve is one of the most well-established recall memory findings (Murdock, 1962; Robinson & Brown, 1926; Ebbinghaus, 1913; Nipher, 1876). In contrast, recency (but not primacy) is relativity unaffected by increasing list length or presentation rate (Postman & Phillips, 1965; Murdock, 1962). This is a list of feature films that are based on actual events. Not all movies have remained true to the genuine history of the event or the characters they are. Even more » Account Options. Sign in; Search settings. Download- Theses. Download – Theses. You have not yet voted on this site!

Graph showing the U-shaped serial-position curve, created by the serial-position effect. Serial-position effect is the tendency of a person to recall the first and last items in a series best, and the middle items worst.

The term was coined by through studies he performed on himself, and refers to the finding that accuracy varies as a function of an item's position within a study list. When asked to recall a list of items in any order (), people tend to begin recall with the end of the list, recalling those items best (the recency effect). Among earlier list items, the first few items are recalled more frequently than the middle items (the primacy effect). One suggested reason for the primacy effect is that the initial items presented are most effectively stored in because of the greater amount of processing devoted to them. (The first list item can be rehearsed by itself; the second must be rehearsed along with the first, the third along with the first and second, and so on.) The primacy effect is reduced when items are presented quickly and is enhanced when presented slowly (factors that reduce and enhance processing of each item and thus permanent storage). Longer presentation lists have been found to reduce the primacy effect. One theorised reason for the recency effect is that these items are still present in when recall is solicited.

Items that benefit from neither (the middle items) are recalled most poorly. An additional explanation for the recency effect is related to temporal context: if tested immediately after rehearsal, the current temporal context can serve as a retrieval cue, which would predict more recent items to have a higher likelihood of recall than items that were studied in a different temporal context (earlier in the list). The recency effect is reduced when an interfering task is given. Intervening tasks involve working memory, as the distractor activity, if exceeding 15 to 30 seconds in duration, can cancel out the recency effect. Additionally, if recall comes immediately after test, the recency effect is consistent regardless of the length of the studied list, or presentation rate. With poor ability to form permanent long-term memories do not show a primacy effect, but do show a recency effect if recall comes immediately after study. People with exhibit a reduced primacy effect but do not produce a recency effect in recall.

Contents • • • • • • • • • • Primacy effect [ ] The primacy effect, in and, is a that results in a subject recalling primary information presented better than information presented later on. For example, a subject who reads a sufficiently long list of words is more likely to remember words toward the beginning than words in the middle. Many researchers tried to explain this phenomenon through [null tests].

Coluccia, Gamboz, and Brandimonte (2011) explain free recall as participants try to remember information without any prompting. In some experiments in the late 20th century it was noted that participants who knew that they were going to be tested on a list presented to them would rehearse items: as items were presented, the participants would repeat those items to themselves and as new items were presented, the participants would continue to rehearse previous items along with the newer items. It was demonstrated that the primacy effect had a greater influence on recall when there was more time between presentation of items so that participants would have a greater chance to rehearse previous (prime) items. Overt rehearsal was a technique that was meant to test participants' rehearsal patterns. In an experiment using this technique, participants were asked to recite out loud the items that come to mind. In this way, the experimenter was able to see that participants would repeat earlier items more than items in the middle of the list, thus rehearsing them more frequently and having a better recall of the prime items than the middle items later on. In another experiment, by Brodie and Murdock, the was found to be partially responsible for the primacy effect.

In their experiment, they also used the overt-rehearsal technique and found that in addition to rehearsing earlier items more than later items, participants were rehearsing earlier items later on in the list. In this way, earlier items were closer to the test period by way of rehearsal and could be partially explained by the recency effect.

In 2013, a study showed that primacy effect is also prominent in based on experience in a repeated-choice paradigm, a learning process also known as. The authors showed that importance attached to the value of the first reward on subsequent behaviour, a phenomenon they denoted as. In another study, participants received one of two sentences. For example, one may be given 'Steve is smart, diligent, critical, impulsive, and jealous.' And the other 'Steve is jealous, impulsive, critical, diligent, and smart.'

These two sentences contain the same information. The first one suggests positive trait at the beginning while the second one has negative traits. Researchers found that the subjects evaluated Steve more positively when given the first sentence, compared with the second one. Recency effect [ ] Two traditional classes of theories explain the recency effect.

Dual-store models [ ] These models postulate that later study list items are retrieved from a highly accessible short-term buffer, i.e. The (STS) in human. This allows items that are recently studied to have an advantage over those that were studied earlier, as earlier study items have to be retrieved with greater effort from one’s (LTS). An important prediction of such models is that the presentation of a distractor, for example solving for 10–30 seconds, during the retention period (the time between list presentation and test) attenuates the recency effect. Since the STS has limited capacity, the distractor displaces later study list items from the STS so that at test, these items can only be retrieved from the LTS, and have lost their earlier advantage of being more easily retrieved from the short-term buffer. As such, dual-store models successfully account for both the recency effect in immediate recall tasks, and the attenuation of such an effect in the delayed free recall task. A major problem with this model, however, is that it cannot predict the long-term recency effect observed in delayed recall, when a distractor intervenes between each study item during the (continuous distractor task).

