Manipulatory Skills Research Articles

Comparative anatomy of the Sapajus sp. (bearded capuchin) hand with comments on tool use in a parallel evolution with the hominid pathway.

Introduction: Bearded capuchins display a wide variety of manipulatory skills and make routine use of tools in both captivity and the wild. The efficient handling of objects in this genus has led several investigators to assume near-human thumb movements, despite a lack of anatomical studies. Methods: Here, we performed an anatomical analysis of muscles and bones in the capuchin hand. Sapajus morphological traits were quantitatively compared with those of humans, chimpanzees, gorillas, and baboons. Results: The comparative analysis indicated that the Sapajus hand is more similar to that of baboons and least similar to that of humans according to the muscles, bones, and three-dimensional data. Furthermore, these findings suggest that bearded capuchins lack true thumb opponency. Regarding manipulatory skills, they display rather primitive hand traits, with limited resources for precision grasping using the opponens pollicis. Discussion: These findings suggest that bearded capuchins' complex use of tools depends more heavily on their high cognitive abilities than on a versatile hand apparatus. These findings offer crucial insights into the evolution of primate cognition.

Adaptive bill morphology for enhanced tool manipulation in New Caledonian crows.

Early increased sophistication of human tools is thought to be underpinned by adaptive morphology for efficient tool manipulation. Such adaptive specialisation is unknown in nonhuman primates but may have evolved in the New Caledonian crow, which has sophisticated tool manufacture. The straightness of its bill, for example, may be adaptive for enhanced visually-directed use of tools. Here, we examine in detail the shape and internal structure of the New Caledonian crow’s bill using Principal Components Analysis and Computed Tomography within a comparative framework. We found that the bill has a combination of interrelated shape and structural features unique within Corvus, and possibly birds generally. The upper mandible is relatively deep and short with a straight cutting edge, and the lower mandible is strengthened and upturned. These novel combined attributes would be functional for (i) counteracting the unique loading patterns acting on the bill when manipulating tools, (ii) a strong precision grip to hold tools securely, and (iii) enhanced visually-guided tool use. Our findings indicate that the New Caledonian crow’s innovative bill has been adapted for tool manipulation to at least some degree. Early increased sophistication of tools may require the co-evolution of morphology that provides improved manipulatory skills.

Anatomical analysis of thumb opponency movement in the capuchin monkey (Sapajus sp).

Capuchin monkeys present a wide variety of manipulatory skills and make routine use of tools both in captivity and in the wild. Efficient handling of objects in this genus has led several investigators to assume near-human thumb movements despite the lack of anatomical studies. Here we perform an anatomical analysis of muscles and bones in the capuchin hand. Trapezo-metacarpal joint surfaces observed in capuchins indicate that medial rotation of metacarpal I is either absent or very limited. Overall, bone structural arrangement and thumb position relative to the other digits and the hand’s palm suggest that capuchins are unable to perform any kind of thumb opponency, but rather a ‘lateral pinch’ movement. Although the capuchin hand apparatus bears other features necessary for complex tool use, the lack thumb opposition movements suggests that a developed cognitive and motor nervous system may be even more important for high manipulatory skills than traditionally held.

Laterality in tool manufacture by crows

Neural processing and not ecological factors may influence 'handedness' in these birds. New Caledonian crows (Fig. 1) fashion tapered tools from either the left or the right edge of the long narrow leaves of pandanus trees or screw pines1,2, which they use to extract invertebrates in rainforest vegetation2. Although right-handedness is thought to be uniquely human3, we show here that crows from different localities display a widespread laterality in making their tools, indicating that this behaviour is unlikely to be attributable to local social traditions or ecological factors. To our knowledge, this is the first demonstration of species-level laterality in manipulatory skills outside humans.

Development of manipulatory skills and the deployment of attention

Two independent tasks, object manipulation and auditory-visual matching, were used to examine the relationship between developing manual action skills and attention to intermodal object properties in 3.5- and 5.5-month-olds. Although handling skills improved with age, with older infants demonstrating more varied manipulation, there were no age differences for the matching task. When grouped by handling skills, a significant interaction between skill and event type was found for the two age groups combined and for 5.5-month-olds alone. Auditory-visual matching of social events did not vary with handling skills, whereas auditory-visualmatching of object events did. Infants at higher skill levels responded similarly to social and object events, whereas less skilled infants' matching preferences were weaker for object events. These findings indicate that infants increase their attention to auditory and visual properties of objects as this information becomes useful for guiding new actions. This effect is independent of age due to considerable individual variability in the development of object handling skills.

An examination of the intramodal and intermodal behavioral consequences of long‐term vibrissae removal in rats

An assessment was made of the effects of long-term tactile restriction by bilateral removal of the mystacial vibrissae from an early age on the subsequent somatosensory capacities of rats (i.e., the intramodal consequences) as well as its effects on visual and spatial capacities (i.e., the intermodal consequences). Rearing environment (enriched vs. normal) and method of vibrissae removal (cauterization of follicles vs. plucking) were examined to determine specific factors that m might influence the effect of vibrissae removal. Early, long-term tactile restriction had significant intramodal and intermodal consequences. Dewhiskered rats showed attenuated orientation to tactile stimuli presented to their mystacial pads and enriched-reared rats whose vibrissae follicles had been cauterized showed increased orientation to visual stimuli. Manipulation of early somatosensory signals had no impact on the development of certain spatial and precise manipulatory skills. These data provide limited evidence for theories of modality interdependence and yield basic information concerning the role of the mystacial vibrissae in the behavior of the rat.

