Unexceptional spatial memory in an exceptional memorist.

Rajan Mahadevan evidences an exceptional memory for arrays of digits. We tested whether Rajan's spatial memory was likewise exceptional. Eight control Ss and Rajan were instructed to remember the position and orientation of 48 images of common objects shown either to the left or the right of fixation and facing either left or right. Rajan's accuracy for judging whether the position and orientation of these pictures had changed when they were shown in a different sequence was lower than that of control Ss for both judgments. Rajan's exceptional memory capacity apparently does not extend to spatial relations.     

Memory skills mediating superior memory in a world-class memorist

Laboratory studies have investigated how individuals with normal memory spans attained digit spans over 80 digits after hundreds of hours of practice. Experimental analyses of their memory skills suggested that their attained memory spans were constrained by the encoding time, for the time needed will increase if the length of digit sequences to be memorised becomes longer. These constraints seemed to be violated by a world-class memorist, Feng Wang (FW), who won the World Memory Championship by recalling 300 digits presented at 1 digit/s. In several studies we examined FW’s memory skills underlying his exceptional performance. First FW reproduced his superior memory span of 200 digits under laboratory condition, and we obtained his retrospective reports describing his encoding/retrieval processes (Experiment 1). Further experiments used self-paced memorisation to identify temporal characteristics of encoding of digits in 4-digit clusters (Experiment 2), and explored memory encoding at presentation speeds much faster than 1 digit/s (Experiment 3). FW’s superiority over previous digit span experts is explained by his acquisition of well-known mnemonic techniques and his training that focused on rapid memorisation. His memory performance supports the feasibility of acquiring memory skills for improved working memory based on storage in long-term memory.     

Memorization and recall of very long lists accounted for within the Long-Term Working Memory framework

In a recent paper, Hu, Ericsson, Yang, and Lu (2009) found that an ability to memorize very long lists of digits is not mediated by the same mechanisms as exceptional memory for rapidly presented lists, which has been the traditional focus of laboratory research. Chao Lu is the holder of the Guinness World Record for reciting the most decimal positions of pi, yet he lacks an exceptional memory span for digits. In the first part of this paper we analyzed the reliability and structure of his reported encodings for lists of 300 digits and his application of the story mnemonic. Next, his study and recall times for lists of digits were analyzed to test hypotheses about his detailed encoding processes, and cued-recall performance was used to assess the structure of his encodings. Three experiments were then designed to interfere with the uniqueness of Chao Lu's story encodings, and evidence was found for his remarkable ability to adapt his encoding processes to reduce the interference. Finally, we show how his skills for encoding and recalling long lists can be accounted for within the theoretical framework of Ericsson and Kintsch's (1995) Long-Term Working Memory.     

Memorising Milton's Paradise Lost: A study of a septuagenarian exceptional memoriser

At age 58, JB began memorising Milton's epic poem Paradise Lost. Nine years and thousands of study hours later, he completed this process in 2001 and recalled from memory all 12 books of this 10,565-line poem over a 3-day period. Now 74, JB continues to recite this work. We tested his memory accuracy by cueing his recall with two lines from the beginning or middle of each book and asking JB to recall the next 10 lines. JB is an exceptional memoriser of Milton, both in our laboratory tests in which he did not know the specific tests or procedures in advance, and in our analysis of a videotaped, prepared performance. Consistent with deliberate practice theory, JB achieved this remarkable ability by deeply analysing the poem's structure and meaning over lengthy repetitions. Our findings suggest that exceptional memorisers such as JB are made, not born, and that cognitive expertise can be demonstrated even in later adulthood.     

Visual field differences in the processing of numerical stimuli

Twenty-four right-handed subjects received random presentations of the numbers 1-6 in the form of words, digits, and dot patterns, to the left and right visual fields. Accuracy and reaction time were recorded for an odd-even judgment requiring a manual response. A significant stimulus type of visual field interaction was obtained, with words showing a left-hemisphere advantage and digits and dot patterns showing a right-hemisphere advantage. This pattern supports Coltheart's (1980, Deep dyslexia: A right hemisphere hypothesis, In M. Coltheart, K. Patterson, & J.C. Marshall (Eds.), Deep dyslexia, London: Routledge & Kegan Paul) right hemisphere reading hypothesis, which suggests that the left hemisphere's general advantage in processing linguistic material may be specific to stimuli which involve phonological processing. When phonological processing is not possible (e.g., for arabic digits and other ideographic orthographies), the right hemisphere may have an advantage because of its superior visuospatial processing capabilities.     