Since the distractor is still present after the last study item, it should displace the study item from STS such that the recency effect is attenuated. The existence of this long-term recency effect thus raises the possibility that immediate and long-term recency effects share a common mechanism. Single-store models [ ] According to single-store theories, a single mechanism is responsible for serial-position effects. A first type of model is based on relative temporal distinctiveness, in which the time lag between the study of each list item and the test determines the relative competitiveness of an item’s memory trace at retrieval.

In this model, end-of-list items are thought to be more distinct, and hence more easily retrieved. Another type of model is based on contextual variability, which postulates that retrieval of items from memory is cued not only based on one’s mental representation of the study item itself, but also of the study context. Since context varies and increasingly changes with time, on an immediate free-recall test, when memory items compete for retrieval, more recently studied items will have more similar encoding contexts to the test context, and are more likely to be recalled.

Outside immediate free recall, these models can also predict the presence or absence of the recency effect in delayed free recall and continual-distractor free-recall conditions. Under delayed recall conditions, the test context would have drifted away with increasing retention interval, leading to attenuated recency effect.

Under continual distractor recall conditions, while increased interpresentation intervals reduce the similarities between study context and test context, the relative similarities among items remains unchanged. As long as the recall process is competitive, recent items will win out, so a recency effect is observed. Ratio rule [ ] Overall, an important observation regarding the recency effect is that it is not the absolute duration of retention intervals (RI, the time between end of study and test period) or of inter-presentation intervals (IPI, the time between different study items) that matters. Rather, the amount of recency is determined by the of RI to IPI (the ratio rule).

As a result, as long as this ratio is fixed, recency will be observed regardless of the absolute values of intervals, so that recency can be observed at all time scales, a phenomenon known as time-scale invariance. This contradicts dual-store models, which assume that recency depends on the size of STS, and the rule governing the displacement of items in the STS. [ ] Potential explanations either then explain the recency effect as occurring through a single, same mechanism, or re-explain it through a different type of model that postulates two different mechanisms for immediate and long-term recency effects.

One such explanation is provided by Davelaar et al. (2005), who argue that there are between immediate and long-term recency phenomena that cannot be explained by a single-component memory model, and who argues for the existence of a STS that explains immediate recency, and a second mechanism based on contextual drift that explains long-term recency. Related effects [ ] In 1977, decided to outline a study to further the previous conclusions on the nature of order effects, in particular those of primacy vs.

Recency, which were said to be unambiguous and opposed in their predictions. The specifics tested by Crano were: Change of meaning hypothesis The items on the beginning of a list establish a theme that the participants expect the rest of the list to fall into.

The participant modified the meaning of some of the words on the list to fit with the expectation he or she established. Watkins and Peynicioglu (1984) explain this as participants changing the meaning of words, deviating from the established theme, to reduce the amount of deviation in the information presented. Inconsistency discounting Participants would disregard information that was not consistent with previous items presented to them.

In other words, discounting involves thinking of inconsistent information as having less value than information that is consistent with other information presented (Devine & Ostrom, 1985). Attention decrement hypothesis Information presented first has a greater influence on participants than information that is presented later, causing a primacy effect to occur, even if the information is consistent. Steiner and Rain (1989) explain people pay more attention to information presented at the beginning, but progressively pay less attention to the information presented to them. The primacy effect occurs because participants pay attention to the beginning information and ignore the information presented later.

On the other hand, if participants are in a situation where they have to continuously pay attention to information, a recency effect may occur. The continuity effect or lag-recency effect predicts that having made a successful recall, the next recalled item is less likely to come from a remote serial position, rather than a nearby serial position (Kahana, Howard, Zaromb & Wingfiend, 2002). The difference between the two items' serial position is referred to as serial-position lag.

Another factor, called the conditional-response probability, is the likelihood of recalling a certain serial-position lag. A graph of serial-position lag versus conditional response probability reveals that the next item recalled minimizes absolute lag, with a higher likelihood for the adjacent than the previous one. See also [ ] • • • • • • • • • • • Notes [ ]. • Coleman, Andrew (2006). Dictionary of Psychology (Second Edition).

Oxford University Press. • Ebbinghaus, Hermann (1913). On memory: A contribution to experimental psychology. New York: Teachers College. • Deese and Kaufman (1957) Serial effects in recall of unorganized and sequentially organized verbal material, J Exp Psychol. 1957 Sep;54(3):180-7 • ^ Murdock, Bennet (1962). Journal of Experimental Psychology.

64 (5): 482–488.. • Howard, Marc W.; Michael J. Kahana (2002). 'A Distributed Representation of Temporal Context'. Journal of Mathematical Psychology.

