Material evidence: interaction of well-learned priors and sensorimotor memory when lifting objects

2012 ◽  
Vol 108 (5) ◽  
pp. 1262-1269 ◽  
Author(s):  
Lee A. Baugh ◽  
Michelle Kao ◽  
Roland S. Johansson ◽  
J. Randall Flanagan
Keyword(s):  
Rate Of Change ◽  
Core Material ◽  
Load Force ◽  
Small Object ◽  
Surface Material ◽  
Phase Duration ◽  
Material Density ◽  
Small Cube ◽  
Object Weight ◽  
Sensorimotor Memory

Skilled object lifting requires the prediction of object weight. When lifting new objects, such prediction is based on well-learned size-weight and material-density correlations, or priors. However, if the prediction is erroneous, people quickly learn the weight of the particular object and can use this knowledge, referred to as sensorimotor memory, when lifting the object again. In the present study, we explored how sensorimotor memory, gained when lifting a given object, interacts with well-learned material-density priors when predicting the weight of a larger but otherwise similar-looking object. Different groups of participants 1st lifted 1 of 4 small objects 10 times. These included a pair of wood-filled objects and a pair of brass-filled objects where 1 of each pair was covered in a wood veneer and the other was covered in a brass veneer. All groups then lifted a larger, brass-filled object with the same covering as the small object they had lifted. For each lift, we determined the initial peak rate of change of vertical load-force rate and the load-phase duration, which provide estimates of predicted object weight. Analysis of the 10th lift of the small cube revealed no effects of surface material, indicating participants learned the appropriate forces required to lift the small cube regardless of object appearance. However, both surface material and core material of the small cube affected the 1st lift of the large block. We conclude that sensorimotor memory related to object density can contribute to weight prediction when lifting novel objects but also that long-term priors related to material properties can influence the prediction.

scholarly journals Quantifying feedforward control: a linear scaling model for fingertip forces and object weight

2015 ◽  
Vol 114 (1) ◽  
pp. 411-418 ◽  
Author(s):  
Ying Lu ◽  
Seda Bilaloglu ◽  
Viswanath Aluru ◽  
Preeti Raghavan
Keyword(s):  
Feedforward Control ◽  
Peak Load ◽  
Rate Of Change ◽  
Load Force ◽  
Healthy Individuals ◽  
Object Weight ◽  
Custom Made ◽  
Precise Relationship ◽  
Log Linear ◽  
Fingertip Forces

The ability to predict the optimal fingertip forces according to object properties before the object is lifted is known as feedforward control, and it is thought to occur due to the formation of internal representations of the object's properties. The control of fingertip forces to objects of different weights has been studied extensively by using a custom-made grip device instrumented with force sensors. Feedforward control is measured by the rate of change of the vertical (load) force before the object is lifted. However, the precise relationship between the rate of change of load force and object weight and how it varies across healthy individuals in a population is not clearly understood. Using sets of 10 different weights, we have shown that there is a log-linear relationship between the fingertip load force rates and weight among neurologically intact individuals. We found that after one practice lift, as the weight increased, the peak load force rate (PLFR) increased by a fixed percentage, and this proportionality was common among the healthy subjects. However, at any given weight, the level of PLFR varied across individuals and was related to the efficiency of the muscles involved in lifting the object, in this case the wrist and finger extensor muscles. These results quantify feedforward control during grasp and lift among healthy individuals and provide new benchmarks to interpret data from neurologically impaired populations as well as a means to assess the effect of interventions on restoration of feedforward control and its relationship to muscular control.

Size–Weight Illusion, Anticipation, and Adaptation of Fingertip Forces in Patients With Cerebellar Degeneration

2009 ◽  
Vol 101 (2) ◽  
pp. 569-579 ◽  
Author(s):  
K. Rabe ◽  
B. Brandauer ◽  
Y. Li ◽  
E. R. Gizewski ◽  
D. Timmann ◽  
...  
Keyword(s):  
Cerebellar Degeneration ◽  
Load Force ◽  
Control Group ◽  
Equal Weight ◽  
Small Object ◽  
Large Object ◽  
Object Weight ◽  
And Gender ◽  
Weight Illusion ◽  
Fingertip Forces

