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Serial memory processing

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Serial memory processing is the act of attending to and processing one item at a time. This is usually contrasted against parallel memory processing, which is the act of attending to and processing all items simultaneously. In short-term memory tasks, participants are given a set of items (e.g. letters, digits) one at a time and then, after varying periods of delay, are asked for recall of the items. As well, participants could be asked whether a specific target item was present in their original set.[1]

Overview

Serial memory processing uses internal representations of the memory set in order to compare them to a target stimulus. These internal representations are then compared to the target stimulus, one at a time. Reaction Time increases linearly with the set size, where the more items in the memory set, the longer it will take to compare. [2]

Serial memory processing can be either Self-Terminating or Exhaustive. Self-Terminating implies that comparisons stop abruptly as soon as the target is found, and then the response is generated. [1] Evidence for this method is found in reaction time studies. If the reaction time slope for a positive trial (where the target was present in the memory set) is about half of the slope for a negative trial (where the target was not present in the memory set) this demonstrates self-terminating processing. This is because, on average, participants (on positive trials) will stop comparisons about halfway through when they find the target match but participants (on negative trials) will need to compare until the end when no target match is found. [3] On the other hand, Exhaustive implies that comparisons continue until the entire set is compared and then a response is generated. [1] Evidence for this method is also found in reaction time studies. In this case, the reaction time slope is equal for both positive and negative trials, as comparisons are made to the end in both cases. [2]

Characteristics of processing

Primacy and recency effects

In serial memory processing, Primacy effect and Recency effect effects for accuracy of recall are commonly found. These effects are found for both visual and auditory stimuli in memory tasks. [4] These effects may exist if recall errors are due to serial position. There are more nearby serial positions to middle items in a set, and therefore more opportunities for mix-up. On the other hand, there are very few serial positions nearby to the first and last position, and therefore these positions may be remembered more accurately. The first and last position may be less error-prone positions and more easily recalled. [5]

The suffix effect, is an effect that removes the recency effect, simply by adding in a meaningless item at the end of the original memory set. However, the suffix effect varies based on the similarity of the item to the set. For visual stimuli, adding in the meaningless item, whether or not it is visually similar to the original memory set, will remove the recency effect. For auditory stimuli, adding in the meaningless item will only remove the recency effect if it is phonologically similar. Adding an item that is phonologically different (e.g. A, Q) will not have this effect. [6]

Stimuli grouping effects

Items in a serial memory can be presented in ways that promote grouping. Individuals can group the memory items spatially and temporally. [4]

Spatial grouping refers to the items in the original memory set being grouped by their spatial characteristics. An example of this would be presenting the first three items in the top right corner, and the remaining three items in the bottom left corner. These items are now grouped into two groups of three based on their spatial attributes. As well, it has been found that the longer the spatial pathways from item to item, the slower the recall time and the lower the accuracy of recall. Therefore, item’s that have a small spatial pathway between them, are remembered better and faster. [4]

Temporal grouping refers to the items in the original memory set being grouped by their temporal characteristics. An example of this would be presenting the first three items simultaneously, then waiting five seconds, and then presenting the remaining three items. These items are now grouped into two groups of three based on their temporal attributes. It has been found that when item’s are grouped temporally, the accuracy of recall is higher than when they are not. As well, there is evidence that participants may create their own temporal groupings. In a memory task where items were not temporally grouped, the reaction times of recall for the 1st, 4th and 7th (out of 9) items were significantly faster. Showing evidence for participants creating their own temporal group of three. [4]

Other errors

There are other errors that exist in serial memory tasks. Serial position errors have been discussed earlier, in relation to the primacy and recency effect. These errors have been found to be independent from other errors, such as acoustic errors. Acoustic errors result from items that are phonologically similar. An example of this would be recalling “B” as opposed to the actual item “P”. These items are phonologically similar and can cause acoustic errors. These are related to the suffix effect as well, which found that the rececny effect was only removed when phonologically similar stimuli were used. [7]As well, other variables of verbal stimuli have been found to cause acoustic errors. Examples of these variables are word length, word frequency and lexicality. These interact to cause acoustic errors in serial memory tasks. [8]

Processing in atypical individuals
  • When mental age is equal, no difference on serial memory tasks or children with autism [9]
Neuro-perspective
  • Prefrontal cortex and Hippocampus related to serial memory processing. Lesions in these areas are related to impaired ability to remember temporal order [10].
  • Rats with lesioned prefrontal cortex's can only remember the first item in a set of 2. As well, the rats increase their corticosterone when experiencing stress during a serial memory task [11].
  • Rats with lesioned hippocampal region's can only remember the second item in a set of 2. However, they do not increase their corticosterone when experiencing stress during the serial memory task [11].
  • LH found to be better at serial processing and serial memory comparison than RH [12].