46: 269–299.. • Bjork, Robert A.; William B.

Whitten (1974). 'Recency-Sensitive Retrieval Processes in Long-Term Free Recall'. Cognitive Psychology. • Murdock, Bennet; Janet Metcalf (1978). 'Controlled Rehearsal in Single-Trial Free Recall'.

Journal of Verbal Learning and Verbal Behavior. 17: 309–324.. • Carlesimo, Giovanni; G.A.

Caltagirone (1996). 'Recency effect in anterograde amneisa: Evidence for distinct memory stores underlying enhanced retrieval of terminal items in immediate and delayed recall paradigms'.

34 (3): 177–184.. • Bayley, Peter J.; David P. Salmon; Mark W. Bondi; Barbara K. Bui; John Olichney; Dean C. Delis; Ronald G.

Thomas; Leon J. Thai (March 2000).

'Comparison of the serial-position effect in very mild Alzheimer's disease, mild Alzheimer's disease, and amnesia associated with electroconvulsive therapy'. Journal of the International Neuropsychological Society. 6 (3): 290–298.. • Glenberg, A.M; M.M. Bradley, J.A.

Stevenson, T.A. Tkachuk, A.L.

Gretz (1980). 'A two-process account of long-term serial position effects'. Journal of Experimental Psychology: Human Learning and Memory.

CS1 maint: Multiple names: authors list () • Marshall, P.H.; P.R. Werder (1972). 'The effects of the elimination of rehearsal on primacy and recency'. Journal of Verbal Learning and Verbal Behavior. 11: 649–653.. 'Maintenance rehearsal and long-term recency'. Memory and Cognition (8(3)): 226–230.

• Rundus, D (1971). 'An analysis of rehearsal processes in free recall'. Journal of Experimental Psychology.

• Brodie, D.A.; B.B. 'Effects of presentation time on nominal and functional serial-position curves in free recall'. Journal of Verbal Learning and Verbal Behavior. 16: 185–200.. • Shteingart, Hanan; Tal Neiman; Yonatan Loewenstein (2013). Journal of Experimental Psychology: General. 142 (2): 476–488...

• Asch, S (1946). 'Forming impressions of personality'. Journal of Abnormal and Social Psychology.

41: 258–290.. • ^ Bjork & Whitten (1974). Recency sensitive retrieval processes in long-term free recall, Cognitive Psychology, 6, 173–189. 'Sources of recency effects in free recall'. Psychological Bulletin.

99 (12): 221–228.. • Neath, I.; Knoedler, A.

'Distinctiveness and serial position effects in recognition and sentence processing'. Journal of Memory and Language. 33: 776–795.. W.; Kahana, M. 'Contextual variability and serial position effects in free recall'. Journal of Experimental Psychology: Learning, Memory and Cognition.

24 (4): 923–941.. W.; Kahana, M. 'A distributed representation of temporal context'. Journal of Mathematical Psychology.

46 (3): 269–299.. • Davelaar, E.

K.; Goshen-Gottstein, Y.; Ashkenazi, A.; Haarmann, H. J.; Usher, M. 'The demise of short-term memory revisited: Empirical and computational investigations of recency effects'.

Psychological Review. References [ ] • Coluccia, E.; Gamboz, N.; Brandimonte, M. 'Normative data for a battery of free recall, cued recall and recognition tests in the elderly Italian population'. 32: 1103–1114..

• Frensch, P.A. 'Composition during serial learning: a serial position effect'. Journal of Experimental Psychology: Learning, Memory, and Cognition. 20 (2): 423–443.. • Healy, A.F.; Havas, D.A.; Parkour, J.T.

'Comparing serial position effects in semantic and episodic memory using reconstruction of order tasks'. Journal of Memory and Language. 42: 147–167.. W.; Kahana, M. 'Contextual Variability and Serial Position Effects in Free Recall'.

Journal of Experimental Psychology: Learning, Memory & Cognition. 25 (4): 923–941.. J.; Howard, M.

W.; Polyn, S. 'Associative Retrieval Processes in Episodic Memory'. J.; Howard, M. W.; Zaromb, F.; Wingfield, A. 'Age dissociates recency and lag recency effects in free recall'. Journal of Experimental Psychology. 28: 530–540..

Further reading [ ] • Liebermann, David A. Learning and memory: An integrative approach.

Belmont, CA: Thomson/Wadsworth, 2004,.

The occurrence of primacy versus recency effects in free recall is suggested to reflect either two distinct memory systems, or the operation of a single system that is modulated by allocation of attention and less vulnerable to interference. Behavioral and event-related brain potential (ERPs) measures were used to investigate the encoding substrates of the serial position curve and subsequent recall in young adults. Participants were instructed to remember lists of words consisting of 12 common nouns each presented once every 1.5 sec, with a recall signal following the last word to indicate that all remembered items should be written on paper. This procedure was repeated for 20 different word lists. Both performance and late ERP amplitudes reflected classic recall serial position effects. Greater recall and larger late positive component amplitudes were obtained for the primacy and recency items, with less recall and smaller amplitudes for the middle words. The late positive component was larger for recalled compared to unrecalled primacy items, but it did not differ between memory performance outcomes for the recency items.