The smaller of two equally weighted objects is judged to be heavier when lifted (size–weight illusion [SWI]). In contrast, fingertip forces show an initial size effect but adapt to the true object weights within a few trials. The aim of this study was to investigate possible contributions of the cerebellum to SWI, force anticipation, and adaptation based on object size and weight. Eighteen participants with isolated cerebellar degeneration and 18 age- and gender-matched controls alternately lifted objects of equal weight but different size in 40 trials. All participants perceived the small object to be heavier after lifting (perceptive SWI). Fingertip forces were significantly higher during the first lift of the large object compared with the small object in the control and cerebellar groups. For the load-force rate and lifting acceleration, effects of anticipation were significantly less in the cerebellar compared with the control group. Grip and load forces were adapted to object weight during repeated lifts in both groups. Preserved perceptive SWI in cerebellar patients supports the hypothesis that perceptive SWI depends on the function of the ventral visual path that receives no or few efferents from the cerebellum. The findings of preserved anticipation and adaptation of grip forces in cerebellar patients, however, were unexpected. Reduced anticipation of load forces suggests that the neural presentation of predictive grip- and load-force control may be different. Findings show that representation and adaptation of internal models of object characteristics are not exclusively located in the cerebellum.

Impaired Grip Force Modulation in the Ipsilesional Hand after Unilateral Middle Cerebral Artery Stroke

2005 ◽  
Vol 19 (4) ◽  
pp. 338-349 ◽  
Author(s):  
Barbara M. Quaney ◽  
Subashan Perera ◽  
Rebecca Maletsky ◽  
Carl W. Luchies ◽  
Randolph J. Nudo
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Cognitive Deficits ◽  
Grip Force ◽  
Precision Grip ◽  
Load Force ◽  
Cutaneous Sensation ◽  
Sensorimotor Processing ◽  
Object Weight ◽  
Stroke Group

Understanding grasping control after stroke is important for relearning motor skills. The authors examined 10 individuals (5 males; 5 females; ages 32-86) with chronic unilateral middle cerebral artery (MCA) stroke (4 right lesions; 6 left lesions) when lifting a novel test object using skilled precision grip with their ipsilesional (“unaffected”) hand compared to healthy controls (n = 14; 6 males; 8 females; ages 19-86). All subjects possessed normal range of motion, cutaneous sensation, and proprioception in the hand tested and had no apraxia or cognitive deficits. Subjects lifted the object 10 times at each object weight (260 g, 500 g, 780 g) using a moderately paced self-selected lifting speed. The normal horizontal (“grip”) force and vertical tangential (“lift”) force were separately measured at the thumb and index finger. Regardless of the object weight or stroke location, the stroke group generated greater grip forces at liftoff of the object (≥ 39%; P ≤ 0.05) and across the dynamic (P ≤ 0.05) and static portions (P ≤ 0.05) of the lifts compared to the healthy group. Peak lift forces were equivalent between groups, suggesting accurate load force information processing occurred. These results warrant further investigation of altered sensorimotor processing or compensatory biomechanical strategies that may lead to inaccurate grip force execution after strokes.

scholarly journals Infants’ prospective control during object manipulation in an uncertain environment

2018 ◽  
Author(s):  
Janna M. Gottwald ◽  
Gustaf Gredebäck
Keyword(s):  
Motion Capture ◽  
Visual Information ◽  
Color Condition ◽  
Significant Interaction Effect ◽  
Prospective Control ◽  
Object Weight ◽  
Sensorimotor Memory ◽  
Sensorimotor Information ◽  
Different Color ◽  
Movement Unit

This study investigates how infants use visual and sensorimotor information to prospectively control their actions. We gave 14-month-olds two objects of different weight and observed how high they were lifted, using a Qualisys Motion Capture System. In one condition, the two objects were visually distinct (different color condition) in another they were visually identical (same color condition). Lifting amplitudes of the first movement unit were analyzed in order to assess prospective control. Results demonstrate that infants lifted a light object higher than a heavy object, especially when vision could be used to assess weight (different color condition). When being confronted with two visually identical objects of different weight (same color condition), infants showed a different lifting pattern than what could be observed in the different color condition, expressed by a significant interaction effect between object weight and color condition on lifting amplitude. These results indicate that (a) visual information about object weight can be used to prospectively control lifting actions and that (b) infants are able to prospectively control their lifting actions even without visual information about object weight. We argue that infants, in the absence of reliable visual information about object weight, heighten their dependence on non-visual information (tactile, sensorimotor memory) in order to estimate weight and pre-adjust their lifting actions in a prospective manner.

scholarly journals Sensorimotor Memory for Object Weight is Based on Previous Experience During Lifting, Not Holding

2018 ◽  
Author(s):  
Vonne van Polanen ◽  
Marco Davare
Keyword(s):  
Motor Command ◽  
Object Manipulation ◽  
Recent Experience ◽  
List Type ◽  
Holding Period ◽  
Object Weight ◽  
Object Lifting ◽  
Time Period ◽  
Sensorimotor Memory ◽  
Force Planning

