Working memory for movement patterns: a direct comparison of memory spans for body and hand movements in dual-task situations

In this experiment, 36 participants engaged in one of three span tasks; digit span, body movement span, or hand movement span task, in which they were asked to remember visually presented sequences of digits, whole body movement patterns, or hand movement patterns, respectively. As in a standard memory span procedure, the items within each sequence were recalled in order. Participants were presented with increasingly longer sequences of the items, and span score was defined as the number of items in the longest sequence a participant could recall perfectly. The span tasks were tested under three concurrent task conditions; no concurrent task control, concurrent articulation task, and concurrent body-related movement task. The concurrent movement task interfered with performance on both body movement and hand movement span tasks, but not on the digit span task, while the concurrent articulation task interfered with performance on all of the three span tasks. It is suggested that memory for movement patterns, which is involved in the body and band movement spans, would be mediated by a common motor-processing system.     

Verbal and nonverbal short‐term memory in patients with Alzheimer's disease and in healthy elderly subjects

Short‐term memory (STM) deteriorates with the progression of Alzheimer's disease (AD). The purpose of the present study was to characterize this decline by examining component processes of STM. Accordingly, AD patients whose dementia ranged from mild to severe and healthy, age‐matched subjects received the Brown‐Peterson distractor task, in which class of material (verbal and nonverbal), number of memoranda (one, two, and three), and agent of forgetting (time and distraction) were manipulated. Healthy elderly subjects showed the expected pattern of performance: When distraction was present, forgetting was greater with longer retention intervals and larger memory loads; when distraction was absent, recall was perfect. AD patients showed significant forgetting at shorter intervals and with smaller memory loads than healthy elderly subjects when distraction was present; without distraction, AD patients' recall of nonverbal (but not verbal) material was impaired, which may be attributable to the greater difficulty of the nonverbal task over the verbal one and to a diminished rehearsal capacity of AD patients for nonverbal material. Data from individual patients suggest that the verbal and nonverbal systems can deteriorate independently.     

Morphological processing with deficient phonological short-term memory

This paper investigates the processing of Hebrew derivational morphology in an individual (S.E.) with deficient phonological short-term memory. In comparison to 10 age- and education-matched men, S.E. was impaired on digit span tasks and demonstrated no recency effect in word list recall. S.E. had low word retention span, but he exhibited phonological similarity and word length effects. His ability to make lexical decisions was intact. In a paired-associate test S.E. successfully learned semantically and morphologically related pairs but not phonologically related pairs, and his learning of nonwords was facilitated by the presence of Hebrew consonant roots. Semantic and morphological similarity enhanced immediate word recall. Results show that S.E. is capable of conducting morphological decomposition of Hebrew-derived words despite his phonological deficit, suggesting that transient maintenance of morphological constituents is independent of temporary storage and rehearsal of phonological codes, and that each is processed separately within short-term memory.     

Morphological processing with deficient phonological short-term memory

This paper investigates the processing of Hebrew derivational morphology in an individual (S.E.) with deficient phonological short-term memory. In comparison to 10 age- and education-matched men, S.E. was impaired on digit span tasks and demonstrated no recency effect in word list recall. S.E. had low word retention span, but he exhibited phonological similarity and word length effects. His ability to make lexical decisions was intact. In a paired-associate test S.E. successfully learned semantically and morphologically related pairs but not phonologically related pairs, and his learning of nonwords was facilitated by the presence of Hebrew consonant roots. Semantic and morphological similarity enhanced immediate word recall. Results show that S.E. is capable of conducting morphological decomposition of Hebrew-derived words despite his phonological deficit, suggesting that transient maintenance of morphological constituents is independent of temporary storage and rehearsal of phonological codes, and that each is processed separately within short-term memory.     

Articulation and verbal short-term memory: Evidence from anarthria

The role of articulation in verbal short-term memory was investigated in two patients suffering from a selective and total impairment of overt articulation. Case GF was totally speechless due to a ventral pontine lesion and case MDC due to bilateral anterior opercular softenings. Both patients had normal auditory comprehension, a digit span performance within the normal range, and displayed the standard effect of phonological similarity in immediate memory performance with auditory material. This pattern of results suggests that a total impairment of overt articulation, occurring in adult age, does not disrupt the function of the phonological short-term store component of working memory. These conclusions are consistent with the view that a phonological nonarticulatory input short-term storage system is a main functional component involved in auditory span performance. Finally, while GF's phonological processing of visual material was unaffected, in MDC's case a defective phonological recoding of visual information was shown. This differential pattern of impairment suggests that a defective function of the phonological recoding component may prevent access by visually presented material to an unimpaired rehearsal process. A model comprising an input phonological short-term store, an articulatory rehearsal loop, and a phonological recoding process component is discussed.     