The close relationship between the enhanced amplitude and primacy retrieval supports the view that this positive component reflects one of a process series related to attentional gradient and encoding of events for storage in memory. Recency effects appear to index operations determined by the anticipation of the last stimulus presentation, which occurred for both recalled and unrecalled memory items. Theoretical implications are discussed. Serial Position Memory The U-shaped serial position curve is one of the most well-established recall memory findings (;;; ). After a list of words is presented, recall performance is greater for items from the beginning (primacy effect) and end (recency effect) compared to items presented in the middle of a list (; ). The classic theoretical interpretation is that primacy memory effects occur for initial list items that are encoded and relatively well rehearsed, thereby promoting transfer from short-term storage to long-term memory.

Subsequent retrieval is enhanced compared to items in the middle of the list, as these items are not rehearsed as strongly as the initial items. Recency effects occur because the just-presented list items are encoded in the short-term store and are immediately available for output when the end of the list signals that retrieval is required (; ). Experimental manipulations of stimulus presentation speed that affect only primacy items and postlist interference tasks that affect only recency items strongly support this view (;; ).

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An alternative interpretation is that, because initial items have minimal interference from preceding items and final items have no interference from subsequent items, both primacy and recency effects reflect the operation of a single memory system (; ). An influential model of serial position memory effects posits an attentional primacy gradient. During encoding the amount of attention devoted to each stimulus is reduced across successive serial positions, such that each successive stimulus receives less attention than the previous one (; ). Hence, items presented at the beginning receive more attention and produce a stronger neural trace. As a result, retrieval for stimuli presented first is better compared to stimuli in the subsequent positions. An alternative theoretical mechanism for producing both primacy and recency effects is interference (; ). An initial memory trace is sensitive to interference so that the stimulus memory traces for middle items are subject to more interference as additional subsequent items are presented.

Thus, initial items have no interference from preceding items and final items have no interference from subsequent items so that retrieval performance is enhanced as primacy and recency positions are less affected by interference. Memory and Event-related Potential Effects Event-related potential (ERP) assessment of recall memory was initially conducted to determine whether P300 amplitude was associated with recall performance (,; ). Lists of words presented sequentially and ERPs were recorded. In some lists, one of the words was presented either in smaller or larger font size than the other words so that stimulus distinctiveness would affect encoding and facilitate recall memory. Distinct word stimuli that were subsequently recalled elicited larger P300 components during encoding than those that were not recalled. However, P300 amplitude was directly affected by the rehearsal strategy, such that component amplitude was larger for subsequent recall when participants used rote rehearsal ().

When participants employed an elaborative strategy for memorization, the variance in the P300 amplitude was not associated with subsequent recall. Taken together, these findings suggested that some aspect of the P300 amplitude reflects the strength of neural activity related to memory modification (). Serial Position Memory and Event-related Potential Effects Serial position effects assessed with ERP methods have typically employed memory scanning recognition rather than recall procedures. After memorizing a list of items, a probe stimulus is presented with the instruction to indicate whether that item was from the memory set. A robust finding is that probe stimuli from the last serial position produce shorter response times and larger P300-like components than those from the middle (; ). The results are consistent with behavioral serial position findings that suggest retrieval is affected by how the stimulus items are encoded and accessed when recall is engaged (). Neuroimaging studies also indicate that retrieval of previously studied events reactivates brain regions active during encoding of the same events ().

Taken together, behavioral and neuroimaging studies agree with ERP findings that serial position effects from recognition tasks appear to depend on the strength of memory formed during encoding and storage processes. These proposed recognition mechanisms are likely to be operating when probe assays of serial position are used to elicit ERPs, with relatively large P300 amplitudes obtained for recency items rather than earlier probes (; ). Indeed, P300 amplitude increases linearly from probe stimuli of the initial to ending list items, suggesting that recognition primacy and recency effects reflect different processing mechanisms (). To date, the majority of studies have assessed serial position in the auditory modality, with no evidence currently available that similar recognition serial position ERP effects occur for visual probes. Given that serial position effects could be modality dependent (; ), how visual stimulus ERPs may vary across serial position is unclear.

ERPs and serial position at the time of encoding have been studied, with participants instructed to use elaborative learning strategy to chunk the words in groups comprised of three or five items (). ERP comparisons were made between recalled and unrecalled words for each segment of the serial position curve corresponding to primacy, middle, and recency areas. The major finding was that early ERPs were modulated according to serial position and subsequent recall: Primacy recall was associated with increased P1 and P2 amplitudes, whereas recall at the middle positions only demonstrated increased P1 amplitude. Although behavioral recall performance varied in the typical way for both primacy and recency positions, ERPs were modulated only by primacy effects and did not reflect recency effects. Indeed, no consistent P300 amplitude effects were obtained for free recall across serial positions. It is important to note that participants were specifically instructed to utilize different elaborative strategies across two sessions.