Associated models

  • ACT-R is Adaptive Control of Thought-Rational. This model help to hierarchically organize serial memory. In this model, declarative memory works to encode the position of items while the production memory works to organize recall of items. This is a limited-capacity model, where there is a limited amount of activation available. This theorizes that longer memory sets lead to longer recall because the amount of activation available is divided among more items. The ACT-R models the serial position error [5] and the independent acoustic errors [7] near perfectly. [13]
  • Sternberg's (1969) model of item recognition. In this model, item recognition follows several steps. First the test stimulus is presented and then the stimulus is encoded. Next, serial comparisons are completed (these are affected by the size of the memory set) and a binary decision is made on each comparison (e.g. positive, negative). Finally, a response is organized and expressed. [3].
  • Stimuli confusability can affect item recognition. Auditory confusability in the memory set increased encoding time and visual confusability in memory set increased comparison time [14].

Article briefs

  • Serial/Parallel [1]
  • Serial Processing Overview [2]
  • More Serial Processing Overview [3]
  • Spatial and Temporal Grouping effect [4]
  • Serial Memory in Children with Autism [9]
  • Brain Areas [10]
  • More Brain Areas [11]
  • Primacy/Recency Effects [15]
  • Serial Memory Encoding [14]
  • Forgetting Curve / Uncertainty Gradient [5]
  • Acoustic Confusions [7]
  • ACT-R Model, related to Ref. 4,10, 11** [13]
  • Effects on Serial Memory Errors [8]
  • Suffix Effect [16]
  • Hemispheric Laterality [12]

References

  1. ^ a b c d Townsend, J. & Fific, M. (2004). Parallel versus serial processing and individual differences in high-speed search in human memory. Perception & Psychophysics, 66(6).
  2. ^ a b c Sternberg, S. (1966). High-speed scanning in human memory. Science, 153(1).
  3. ^ a b c Sternberg, S. (1969). Memory-scanning: Mental processes revealed by reaction-time experiments. American Scientist, 57(4).
  4. ^ a b c d e Parmentier, F. B., Andres, P., Elford, G., & Jones, D. M. (2006). Organization of visuo-spatial serial memory: Interaction of temporal order with spatial and temporal grouping. Psychological Research, 70(1).
  5. ^ a b c Nairne, J. S. (1992). The loss of positional certainty in long-term memory.Psychological Science, 3(3).
  6. ^ Cite error: The named reference Parmentierr was invoked but never defined (see the help page).
  7. ^ a b c Bjork, E. L., & Healy, A. F. (1974). Short-term order and item retention. Journal of Verbal Learning and Verbal Behavior, 13(1).
  8. ^ a b Burgess, N., & Hitch, G. H. (1999). Memory for serial order: A network model of the phonological loop and its timing. Psychological Review, 106(3).
  9. ^ a b Prior, M. R., & Chen, C. S. (1976). Short-term and serial memory in autistic, retarded, and normal children. Journal of Autism and Childhood Schizophrenia, 6(2).
  10. ^ a b Chiba, A., Kesner, R., & Reynolds, A. (1994). Memory for spatial location as a function of temporal lag in rats: Role of hippocampus and medial prefrontal cortex. Behavioral and Neural Biology 61(1).
  11. ^ a b c Chauveau, F., et al. (2009). The hippocampus and prefrontal cortex are differentially involved in serial memory retrieval in non-stress and stress conditions. Neurobiology of Learning and Memory, 91(1).
  12. ^ a b O'Boyle, M. W., & Hellige, J. B. (1982). Hemispheric asymmetry, early visual processes, and serial memory comparison. Brain and Cognition, 1(1).
  13. ^ a b Anderson, J. R., & Matessa, M. (1997). A production system theory of serial memory. Psychological Review, 104(4).
  14. ^ a b Connor, J. M. (1972). Serial and parallel encoding processes in memory and visual search. Journal of Experimental Psychology, 96(2).
  15. ^ Avons, S. E. (1998). Serial report and item recognition of novel visual patterns. British Journal of Psychology, 89(1).
  16. ^ Parmentier, F. B., Tremblay, S., & Jones, D. M. (2004). Exploring the suffix effect in serial visuospatial short-term memory. Psychonomic Bulletin and Review, 11(2).
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