One percent ability and ninety-nine percent perspiration: a study of a Japanese memorist

In 1987, Hideaki Tomoyori, a Japanese memorist, set a world record for reciting the first 40,000 digits of pi. The authors report results from a series of tests that give a view of Tomoyori's memory performance compared with that of a control group, matched for age and educational level. He showed very good scores on tasks with digits, such as digit memory span tasks and 5 x 5 number matrix learning, although some of the control participants were nearly as good. In contrast, his performance was not particularly good for learning word lists and story recall. Overall, his performance on the tasks does not suggest that he has superior cognitive abilities. We believe that his extraordinary memory performance in reciting the digits of pi results from his effective use of a combination of digit-syllable transformations and imagery mnemonics developed from extensive practice. These results are consistent with the skilled memory framework.     

Developmental differences in working memory: Where do they come from?

Several models assume that working memory development depends on age-related increases in efficiency and speed of processing. However, age-related increases in the efficiency of the mechanisms that counteract forgetting and restore memory traces may also be important. This hypothesis was tested in three experiments by manipulating both the processing duration within a working memory task and the time available to restore memory traces. Third- and sixth-grade children performed a complex span task in which they maintained series of letters while adding numbers to series of digits. When we equated processing and restoration times between ages, the developmental difference in working memory span was reduced but remained significant. However, this residual difference was eliminated when the time available to reactivate memory traces was tailored to the processing speed of each age group. This indicates that children employ active mechanisms for maintenance and restoration of memory traces that develop with age.     

Memory for symmetry: real or artifact

Subjects recalled nonrandom digit sequences according to either (a) free recall or (b) a serial recall mode in a series of three studies. Sequential structure was varied with specific rules determining higher-order structure of either (a) arithmetic, (b) symmetrical, or (c) haphazard types. In Experiment I, 18 temporal patterns of 12 digits each were presented visually. Although symmetric patterns were easier than the other two pattern types, this superiority was not determined by recall mode. In Experiment II, 6 temporal patterns of 18 digits each were presented visually, with results similar to those of Experiment I. Auditory patterns equivalent to those of Experiment II were presented in Experiment III. In this study, although the free recall mode produced slightly superior recall with symmetrical sequences, this difference was not statistically significant. It was concluded that superior memory for symmetries cannot be wholly accounted for by organizational strategies made possible by a free recall mode.     

Cross‐Linguistic Differences in Digit Memory Span

This study investigated whether the better performance of the Chinese in digit memory span tasks was due only to the shorter pronunciation duration of Chinese digit names, or to enhanced visuospatial sketchpad abilities, or to both. Results of the experiment showed that the Chinese outperformed their Malay counterparts in digit memory span tasks because Chinese digit names had shorter pronunciation durations than Malay digit names and not because the Chinese had better visuospatial sketchpad abilities than the Malays. The results thus support Baddeley's phonological loop hypothesis as an account for cross‐linguistic differences in digit memory spans. Because memory traces are subject to decay and the phonological store is temporally limited, the shorter the pronunciation duration of digit names in a language, the more digits one can rehearse within a limited time period, and therefore the larger is one's short‐term digit span in that language.     

Growth curve models in retrospective memory and prospective memory: the relationship between prediction and performance with task experience

Older adults commonly experience declines in episodic memory that affect their daily lives. The aim was to examine whether the acquired metacognitive awareness that comes with task experience, indexed by meta-retrospective memory (meta-RM)/meta-prospective memory (meta-PM), influences how older adults predict performance on later trials. Participants were 178 community-dwelling older adults. RM performance and predictions were measured using a multi-trial word-list learning task. Predictions and performance for PM were measured using a PM paradigm. Change in RM/PM performance and predictions over the trials/blocks were modelled using latent growth curve analyses. For RM, both predictions and performance increased with task experience. However, for PM, neither performance nor predictions changed with task experience. Hierarchical multiple regressions revealed that metacognitive awareness acquired during the RM and PM tasks influenced how older adults’ modified their predictions of subsequent task performance. Findings are consistent with [Toglia and Kirk’s (2000). Understanding awareness deficits following brain injury. NeuroRehabilitation, 15(1), 57–70] hypothesis that individuals compare ongoing performance to expectations based on metacognitive knowledge, such that a discrepancy between actual and expected performance may influence emergent awareness.     