In one session, they formed sentences from three words, and in the other they formed sentences from five words. However, the results were analyzed and reported on the basis of the summation of these two strategies. These ERP serial position findings, therefore, do not directly address the primacy versus recency memory issue. Present Study The present study extends previous ERP serial position tasks by obtaining behavioral and ERP measures in the classic word list recall task and averaging separately over correctly recalled and unrecalled items for each portion of the list.

It is hypothesized that the electrophysiological correlates of serial position should exhibit selective modulations for items presented in the primacy and recency positions compared with the items presented in the middle of a memory set. Theories based on behavioral findings suggest that primacy effects result from more attention allocation to items presented in the beginning of a list compared to the subsequent items (; ). One approach to investigate the link between allocation of attention and primacy effect is to characterize how the P3 component varies across memory for serial position items. If primacy effects index greater allocation of attention, the P3 amplitude elicited by items initially presented should be larger compared to items presented in other positions. The present study was explicitly designed to assess encoding processes that determine successful retrieval in free recall. It is hypothesized that retrieval of more recently presented items indexes the maintenance of items in working memory to promote subsequent access in the absence of interference or delay (; ). If recency operations are unrelated to encoding and reflect maintenance of items in short-term memory, then little difference should be obtained between ERPs from the recency and middle items.

Stimuli Stimuli consisted of 240 words with high frequency (28.1 per million) selected from. The stimuli varied in length between five and seven letters and were organized into 20 lists of 12 words each. The study word lists were randomly ordered and counterbalanced across subjects using five different orders. Each list was constructed to eliminate random occurrence of conceptually related words grouped in serial positions. All stimuli were presented on a monitor 100 cm in front of the participant. Each word was presented at the center of the screen in red lowercase letters (Arial 28 font) on a black background. A separate pool of 12 words was used for the practice test.

Procedure illustrates the experimental paradigm. A single word was presented for a duration of 250 msec and an interstimulus interval of 1500 msec, with each of the 12 words in each list presented only one time. Before each list, three presentations of the characters XXXX occurred; after the last word of each list, the same character string was presented to signal stimulus recall.

Participants were instructed to memorize the words for a recall test that would immediately follow. The subjects were not required to use any specific encoding strategies and were instructed to adapt methods that would produce maximal retrieval. Participants then were instructed to write the words just presented in any order on a sheet of paper. Recall time was 60 sec and the recall sheet was collected at the end of this time.

After a brief rest, the next recall list was presented in the same fashion until all 20 lists had been viewed in about 2.5 hr. The number of lists presented was determined by extensive pilot work, with 20 word lists found to be the maximum before excessive fatigue occurred. Photoscore Ultimate 7 Keygen Mac more. Recording Conditions Electroencephalographic (EEG) activity was recorded from 19 electrodes that included Fz, Cz, Pz, F1/2, F3/4, F7/8, C3/4, T7/8, P3/4, P7/8, O1/2, referred to balanced linked earlobes, with a forehead ground and impedance at 10 kΩ or less. Additional electrodes were placed at the outer left canthus and below the left eye to measure electrooculographic (EOG) activity with a bipolar recording. The bandpass was 0.01–30 Hz (6 dB octave/slope), and the EEG was digitized at 4.0 msec per point for 1024 msec, with a 100-msec prestimulus baseline. Waveforms were averaged off-line, and trials on which the EEG or EOG exceeded ±100 μV were rejected. An EOG correction procedure was employed to remove any remaining artifact ().

Data Analysis The behavioral and ERP data were analyzed statistically in the same general fashion. Each dependent variable was obtained for each of the 1 to 12 serial positions. ERP waveforms from each serial position for each subject were averaged over the single trials from words that were correctly recalled and those that were unrecalled (i.e., not correctly recalled). The mean behavioral values and ERPs from serial positions 1–3, 4–6, 7–9, and 10–12 for the recalled and unrecalled words from each list for each subject were then used for subsequent analyses and will be termed serial position blocks 1, 2, 3, and 4, respectively. This approach was adopted to facilitate their presentation and statistical evaluation after preliminary analyses of list positions 1 to 12 did not differ substantially from the grouping of averages into four blocks. To assess possible differential signal-to-noise contributions to the ERP averages after artifact rejection, the number of trials for each ERP average from each subject within the four serial position blocks for each memory outcome was determined. The mean number of trials in each serial position block for the recalled items was 27.8, 18.6, 17.6, 20.8, and for the unrecalled items was 11.9, 18.6, 16.2, 12.7, respectively.

A two-factor (2 recall outcomes × 4 serial position blocks) analysis of variance (ANOVA) found more trials obtained for the recalled than unrecalled words, reliable differences among the serial positions, and a significant interaction ( p. Behavioral Performance illustrates the mean percentage of recalled items for each serial position block.