Functional specialization in the lower and upper visual fields in humans: Its ecological origins and neurophysiological implications

AbstractFunctional specialization in the lower and upper visual fields in humans is analyzed in relation to the origins of the primate visual system. Processing differences between the vertical hemifields are related to the distinction betweennear(peripersonal) andfar(extrapersonal) space, which are biased toward the lower and upper visual fields, respectively.Nonlinear/globalprocessing is required in the lower visual field in order to pergeive the optically degraded and diplopic images in near vision, whereas objects in far vision are searched for and recognized primarily usinglinear/localperceptual mechanisms. The functional differences between near and far visual space are correlated with their disproportionate representations in thedorsalandventraldivisions of visual association cortex, respectively, and in themagnocellularandparvocellularpathways that project to them. Advances in far visual capabilities and forelimb manipulatory skills may have led to a significant enhancement of these functional specializations.

AUDIOVISUAL 2

Audio‐visual aids begin, as all good followers of Edward Short will tell you, with talk, chalk and blackboard; and should never be allowed to end in a mass of blurting, blinking machinery. Taking in an array of sound arguments for not dehumanizing education, the traditional teacher attitude is, at base, the reflex of a profession bewildered by the mechanical tools which the commercial world seems determined to foist upon it. Machines often demand quite simple manipulatory skills for which teachers aren't trained, but more pertinently they suggest ordered, efficient teaching methods — a combination which leads to fewer, better trained teachers. It is not the A/V aids, however, which are the crux of the matter — the advantages of providing a more varied learning environment are largely accepted.

Age and experience in chimpanzee nest building.

Ten captive-born chimpanzee adults (age range 11-30 yr.; M, 21) who had failed to produce nests in repeated individual tests were selected for training. Five were caged adjacent to and five were caged with chimpanzees who regularly constructed nests. All were supplied with pine straw, burlap, newspaper, hose lengths, rope, etc. Fresh materials were provided whenever possible (a median of 25 times) during July through November. Each time marerials were provided they were allowed to remain in the cages for several days. Whereas most of the wild-born animals constructed a nest each night, none of the captive-born chimpanzees ever produced a nest, despite frequent manipulation of materials and contacts with nests produced by cagemates. Tested individually, the captive-born animals still failed to construct nests whereas six wild-born animals (age range 15-40 yr.; M, 30) caged in pairs all continued to build nests. Competition for materials therefore did not seem to be a factor. Five 3-yr.-old wild-born chimpanzees were tested individually and in pairs for three days with similar nesting materials. Exact age at capture was unknown but all were acquired at about 1 yr. of age. Three of these five produced nests which laboratory staff members could identify from photographs. It is, therefore, suggested that given suitable opportunities and examples chimpanzees learn to construct nests before the age of two. Without this early experience, adult chimpanzees, with all the required manipulatory skills and considerable interest in both the materials and nests produced by cagemaces, may require extensive training to acquire the requisite pattern of responses.

An Evaluation of the Schiotz Sklar Corneal Tonometer used on the Sclera*

SUMMARY This study on 132 randomly selected human eyes has shown that no significant differences would occur if intra-ocular tension measurements are taken on a sitting patient in the head-back position as compared to similar measurements taken on the same patient in the reclined position. Therefore the test can be optometrically applied as described without introducing any appreciable variable. Secondly, it has been shown in this study on 240 randomly selected eyes that the use of the Schiotz Corneal Tonometer, when applied properly to the sclera, will yield similar information to that obtained when it is applied to the anaesthetised cornea, and it is therefore recommended that such instrumentation be utilised by optometric practitioners after they have acquired the necessary manipulatory skills and orientation required for the proper clinical application of this procedure. The study has also included a measurement of 41 known glaucomatous eyes, as indicated in Figure 1, and it is noted that in every case, a positive glaucomatous reading where present, has been yielded in both methods of instrumentation. It is further noted that the increment of differences measured on the cornea as compared LO the sclera on this glaucomatous population did not differ from the measured increment of differences yielded on the total sample population. Further research on a larger glaucomatous population is desired and future efforts should be directed in this area. A number of new areas of investigation now seems fruitful. Realising that any corneal applied instrumentation still may produce some subjective undesirable responses on the part of an unanaesthetised patient, it would be interesting to compare the measurements yielded by the MacKay-Marg Electronic Tonometer applied to the unanaesthetised cornea compared to the measurements obtained if the same instrument probe were applied to one or more suitably selected scleral positions. In conjunction with this study, it would also be desirable to concurrently measure on the same eyes the Schiotz scleral tension as well as the Wolfe scleral tension. With these four measurements, it would be possible to have a circular comparison of the presently available optometric methods (if evaluating intra-ocular tension. This would produce a comparison of MacKay-Marg Electronic Tonometer measurements corneally as compared to scleral. Schiotz sclerdl findings could then be compared to MacKay-Marg scleral and corneal findings and Wolfe scleral findings could be compared to Schiotz scleral findings. Such comparison would yield levels of correlation between these forms of instrumentation and would help establish the existence of the most reliable method of optometrically evaluating intra-ocular tension.