A cognitive assessment of highly superior autobiographical memory

Highly Superior Autobiographical Memory (HSAM) is characterised as the ability to accurately recall an exceptional number of experiences and their associated dates from events occurring throughout much of one's lifetime. The source of this ability has only begun to be explored. The present study explores whether other enhanced cognitive processes may be critical influences underlying HSAM abilities. We investigated whether enhanced abilities in the domains of verbal fluency, attention/inhibition, executive functioning, mnemonic discrimination, perception, visual working memory, or the processing of and memory for emotional details might contribute critically to HSAM. The results suggest that superior cognitive functioning is an unlikely basis of HSAM, as only modest advantages were found in only a few tests. In addition, we examined HSAM subjects’ memory of the testing episodes. Interestingly, HSAM participants recalled details of their own experiences far better than those experiences that the experimenter shared with them. These findings provide additional evidence that HSAM involves, relatively selectively, recollection of personal, autobiographical material.     

Effects of divided attention in the word-fragment completion task with unique and multiple solutions

A study with 114 young adults investigated the correlations of intelligence factors and working-memory capacity with reaction time (RT) tasks. Within two sets of four-choice RT tasks, stimulus–response compatibility was varied over three levels: compatible, incompatible, and arbitrary mappings. Two satisfactory measurement models for the RTs could be established: A general factor model without constraints on the loadings and a nested model with two correlated factors, distinguishing compatible from arbitrary mappings, with constraints on the loadings. Structural models additionally including factors for working memory and intelligence showed that the nested model with correlated factors is superior in fit. Working-memory capacity and fluid intelligence were correlated strongly with the nested factor for the RT tasks with arbitrary mappings, and less with the general RT factor. The results support the hypothesis that working memory is needed to maintain arbitrary bindings between stimulus representations and response representations, and this could explain the correlation of working-memory capacity with speed in choice RT tasks.     

感觉记忆中含语义对象的视觉表征

感觉记忆能够以特征形式构建对视觉对象表面信息的表征, 然而对于具有重要意义的潜在抽象信息, 尚未有研究考察其是否影响感觉记忆的视觉表征。结合掩蔽技术与部分报告法范式考察了感觉记忆的视觉表征中是否包含语义信息。以阿拉伯数字作为目标, 实验1与实验2分别采用正立与倒置的汉字大写数字作为掩蔽刺激, 比较其与白噪音刺激的掩蔽效应。结果显示, 汉字大写数字的掩蔽效应均强于白噪音刺激, 且正立汉字大写数字的掩蔽效果较倒置汉字大写数字更强。实验3采用汉字大写数字与汉字常用字分别作为掩蔽刺激, 结果显示汉字大写数字的掩蔽效果强于汉字常用字。上述结果显示, 刺激间的语义相似性带来了视觉表征冲突, 表明感觉记忆的视觉表征中包含了刺激的语义信息。     

Mixed- versus strong right-handedness is associated with biases towards "remember" versus "know" judgements in recognition memory: role of interhemispheric interaction

Growing evidence supports the hypothesis that episodic versus semantic memories rely primarily on interhemispheric versus intrahemispheric processing, respectively. For example, a recent study found that individuals with presumed greater interhemispheric interaction were superior in episodic recall but inferior at semantic word fragment completion; however, tests of recognition memory yielded no group differences. Interestingly, recognition memory can be based on either explicitly remembering a stimulus or implicitly knowing that a stimulus had been presented. The current experiments administered recognition memory tests to strongly versus mixed handed participants who judged for each recognised item whether their response was based on remembering (episodic memory) or knowing (semantic memory) (Tulving, 1983). Results indicate that strong versus mixed handers are biased towards basing recognition responses on judgements of knowing versus remembering, respectively. As strong versus mixed handedness is associated with greater versus lesser interhemispheric processing, the results support the original hypothesis.     