A one-factor (4 serial position blocks) ANOVA indicated that the proportion of words correctly recalled differed among the blocks [ F(3, 87) = 18.9, p.75). Thus, the behavioral recall data demonstrated a serial position curve. Event-related Potential Serial Position Recall Effects illustrates the grand averages for the recalled and unrecalled words for each serial position block from the midline electrodes. Waveform measures were defined as the negative and positive area voltage within early 250–500 msec and late 500–750 msec latency windows, respectively, obtained from each electrode.

This approach was based on visual assessment of the data and previous ERP memory studies that found early and late waveform effects (;; ). Early (250–500 msec) Window illustrates the early window mean negative area voltage for the recalled and unrecalled words from the midline electrodes as a function of serial position block from the midline electrodes. Illustrates the topographic distribution of the area voltage within the window. Recalled items produced more negativity than unrecalled items overall [ F(1, 29) = 4.4, p. Mean recalled (left) and unrecalled (right) early negative amplitude as a function of serial position block for the midline electrodes. Assessment of the individual electrodes found marginally more negativity for recall relative to unrecalled words for each of the midline electrodes ( p.85) or recency ( F = 1.8, p >.15) serial position effects.

Planned comparisons found a reliable primacy effect at Cz for correctly recalled items, as serial position block 1 produced less negative area than serial position block 2 [ F(1, 29) = 6.04, p.75), with a marginal recency serial position effect obtained [ F(1, 29) = 3.3, p. Late (500–750 msec) Window illustrates the early window mean positive area voltage for the recalled and unrecalled words as a function of serial position block from the midline electrodes. Illustrates the topographic distribution of the area voltage measure within the window. The same ANOVA structure used for the early window was applied to the later 500–750 msec positive amplitude data.

Recalled items produced larger positive areas than unrecalled items [ F(1, 29) = 15.3, p.15]. Positive area increased in magnitude from the frontal to parietal (i.e., the waveform became larger from the frontal to parietal) electrode locations [ F(2, 58) = 24.3, p. Mean recalled (left) and unrecalled (right) late positive amplitude as a function of serial position block from the midline electrodes. Assessment of the individual electrodes revealed that recalled items had larger positive areas than unrecalled items for the Fz [ F(1, 29) = 10.3, p.30). Recalled items produced no reliable recency area differences between serial positions 3 and 4 ( F = 2.7, p >.10). However, unrecalled items evinced a reliable recency difference between positions 3 and 4 [ F(1, 29) = 5.53, p. Discussion The present study employed ERPs to examine serial position memory effects.

Recall performance produced a serial position curve, with a greater percentage of words found for the primacy and recency items than for middle serial positions. The main ERP results were: (1) Early negative amplitude areas (250–500 msec) demonstrated a relatively weak recalled versus unrecalled difference, and memory outcome did not interact with serial position block. (2) Larger late positive amplitude areas (500–750 msec) were obtained for the correctly recalled compared to the unrecalled items. (3) Larger areas over the parietal sites for this measure were found in the primacy serial positions for recalled compared to unrecalled items, whereas recency area measures did not differ between memory outcomes. The findings indicate that negative–positive modulations at the primacy position reflect the encoding strength and whether a word will be recalled correctly. Although the P3 component may not be a direct index of storage processes, memory for items that elicit a P3 is better than items that do not elicit a P3, even under task conditions that require immediate or delayed retrieval (; ).

The close relationship of P3 amplitude and delayed retrieval also supports the view that the component is one of the series of processes that reflect the encoding of events for storage in memory. With respect to recency effects, no distinction between recalled and unrecalled items was observed, as these behavioral outcomes were both associated with a robust P3. Furthermore, recall performance for the primacy items was greater than recall at the recency position. Taken together, these P3 results support a distinction between primacy and recency memory operations during encoding. Recall Event-related Potential Primacy Effects Previous studies have demonstrated a strong relationship between encoding processes and subsequent retrieval (;;; ). The primacy effect from serial position recall reflects this association, as recall for items in the beginning of the list is greater even though early items are vulnerable to decay and interference from later items (). The primacy gradient model postulates that items presented in the beginning of a list receive more attention during the encoding stages of processing than later items (; ).

In a homogenous sequence, each new item is less surprising and the strength of attention declines across successive trials (; ). The link between attention and depth of encoding therefore produces stronger retrieval performance for items presented in the initial compared to subsequent serial positions. The mediating effect of attention on enhanced recognition is further supported when subjects study the items with full attention compared to those with divided attention (). These findings also are consonant with results that suggest words studied with full attention are recognized with more confidence and associated with greater P300 amplitude (). Primacy position encoding effects were associated with larger late positive amplitudes relative to items in the middle serial positions, with the ERP waveforms for correctly recalled primacy items larger than unrecalled items.