Digit repetition in brain-damaged adults: clinical and theoretical implications

Digit repetition was investigated in samples of unilaterally (N = 87) and bilaterally (N = 75) brain-damaged adults. The study was designed to investigate the hemispheric and neuropsychological factors that underlie performance on these two dissimilar tasks. Digit repetition was disproportionately depressed in such patients, especially those with left hemisphere lesions. The incidence of individually impaired digit repetition performance, especially of digits backward, was significantly higher than in normals, again particularly within the left hemisphere sample. However, impaired digit repetition was not invariably associated with brain dysfunction. The data suggest, but do not confirm, a differential function hypothesis, as well as a unilateral hemispheric hypothesis that underlies the ability to repeat forward and backward digits; this finding is consistent with some previous literature. Group performance showed considerable overlap, which limited the possibility of demonstrating a double dissociation between digits forward and verbal measures, and digits backward and nonverbal factors. Digit repetition in brain-damaged patients appears to have some theoretical value, but limited clinical utility.     

Education, Age, and the Brown-Peterson Technique

In this article, we discuss the effects of education level and age on short-term memory. The performance of young and elderly persons was compared on an adapted version of the Brown-Peterson procedure. Participants were asked to report consonant trigrams, after variable time periods, during which they performed a mental addition task or an articulation task. A control condition consisted of a no-interference task. Both age groups were divided according to individual educational level (greater or less than the median number of school years in each age group). The results revealed a significant effect of education. Moreover, the education effect interacted with the task: participants with less education were more impaired in mental addition than in articulation. However, neither the age effect nor the interactions involving age reached significance. These results indicate that education, to a greater extent than age, should be considered a determining factor of performance when interpolated tasks of high demand are used with the Brown-Peterson procedure.     

Education,Age, and the Brown-Peterson Technique

In this article, we discuss the effects of education level and age on short-term memory. The performance of young and elderly persons was compared on an adapted version of the Brown-Peterson procedure. Participants were asked to report consonant trigrams, after variable time periods, during which they performed a mental addition task or an articulation task. A control condition consisted of a no-interference task. Both age groups were divided according to individual educational level (greater or less than the median number of school years in each age group). The results revealed a significant effect of education. Moreover, the education effect interacted with the task: participants with less education were more impaired in mental addition than in articulation. However, neither the age effect nor the interactions involving age reached significance. These results indicate that education, to a greater extent than age, should be considered a determining factor of performance when interpolated tasks of high demand are used with the Brown-Peterson procedure.     

Pentadactyl manus of the Metoposaurus krasiejowensis from the Late Triassic of Poland,the first record of pentadactyly among Temnospondyli

Temnospondyli are commonly believed to have possessed four digits in the manus and five in the pes. However, actual finds of articulated autopodia are extremely rare. Therefore, an articulated, slightly incomplete forelimb skeleton with preserved manus of Metoposaurus krasiejowensis from the Late Triassic of Poland is important in providing new details about the structure and ossification sequence in the temnospondyl limb. The most important observation is the presence of five metacarpals in this specimen. This allows reconstructing the manus as pentadactyl. The number of phalanges and the distribution of distal articulation facets allow reconstruction of the digit formula as (2?)‐3‐3‐(3?)‐(2?). The well‐developed fifth digit suggests that the Metoposaurus manus shows a unique ossification sequence: the reduction or late ossification of the first digit conforms to the amniote‐frog pattern, and the early development of the second and third digit makes M etoposaurus similar to salamanders. Based on the distribution of pentadactyly vs. tetradactyly in the temnospondyl manus, the number of digits was not phylogenetically constrained in temnospondyls, similar to today''s amphibians.     