ABSTRACTTo allow skilled object manipulation, the brain must generate a motor command specifically tailored to the object properties. For instance, in object lifting, the forces applied by the fingertips must be scaled to the object’s weight. When lifting a series of objects, forces are usually scaled according to recent experience from previously lifted objects, an effect often referred to as sensorimotor memory. In this study, we investigated the specific time period during which stored information from previous object manipulation is used to mediate sensorimotor memory. More specifically, we examined whether sensorimotor memory was based on weight information obtained between object contact and lift completion (lifting phase) or during stable holding (holding phase). Participants lifted objects in virtual reality that could increase or decrease in weight after the object was lifted and held in the air. In this way, we could distinguish whether the force planning in the next lift was scaled depending on weight information gathered from either the dynamic lifting or static holding period. We found that force planning was based on the previous object weight experienced during the lifting, but not holding, phase. This suggest that the lifting phase, while merely lasting a few hundred milliseconds, is a key time period for building up internal object representations used for planning future hand-object interactions.HIGHLIGHTSWhen lifting objects, fingertip force scaling is based on the most recent liftWe investigated what time period is critical for acquiring sensorimotor memorySensorimotor memory is based on weight experienced during previous lift, not holdThe lifting phase is a key period for building up internal models of object lifting

scholarly journals COMPARISON OF PIXEL-BASED AND FEATURE-BASED APPROACH FOR SMALL OBJECT CHANGE DETECTION

2021 ◽  
Vol XLIII-B3-2021 ◽  
pp. 353-357
Author(s):  
J. Seo ◽  
T. Kim
Keyword(s):  
Change Detection ◽  
Satellite Images ◽  
Rate Of Change ◽  
Image Resolution ◽  
Detection Methods ◽  
Small Object ◽  
Feature Points ◽  
Detection Algorithms ◽  
Change Detection Algorithms ◽  
Feature Based

Abstract. Satellite image resolution has evolved to daily revisit and sub-meter GSD. Main targets of previous remote sensing were forest, vegetation, damage area by disasters, land use and land cover. Developments in satellite images have brought expectations on more sophisticated and various change detection of objects. Accordingly, we focused on unsupervised change detection of small objects, such as vehicles and ships. In this paper, existing change detection methods were applied to analyze their performances for pixel-based and feature-based change of small objects. We used KOMPSAT-3A images for tests. Firstly, we applied two change detection algorithms, MAD and IR-MAD, which are most well-known pixel-based change detection algorithms, to the images. We created a change magnitude map using the change detection methods. Thresholding was applied to determine change and non-change pixels. Next, the satellite images were transformed as 8-bit images for extracting feature points. We extracted feature points using SIFT and SURF methods to analyze feature-based change detection. We assumed to remove false alarms by eliminating feature points of non-changed objects. Therefore, we applied a feature-based matcher and matched feature points on identical image locations were eliminated. We used non-matched feature points for change/non-change analysis. We observed changes by creating a 5x5 size ROI around extracted feature points in the change/non-change map. We determined that change has occurred on feature points if the rate of change pixels with ROI was more than 50%. We analyzed the performance of pixel-based and feature-based change detection using ground truths. The F1-score, AUC value, and ROC were used to compare the performance of change detection. Performance showed that feature-based approaches performed better than pixel-based approaches.

Fibrous Material Density Difference Analysis Using Light Reflectance

2014 ◽  
Vol 487 ◽  
pp. 114-117
Author(s):  
Ong Tee Say ◽  
Zaliman Sauli ◽  
Vithyacharan Retnasamy ◽  
K. Anwar ◽  
Nooraihan Abdullah
Keyword(s):  
Fibrous Material ◽  
Laser Light ◽  
Surface Material ◽  
Material Density ◽  
Voltage Output ◽  
Reflected Light ◽  
Light Reflectance ◽  
Printing Paper ◽  
Laser Light Source

The objective of this work is designed and fabricated a lab module tester to differentiate the different type of printing paper quality which available commercially was done. Laser light source was used to differentiate the quality of printing paper. The concept light reflectance on surface material was used in this study. The photodiode was used as photo detector to detect the reflected light from the surface of printing paper. The laser diode and photodiode were placed in a box which the box named light box. The laser was used to emit light on the sample and the photodiode detects light intensity from the surface printing paper in the light box. Different level of intensity will have different value of voltage output. The differentiation on the different type of printing paper including of 70 g/m2, 80 g/m2 and 100 g/m2 were done respectively. The result showed that the 100 g/m2 printing paper has a higher reflected voltage output compared to 80 g/m2 and 70 g/m2 printing paper.

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