Hence, the strength of encoding underlies successful storage of information into memory and can index subsequent retrieval. In the primacy position, the cognitive and neural processes associated with these functions were dissociated predominately in the positive-going deflection of ERP waveforms.

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P300 amplitude is affected by attentional resources with relatively easy tasks yielding larger components than difficult tasks (; ). During retrieval of the initial list items that were relatively easy to encode and store compared to other items, enhanced positive amplitude for primacy items was obtained, which is perhaps related to P300 activity.

The late positive amplitude may index memory trace strength formed during encoding. Indeed, increases in memory load reduce P300 amplitude in a manner that suggests fewer attentional resources are engaged because of increased task demands to process these items (;; ). Retrieval did not produce amplitude variation of the early ERP components, which is inconsistent with findings that primacy recall is associated with increased P1 and P2 amplitudes (). Recall Event-related Potential Recency Effects The superior retrieval for items at the recency position appears to reflect maintenance and direct output of these items from short-term memory ().

When participants are instructed to perform a distraction task or delayed free recall, the recency effect is strongly attenuated (). In contrast, recency (but not primacy) is relativity unaffected by increasing list length or presentation rate (; ). Behavioral and computational studies have delineated storage and retrieval processes of recency memory, although the neural activity elicited for recency items is unclear (;; ). Consistent with the behavioral results, larger late positive amplitude was found for the recency for both recalled and unrecalled items. This outcome stands in contrast to the primacy gradient hypothesis, which predicts that recency position items receive less attention and more interference than items in preceding positions.

As list presentation progresses, rehearsal of previous items and memory overload disturbs encoding of additional items. Encoding of items in the recency position should therefore yield a decrease in late positivity area.

Given the observed larger ERP amplitude at the recency serial positions, participants likely knew when the memory set would end, so that recency items were associated with a temporal cue for recall. This hypothesis was explored only in subset of participants ( n = 11) that were asked to guess the number of words in each list. Estimates ranged from 8 to 14 words per list, with two subjects reporting the exact number (12). The majority of these participants reported that they sensed the presentation of the last item or felt that the list was about to end. The enhanced positive amplitude may therefore reflect neural activity associated with anticipation of the last stimulus presentation, which would have occurred for both recalled and unrecalled memory items.

This interpretation is consonant with ERP studies that find a similar enhanced positivity for cue stimuli that index cognitive shifts induced by such tasks as the Wisconsin Card Sorting Test (; ). As noted, the primacy ERP outcomes for recalled and unrecalled items were distinguishable, as the primacy effects differed but the recency effects were similar across both recalled and unrecalled items. The discrepancy may indicate that the enhanced positivity for primacy items reflects serial position encoding and memory storage, whereas recency items were limited to just encoding.

This outcome is likely because the difference between recall memory for items in primacy and recency positions could stem from interference and memory overload (; ). Hence, there may be greater flexibility during encoding of primacy items, whereas recency items are encoded less independently of previous storage operations. In the beginning of the list, there are few items competing for attention, and this process strengthens encoding and memory for the primacy items.

However, rehearsal and interference from earlier items prevent in-depth encoding of items in the recency positions. In addition, items in the beginning of the list are unaffected by restrictions of memory capacity, whereas items in the recency positions would suffer from memory overload. These processes, therefore, could affect recency items, such that anticipation of the list ending would underlie the obtained ERP serial position effect. Early Versus Late Effect ERP correlates of memory have been demonstrated to consist of early and late components distinguished by their topography and temporal characteristics (; ). The early effect is a negative deflection commonly elicited by complex and meaningful stimuli (; ), which begins about 300–400 msec post-stimulus onset and is maximal in the frontal electrode sites (; ). This component has been associated with learning, and declines with stimulus repetition as items become familiar (). Consistent with previous findings, the present study found relatively small negative deflections over frontal sites that were followed by larger positive voltage increases over parietal sites (; ).

The negative-going deflection was slightly larger for unrecalled compared to recalled items and did not differ between the recalled versus unrecalled items in other serial positions. These observations may indicate that encoding items at the primacy position is a two-part process that occurs during early and late intervals (). The early negativity may index the initial stage of encoding and the late positivity may reflect the strength of memory trace formed at that time. The functional relationship between the negative and late positive component is uncertain, but the pattern of ERP modulation appears to index distinct neural processes associated with encoding and memory formation. Recency Versus Primacy Retrieval In contrast to several earlier studies, the present study found that recall performance was superior for primacy rather than for the recency portion of the curve (; ). The traditional interpretation for recency advantage is that these items are highly accessible and insensitive to decay.

Recency effects can be impaired when participants are forced to perform a distracting task after the last item before the signal to begin recall (). It is unlikely that the XXXX signal stimulus that occurred at the end of each memory set produced interference with recency retrieval. Indeed, the end-signal stimulus purposefully was included after extensive pilot testing by comparing conditions with and without an end-signal stimulus, with the strong observation that the absence of an end-signal stimulus to begin recall impaired retrieval for the very last item. In addition, and although findings differ, several studies suggest that the capacity of storage for primacy portion of the curve is greater than recency (; ). Further, preliminary analyses of the separate 1–12 serial positions individually demonstrated a primacy relative to recency advantage.