Is the thumb a fifth finger? A study of digit interaction during force production tasks

We studied indices of digit interaction in single- and multi-digit maximal voluntary contraction (MVC) tests when the thumb acted either in parallel or in opposition to the fingers. The peak force produced by the thumb was much higher when the thumb acted in opposition to the fingers and its share of the total force in the five-digit MVC test increased dramatically. The fingers showed relatively similar peak forces and unchanged sharing patterns in the four-finger MVC task when the thumb acted in parallel and in opposition to the fingers. Enslaving during one-digit tasks showed relatively mild differences between the two conditions, while the differences became large when enslaving was quantified for multi-digit tasks. Force deficit was pronounced when the thumb acted in parallel to the fingers; it showed a monotonic increase with the number of explicitly involved digits up to four digits and then a drop when all five digits were involved. Force deficit all but disappeared when the thumb acted in opposition to the fingers. However, for both thumb positions, indices of digit interaction were similar for groups of digits that did or did not include the thumb. These results suggest that, given a certain hand configuration, the central nervous system treats the thumb as a fifth finger. They provide strong support for the hypothesis that indices of digit interaction reflect neural factors, not the peripheral design of the hand. An earlier formal model was able to account for the data when the thumb acted in parallel to the fingers. However, it failed for the data with the thumb acting in opposition to the fingers.     

Attentional stages of information processing during a continuous performance test: A startle modification analysis

This study of 31 college students employed the startle eye-blink modification (SEM) technique to index both early and later stages of attentional processing during a memory-load version of the Continuous Performance Test (CPT). Participants viewed a series of digits and pressed a button after the digit 7 of each 3-7 sequence. A startling noise burst was presented either 120 or 1,200 ms following three preselected prepulses: target (3), nontarget (non-3 and non-7 digits), or target plus distractor (3 and simultaneous tone distractor). Greater startle inhibition occurred 120 ms following target and target-plus-distractor prepulses compared with nontargets, indicating early selective attention. No difference was observed between SEM during target and target-plus-distractor prepulses, suggesting the distractor was effectively ignored. At 1,200 ms, the three prepulse types produced nondifferential inhibition, suggesting that modality-specific selective attention occurs in anticipation of the presentation of the next CPT prepulse. These findings indicate that SEM distinguishes between different early selective attention and later anticipatory attention subprocesses underlying the CPT.     

Shared versus separate processes for letter and digit identification

Letters and digits, although similar in many respects, also differ in potentially significant ways. Most importantly, letters are elements of an alphabetic writing system, whereas digits are logographs. In this article, we explore whether letters and digits are identified by a single character identification process that makes no fundamental distinction between the two types of characters, or whether instead letter and digit identification processes diverge at least in some respects. We present evidence from an acquired dyslexic patient, L.H.D., who is impaired in both letter and digit identification. Working within a theoretical framework specifying the levels of representation implicated in letter identification, we systematically compare L.H.D.'s letter and digit processing. The results provide evidence that letter and digit identification implicate the same levels of representation, and further that L.H.D.'s identification errors for both letters and digits arise at the same point in processing. On the basis of these results, we argue for a shared process that mediates identification of both letters and digits. Finally, we discuss relevant previous results in light of this conclusion.     

Digit repetition in learning-disabled children

Investigated digit repetition performance in learning-disabled children in an effort to assess its clinical and theoretical significane. Clinically, learning disabled children were found to demonstrate a higher than expected incidence of large verbal-performance discrepancies, although mean overall digit repetition performance did not differ appreciably form that expected on the basis of intelligence (N = 100). Children with large discrepancies did not differ from those with no such discrepancies when compared no a variety of psychometric and neurobehavioral factors. Theoretically, a hemispheric specialization model and a neuropsychology function model have been proposed to underie performance on the two somewhat different digit repetition tasks (forward and backward repetition). Some support was found for the neuropsychological function model, with significant correlations obtained between digits forward and a measure of languge function and between digits backward and a test of visual constructional ability. Stronger evidence that could have been provided by double dissociation of correlational findings was limited by a smaller, but significant, correlation between digits forward and Bender Gestalt errors. However, the results are consistent with previous research in suggesting that digit repetition cna an avenue to the study of brain-behavior relationships.     

