Experimental validation of an optimization formulation of the human grasping quality sense

An experimental procedure that evaluates the quality of a grasp is developed. In this procedure human subjects grasp a rigid object that is subjected to an external load. Three formulations that capture the sense of grasping quality through the energy level stored in the gripper, maximum value of the applied finger forces, and through the distribution of the grasping forces are considered. The applied finger forces are measured and the quality values of the grasp based on these three different formulations are computed. These grasping quality values are compared with numerical human assessments, that are obtained via a psychophysical magnitude estimation method. We derive an augmented weighted functional that combines these three formulations, and show that it exhibits a high correlation with human quality assessment. Our results demonstrate that the most dominant mechanism that characterizes the quality of a rigid body grasp is the uniformity level of the contact forces. © 1997 John Wiley & Sons, Inc.     

Across-notation automatic numerical processing.

In this article, the authors explored the existence of across-notation automatic numerical processing using size comparison and same-different paradigms. Participants were Arabic speakers, who used 2 sets of numerical symbols--Arabic and Indian. They were presented with number pairs in the same notation (Arabic or Indian) or in different ones (Arabic and Indian). In the size comparison paradigm, 2 digits differing both numerically and physically were compared on the physical dimension. Nevertheless, there was evidence that participants automatically processed the irrelevant numerical dimension in different notation pairs. In the same-different paradigm, 2 digits were presented either in the same or in different notations. Participants had to indicate whether the 2 digits were physically the same. The results again showed evidence for the automatic processing of numerical magnitude for pairs in different notations. Findings of both experiments suggest that numbers in different notations are automatically translated into a common representation of magnitude, in line with M. McCloskey's (1992) abstract representation model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controlling Stroop interference: Evidence from a bilingual task.

Skilled performance is often associated with automaticity. Automatic processes are generally thought of as uncontrollable so that automaticity implies the lack of control. The Stroop Color and Word Test is one of the most cited examples of automaticity and uncontrollability of word reading. This task is also employed extensively to investigate the structure of the bilingual lexicon. The present work employed a Hebrew-Arabic bilingual Stroop task in 2 separate experiments. To induce controlled processing, the authors varied the Ss' expectations regarding the written (irrelevant) color words. The Stroop interference effect was always present, but Ss were able to control (reduce) it in their native language but not in their second language. In addition, the presumed structure of the bilingual lexicon seems to change in accordance with proficiency in the second language. It is suggested that automaticity and control are both characteristics of skilled performance with each of them reflecting a different aspect and each subserving a different function of our cognitive system. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic and intentional processing of numerical information.

Ss evaluated either numerical size or physical size of stimuli varying along both dimensions. Size congruity, distance, and semantic congruency effects were obtained for numerical comparisons of digit pairs and for comparisons of digits with an internal standard (5). Only the size congruity effect was obtained for physical judgments. It was smaller for pairs in which both stimuli were either both smaller or both larger than 5 than for pairs that contained the digit 5. The results are consistent with the notion that intentional processing is mainly algorithm-based, whereas autonomous processing is mainly memory-based. Implications of the results for models of numerical processing are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Exploring the mental number line via the size congruity effect.

To address the ongoing debate about the origins of the size effect (faster comparison time for smaller than larger numbers, given a fixed intrapair distance), an indication of automatic number processing was searched for. Participants performed a quantity comparison task in which they had to decide which of two sketched cups contained more liquid, while ignoring the number superimposed on each cup. In the congruent condition, the larger number appeared on the cup containing more liquid, while in the incongruent condition the larger number appeared on the cup containing less liquid. The size effect was found in a numerical comparison task, while in the quantity comparison task the size congruity effect decreased as the magnitude of the irrelevant numbers increased. Together, these results suggest that the size effect reflects a basic feature of the mental number line. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the recognition of words with inverted letters.

Conducted 2 experiments in which 24 Ss were asked to identify words with all or some of their letters inverted. The experiments differed only in the explicitness of the instructions given to Ss. In some cases the letters appearing upside down were inverted as 1 unit, and in other cases they were inverted by letter. It was found that when all the letters were inverted, recognition time was faster for unit inversion. When just a few of the letters in the words were inverted, recognition time was shorter when the inversion was letter by letter rather than by unit. Data are consistent with a model that assumes that when the stimulus is homogeneously misoriented unit correction is applied, and when such homogeneity does not exist piecemeal correction is applied. (French abstract) (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A generalized fraction: An entity smaller than one on the mental number line.

The representation of fractions in long-term memory (LTM) was investigated by examining the automatic processing of such numbers in a physical comparison task, and their intentional processing in a numerical comparison task. The size congruity effect (SiCE) served as a marker of automatic processing and consequently as an indicator of the access to the primitives of numerical representation in LTM. Mixed pairs composed of a natural number and a fraction showed both a SiCE and a distance effect. The SiCE for mixed pairs was stable across relative sizes of natural numbers compared to the fraction digits (Experiment 4). However, comparing pairs of fractions revealed a strong influence of fractional components: An inverse SiCE was found for pairs of unit fractions (Experiment 1), while no SiCE was found for pairs of non-unit fractions (Experiments 2–3). This leads to the conclusions that: (1) there are no unique representations of distinct fraction values in LTM, and (2) there is a representation of a “generalized fraction” as an “entity smaller than one” that emerges from the notational structure common to all fractions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automatic comparisons of artificial digits never compared: Learning linear ordering relations.

In 2 experiments, participants were trained to perform magnitude decisions, that is, decide which of 2 arbitrary symbols in a pair represented a larger magnitude. The symbols corresponded to locations on an implicit linear scale. Training resulted in a Stroop-like size congruity effect when the participants had to decide which symbol in a pair was physically larger. This effect, showing automaticity of the processing of magnitude relations, was also obtained for pairs never encountered during practice. The implications of these findings for processing of magnitude relations and for theories of automaticity are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)