Thus, the present paradigm is consistent with previous findings and the dictates of the paradigm employed. The relatively small discrepancy between the shape of the classic serial position curve and the present finding also may be related to the presentation and retrieval modality. The participants were presented with a visual word that was presumably encoded in a verbal form and behaviorally recorded in a written form. In the majority of classic serial position studies, participants were presented with auditory stimuli and received instructions to retrieve the items orally (, ). It therefore seems likely that different systems are employed for retrieving auditory compared to written retrieval, and that these differences can produce serial position curves so that retention of items in the primacy exceeded those in the recency position. Functional Neuroimaging and Serial Position Previous research implies a dual-storage model of primacy and recency, although link between these processes and its neural substrates is still speculative.

The advent of functional magnetic resonance imaging (fMRI) has identified some of the brain mechanisms mediating the serial position curve (; ). In general, the findings indicate a functional distinction for primacy and recency retrieval on the basis of anatomy and activation patterns. One fMRI study demonstrated that primacy probes generated activation in the left hippocampal regions, whereas recency probes increased activation in the inferior parietal lobe and premotor cortex (). Additional fMRI evidence implicates the involvement of the hippocampus in long-term storage processes, such that hippocampal activation appears selective for primacy but not recency retrieval thereby enhancing long-term memory storage for primacy items (; ).

This interpretation is consistent with the proposal that primacy items engage more rehearsal to increase long-term memory processing (; ). In contrast, recent memory items are stored on a temporary basis and activate areas that only contribute to short-term storage (; ).

Vic's audio system:

I use the front end as part of a home theatre set up, but wont go into detail as I’m mainly concerned with the stereo aspect of the system.

I made the hi-fi unit from kitchen worktops and a pair of IKEA units.

Speakers are Kef 107’s updated to Mk2.

Amplifier is from Affordable Valve Company ( http://www.affordablevalvecompany.com ) which uses KT88’s in triode connection and is rated at 20W/channel. This amplifier brought the system to life in terms of sweetness, soundstage, dynamics and bass. The amp is made in China to UK specs.

Turntable is my pride and joy. A heavily tweaked Michell Gyrodec with the Pedersen http://pedersensgyro.hjem.wanadoo.dk/index_english.htmand Orbe mods.

Tonearm is a home made no frills parallel tracking air bearing arm made from carbon fiber and aluminum channeling, powered with an aquarium pump. The design was inspired by Paul Ladergaard(http://www.aiko.com/roscoe/airbearingarm.html). It works fantastically well.

Cartridgeis the one and only Music Maker. A moving magnet design with moving coil sound. Brilliantly detailed, open and spacious. Works really well with the Ladergaard arm. (http://www.listen.to/thecartridgeman)

Phono Preamp is the EAR 834P with up-rated valves.

I haven’t invested in cabling having yet to be shown an appreciable difference to the cheap cables I’m using at present.

Additional comments about the arm:
I love the Ladergaard arm. All I can tell you is the system sounds the best it ever has. I cant compare direct to the Rega 250 (Origin Live) I was using before because I changed to the Music Man (cartridge) at the same time. I was getting low frequency rumble with the Rega and MM combination....I think some resonance incompatibility??? So it didn't last long. I was surprised how easy the arm (Ladergaard) was to make, and how well it worked. It is so sensitive, and will not tolerate any level changes. They advised not use it on a suspended TT, by I went ahead anyway, and it worked! I have now stiffened the suspension anyway with the Petersen mods (which were tricky!) which really cleaned and noticeably tightened things up so I can now hear the timbre and tones within Stings bass technique. Fantastic. I got a similar improvement after doing the shelf, so now am really delighted.

Above 4 thumbnails detail the diy TT bracket. Click to see full size image.

Ear 834p Manual

Vic's comments on making the turntable bracket:
I modified a pair of microwave brackets by adding a triangular support. The shelf supports a 4cm piece if kitchen worktop. This is sandwiched between two pieces of 3/4' MDF and foam inserts. On top of that lies a 1' slate slab. This is separated by polyurethane pipe insulation which I slices into 1cm discs. On top of this rests the Gyro!
Sounds a looks great.

Ear 834p Owners Manuals

System Strengths are the open detail, wide soundstage, sweet highs and tight, deep controlled bass.

Weakness' are limited watts…..but I don’t listen too loud, and the system is not forgiving of hard, compressed material. I have a few Police and Dire straits albums which are brilliantly recorded.

Am using a Sony DVD/ SACD player, but haven’t invested heavily in this preferring the sound of vinyl. Am waiting for AVC to release their valve CD player, which seems full of promise!

Regards,

Ear 834p Kit

Vic