Task-specific modulation of multi-digit forces to object texture

During multi-digit grasping both local and non-local digit force responses occur in response to changes in texture at selected digits depending on the grasp configuration. However, the extent to which the specific patterns of force distribution depend on the requirement to hold the object against gravity remains to be determined. In the present study, we examined whether grasp force sharing patterns are invariant when the constraint of maintaining the object orientation vertical against gravity is removed. We used changes in object texture to elicit force changes at single digits during two grasping tasks with different behavioral contexts. One task entailed holding an object against gravity (object hold [OH]). A second (force production [FP]) task consisted of generating lifting forces on an object clamped to the tabletop that were matched to those used during OH. Unlike OH, the FP task lacks the behavioral consequences associated with erroneous sharing of normal and tangential digit forces, e.g., object tilt. Ten subjects lifted and simulated lifting an instrumented object measuring grasping normal and vertical tangential forces at all five digits when the textures were uniformly high-friction sandpaper or low-friction rayon and when one digit contacted a different frictional texture than the other four digits. We found that in both tasks texture changes at individual digits elicited force changes at that digit as well as other digits. However, the specific pattern of force distribution changes differed during OH compared to FP. While subjects modulate the normal and tangential digit forces to different degrees depending on object texture and the grasping task, they ignore the requirement of moment equilibrium when this has no consequences on object orientation (FP task). These findings indicate that multi-digit force responses to texture revealed by previous studies are not obligatory and suggest that the behavioral context of a task should be considered when inferring general principles of multi-digit force coordination.     

Short-term synchronization between motor units in different functional subdivisions of the human flexor digitorum profundus muscle

The ability to independently move the digits is limited by peripheral as well as central factors. A central limitation to independent finger movements might arise from the inability of the human nervous system to activate motor units (MUs) that exert force on one finger without also activating MUs that exert force on adjacent fingers. Short-term synchronization between MU pairs is thought to be the result of the two motoneurons receiving common input from last-order neuronal projections. The human flexor digitorum profundus (FDP) muscle contains four subdivisions, one for each of the fingers. We hypothesized that the distribution of MU synchrony within and between subdivisions of FDP might parallel the ability to selectively activate different functional subdivisions within FDP, and the ability to flex one digit independently of another. We found that the degree of MU synchrony indeed was not uniform among the different functional subdivisions of FDP; MUs acting on ulnar digits (d5, d4) were more synchronized than MUs acting on radial digits (d2, d3). Furthermore, synchrony was observed between MU pairs where each unit acted on a different digit and was highest when both units of a pair acted on the least-independent digits (d4, d5). This indicates that the CNS does not exert completely independent control over the different functional subdivisions of FDP. The strength of synchrony appears related to the inability to produce completely independent forces or movements with the digits. These observations reflect widespread divergence of last-order inputs within the FDP motoneuron pool, and we suggest that the organization of the CNS drive to this muscle contributes to the limited ability of humans to flex one digit in isolation from other digits.     

A critical re-evaluation of the association between 2D:4D ratios and fluctuating asymmetry in humans

Background: Both asymmetry and the second and fourth digit ratio (2D:4D) relate to various aspects of human life history. Higher asymmetry with extreme 2D:4D ratios have suggested a link between both processes, indicating that early development determines levels of developmental instability. However, most observed associations may be biased because combinations of the digit lengths are used as both dependent and independent variables.

Aim: The present study explored the usefulness of asymmetry in digits 2 and 4 to study this association.

Subjects and methods: A combination of literature review, a small simulation study, and a study of 2D:4D ratios and asymmetry in a total of 100 young males and females is presented.

Results: Using asymmetry in digits 2 and 4 results in bias and increased type I error rates, leading to stronger associations between asymmetry and 2D:4D ratios. In spite of low sample sizes, significant associations between asymmetry measured in hands and face and 2D:4D ratios were detected for asymmetries in digits 2 and 4 only.

Conclusions: Using asymmetry in digits 2 and/or 4 causes bias. Excluding such results, there is currently little evidence of any association between asymmetry and digit ratios. Future studies should carefully select traits to investigate these correlations further.     

Consequences of unremitting middle-ear disease in early life. Otologic, audiologic, and developmental findings in children with cleft palate

To learn whether chronic otitis media with effusion during early life has lasting otologic, audiologic, or developmental consequences, we evaluated 24 closely matched pairs of children with repaired palatal clefts whose treatment had been equivalent except with regard to persistent otitis media during early life. One group had undergone early (mean age, 3.0 months) myringotomy with placement of tympanostomy tubes, followed by assiduous monitoring and an aggressive treatment program to maintain ventilation in the middle ear. The other group had undergone initial myringotomy later (mean age, 30.8 months) or not at all (two subjects) and presumably had had continuous middle-ear effusion throughout most or all of the first few years of life. Eardrum scarring was equal in both groups. Hearing acuity and consonant articulation were impaired in both groups, but hearing acuity was less impaired (P = 0.05 to 0.10) and consonant articulation significantly less impaired (P = 0.03) in the group undergoing early myringotomy. Mean verbal, performance, and full-scale IQs and scores on psychosocial indexes were normal in both groups and did not differ significantly between the groups. These findings support the hypothesis that early, longstanding otitis media may result in impairment of hearing and of speech, but they do not support the hypothesis that cognitive, language, and psychosocial development are adversely affected.     