The memory of two great mental calculators: Charcot and Binet's neglected 1893 experiments

French neurologist Jean Martin Charcot (1825-1893) and French psychologist Alfred Binet (1857-1911) are almost unknown as investigators who conducted original and fascinating studies in the area of memory. In a series of 1893 experiments, they compared the performance of two expert mental calculators, Jacques Inaudi and Périclès Diamandi, in tasks that consisted of recalling digits. Inspired by Ribot's psychological work (1881), they believed in the existence of not one type of memory but several partial, special, and local memories, each devoted to a particular domain. In all arithmetical prodigies, memory for digits is abnormally developed compared with other memories. Inaudi was considered to be an auditory memory-based mental calculator; when memorizing digits, he did not rely onthe appearance of the items or create visual imagery of any kind. Rather, he remembered digits principally by their sounds. Inaudi's methods of calculation and memorization were original and different from those used by Diamandi, who was a typical visual memory-based mental calculator. The experiments presented in the 1893 article were among the first scientific demonstrations of the importance to psychology of studying different types of memory. The present work gives a translation of this pioneering experimental article on expert calculators by Charcot and Binet, instructive for the comprehension of normal memory.     

Repetition priming in simple addition depends on surface form and typicality

Repetition priming and recognition memory for numbers were measured in four experiments using single-digit addition. Results of the first two experiments indicate that when numbers were presented as number words and dot configurations, preexposure of the same problem in the same notation produced greater reaction-time benefit than did preexposure of the same problem in Arabic-digit notation. In contrast, when numbers were presented as Arabic digits, preexposure of the same problem in Arabic digit, number word, and dot notation produced the same amount of priming. In the third experiment, priming was shown to be greatest, for all three notations, when the task performed on preexposure trials (addition or multiplication) matched the task performed on repetition trials (addition). Results of the fourth experiment, measuring recognition memory, were comparable to the priming results in the sense that memory was superior when notation matched across repetitions if the test involved number words and dot configurations but not Arabic digits. These data are interpreted in terms of models of numerical cognition, and they support the hypothesis that the influence of surface form on repetition priming depends on the typicality of the input for the task.     

Micro-position effects in visual short term memory

Short-term memory for visually presented eight-digit numbers was tested in a forced recall, read-and-dial task. The digits were presented non-grouped or grouped in 2+2+2+2 or 2+3+3 digit formats. Spatial grouping enhanced memory performance and produced local discontinuities in the serial position curves related to grouping format. These micro-position effects are explained in terms of the relative spatial distinctiveness of individual digits.     

The Prospective and Retrospective Memory Questionnaire (PRMQ): factorial structure, relations to global subjective memory ratings, and Swedish norms

The factorial structure of the Prospective and Retrospective Memory Questionnaire (PRMQ; Smith et al., 2000) was examined in a Swedish population based sample (N= 540, age range; 35-90 years). Concurrent validity was assessed by relating PRMQ to global ratings of memory. Confirmatory factor analyses of the PRMQ items indicated a superior fit of a three-factor model, with prospective and retrospective memory as orthogonal factors and episodic memory as a common factor. Furthermore, the PRMQ scales correlated with the global ratings of memory, suggesting that each rating contributed with unique variance in predicting PRMQ scores. Given differences in levels of complaints as compared with prior research (Crawford et al., 2003) norms for the Swedish version are provided. In conclusion, the present findings extend earlier work by providing additional support for the construct and concurrent validity of the PRMQ scales.     

Memory for pitch in congenital amusia: Beyond a fine-grained pitch discrimination problem

Congenital amusia is a disorder that affects the perception and production of music. While amusia has been associated with deficits in pitch discrimination, several reports suggest that memory deficits also play a role. The present study investigated short-term memory span for pitch-based and verbal information in 14 individuals with amusia and matched controls. Analogous adaptive-tracking procedures were used to generate tone and digit spans using stimuli that exceeded psychophysically measured pitch perception thresholds. Individuals with amusia had significantly smaller tone spans, whereas their digits spans were a similar size to those of controls. An automated operation span task was used to determine working memory capacity. Working memory deficits were seen in only a small subgroup of individuals with amusia. These findings support the existence of a pitch-specific component within short-term memory and suggest that congenital amusia is more than a disorder of fine-grained pitch discrimination.     

成人短时记忆发展的实验研究

以数字、图形和颜色为实验材料,测量了青年和老年被试在记忆广度和斯腾伯格任务中的成绩。结果表明随着年龄的增大,三种材料的记忆广度都有显著的下降,记忆的搜索速度也减慢;发现在老年期不同材料的记忆广度与搜索速度也存在反比例关系。作者认为这一结果对短时记忆容量发展研究具有重要意义并进行了进一步的讨论。