Automated method for detecting and reading seven-segment digits from images of blood glucose metres and blood pressure monitors

Abstract

There is an increasing need for fast and accurate transfer of readings from blood glucose metres and blood pressure monitors to a smartphone mHealth application, without a dependency on Bluetooth technology. Most of the medical devices recommended for home monitoring use a seven-segment display to show the recorded measurement to the patient. We aimed to achieve accurate detection and reading of the seven-segment digits displayed on these medical devices using an image taken in a realistic scenario by a smartphone camera. A synthetic dataset of seven-segment digits was developed in order to train and test a digit classifier. A dataset containing realistic images of blood glucose metres and blood pressure monitors using a variety of smartphone cameras was also created. The digit classifier was evaluated on a dataset of seven-segment digits manually extracted from the medical device images. These datasets along with the code for its development have been made public. The developed algorithm first preprocessed the input image using retinex with two bilateral filters and adaptive histogram equalisation. Subsequently, the digit segments were automatically located within the image by two techniques operating in parallel: Maximally Stable Extremal Regions (MSER) and connected components of a binarised image. A filtering and clustering algorithm was then designed to combine digit segments to form seven-segment digits. The resulting digits were classified using a Histogram of Orientated Gradients (HOG) feature set and a neural network trained on the synthetic digits. The model achieved 93% accuracy on digits found on the medical devices. The digit location algorithm achieved a F1 score of 0.87 and 0.80 on images of blood glucose metres and blood pressure monitors respectively. Very few assumptions were made of the locations of the digits on the devices so that the proposed algorithm can be easily implemented on new devices.     

Prehension is really reaching and grasping

Prehension has traditionally been seen as the act of coordinated reaching and grasping. However, recently, Smeets and Brenner (in Motor Control 3:237-271, 1999) proposed that we might just as well look at prehension as the combination of two independently moving digits. The hand aperture that has featured prominently in many studies on prehension, according to Smeets and Brenner's "double-pointing hypothesis", is really an emergent property related to the time course of the positions of the two digits moving to their respective end points. We tested this double-pointing hypothesis by perturbing the end position of one of the digits while leaving the end position of the opposing digit unchanged. To this end, we had participants reach for and grasp a metallic object of which the side surfaces could be made to slide in and out. We administered the perturbation right after movement initiation. On several occasions, after perturbing the end position of one digit, we found effects also on the kinematics of the opposing digit. These findings are in conflict with Smeets and Brenner's double-pointing hypothesis.     

Independent movements of the digits in grasping

Reaching out for an object is often considered to consist of the control of two components: transporting the hand to the object's position, and scaling the grip to the object's size. We recently proposed an alternative view. According to this view, grasping consists of controlling the digits, not the hypothetical transport and grip. This alternative view assumes that the opening of the hand emerges from the trajectories of the digits. We therefore studied the movements of the digits in grasping. We asked subjects to grasp disks (diameters ranging from 5 to 8 cm) at marked positions with two digits. The positions were at opposite sides of the disk, at the same distance from the starting position, so that the orientation of the surface was the same for both digits. The subjects grasped the disks either with the index finger and thumb of the dominant hand, with the same digits of the non-dominant hand, or bimanually with both index fingers. Our predictions are: that the well-known relation between object size and grip aperture holds for each digit; that the same relation holds if the object is grasped with two hands instead of with the thumb and finger of one hand; that maximum deviation, variability and duration of the digit movements are related; and that variations in the timing of the maximum deviation of one digit are independent of those in the other digit. In accordance with our predictions, we found that the maximum deviation of both digits increased with 0.75 times the object radius, independent of the hand(s) used. The movements of the thumb were more variable than those of the index finger, which was reflected by a larger deviation earlier in the movement. The timing of the maximum deviation of the two digits was independent. These results on the digits' movements are consistent with our view that grasping can be understood as the largely independent movements of the digits. The results are not in conflict with the hypothesis that the grip is controlled during grasping, but can only be explained by extending that hypothesis post hoc. Electronic Publication