Haptic Detection of Artificial Tumors by Hand and with a Tool in a MIS Environment.

Minimally invasive surgery uses optical cameras and special surgical tools in order to operate from an environment one step removed from the body cavity of interest to the surgeon. It has been suggested that constraints posed by this arrangement, in particular the lack of direct haptic feedback to the surgeon, may affect the surgeon's ability to identify tissues and accurately maneuver inside the body cavity. In the present study, the ability of laypeople to detect artificial tumors of various hardness values embedded in silicone gels was assessed in a simulated MIS environment. Participants explored the gels under three conditions all with remote viewing; using the unrestricted bare finger, using a stick-like surgical tool also unrestricted, and using the surgical tool restricted by its insertion through an operating port as in MIS. Participants were significantly more accurate and more efficient at tumor detection with the finger as compared to the other methods of exploration, and they were also better at detecting harder tumors as compared to softer ones. The potential implications of these results for the role of haptic perception in minimally invasive surgery are discussed.

Children's haptic and cross-modal recognition with familiar and unfamiliar objects.

Five-year-old children explored multidimensional objects either haptically or visually and then were tested for recognition with target and distractor items in either the same or the alternative modality. In Experiments 1 and 2, haptic, visual, and cross-modal recognition were all nearly with familiar objects; haptic and visual recognition were also excellent with unfamiliar objects, but cross-modal recognition was less accurate. In Experiment 3, cross-modal recognition was also less accurate than within-mode recognition with familiar objects that were members of the same basic-level category. The results indicate that children's haptic recognition is remarkably good, that cross-modal recognition is otherwise constrained, and that cross-modal recognition may be accomplished differently for familiar and unfamiliar objects.

The spatial coding strategies of one-year-old infants in a locomotor search task.

The ability of 1-year-old infants to remember the location of a nonvisible target was investigated in 3 experiments. Infants searched for a toy hidden in one of many possible locations within a circular bounded space. The presence, number, and spatial arrangement of local cues or "landmarks" within this space were varied. The results of Experiment 1 showed that search performance was highly successful when a landmark was coincident with the location of the toy ("direct"), but less successful when a landmark was adjacent to the target location ("indirect"). The results of Experiment 2 suggested that search with an indirect landmark may be more fragile than search with no landmarks at all. In Experiments 3a and 3b, 2 different configurations of indirect landmarks were employed; search performance was equally poor with both of these and was inferior to search with no landmarks. It is concluded that infants of this age are able to associate a nonvisible target with a direct landmark and are able to code the distance and direction of a target with respect to themselves or with respect to the larger framework. However, there was no evidence that they can code the distance and direction of a target relative to another object. The difficulty of coding with indirect landmarks is interpreted in terms of cognitive complexity and conflict between spatial strategies.

Motor development and the mind: the potential role of motor abilities as a determinant of aspects of perceptual development.

Recent advances in the science of human movement have enabled developmental psychologists to discover unique patterns of organization and control in infant motor behavior and development, provoking a resurgence of interest in this topic. In this article, we emphasize the role that motor development may play in determining developmental sequences or "timetables" in other domains. Specifically, we argue that particular motor achievements may be integral to developments in the domains of haptic perception and depth perception. In both cases, there is a high degree of fit between the developmental sequence in which certain perceptual sensitivities unfold and the ages at which the corresponding motor abilities onset. The discussions may provide new contexts in which to consider the developments of haptic perception and depth perception. The general purpose, however, is to highlight the wide-ranging influence of motor development during infancy.

The perception of identity by 6 1/2-month-old infants.

In Study 1, sixteen 6 1/2-month-olds were habituated to a Reversible stimulus (an upright face that could be perceived as an entirely different upright face when it was rotated 180 degrees) and to a Nonreversible stimulus (a face that could be perceived as upright in only one orientation). Following habituation for each type of stimulus, test trials paired the habituated face with a novel stimulus (an inversion of the same face). For both Reversible and Nonreversible stimuli, the physical difference between the old and new test stimuli was the same (a 180 degrees rotation); however, infants devoted more visual attention to the 180 degrees rotation only when it was a Reversible face, suggesting that the identity change was detected. Experiment 2 ruled out the explanation that infants might have failed to dishabituate to the inversion of the Nonreversible stimulus because they could not remember it. Results are interpreted as evidence that 6 1/2-month-old infants are not limited to face recognition based on similarity in pattern arrangement alone, but are capable of processing faces at a representational level.

Infants' detection of visual-tactual discrepancies: asymmetries that indicate a directive role of visual information.

Infants' cross-modal functioning was investigated in two studies. In Study 1, 11-month-old infants were confronted with five different visual-tactual discrepancies created with a mirror arrangement. The infants' behavioral reactions to the discrepancies were compared with their behavior on matched control trials with a forced-choice judgement procedure. Infants detected discrepancies in which they saw an egg and felt a cube, saw a fur-covered cube and felt an egg, and saw a cross and felt a fur-covered cube. However, they provided no evidence that they detected discrepancies in which they saw a cube and felt a cross or saw a cube and felt a fur-covered cube. In Study 2, infants were confronted with discrepancies that were the converse of those which seemed to go unnoticed in Study 1: They saw either a cross or a fur-covered cube and felt a plain cube. Both of these new discrepancies were detected according to the forced-choice judgment procedure. The results indicate that texture as well as shape can serve as a basis for cross-modal matching for infants. The asymmetries in cross-modal matching that were observed across Studies 1 and 2 are interpreted as evidence that visual information plays a directive, goal-setting role for infants' manual explorations.

Spooning and basketing: children's dealing with accidental gaps in the lexicon.

The abilities of 2-, 5-, and 7-year-old children to interpret, judge the acceptability of, and produce class extensions were assessed. Class extensions are linguistic constructions in which a word that normally functions as a member of one syntactic category is used as a member of another, as in the sentence He is pianoing Christmas songs. Subjects in each age group understood sentences containing class extensions to some extent. However, the 2-year-olds' performance was depressed relative to the near-maximal performance of the older subjects, because they were generally insensitive to word-order cues in the stimulus sentences. Only the 7-year-olds consistently judged sentences containing class extensions to be deviant; the 5-year-olds confused syntax and semantics in making their judgments. The 7-year-olds were also able to produce class-extension phrases "on demand" more frequently than the 5-year-olds. It is concluded that the increasing ability with age to deal appropriately with class extensions is primarily due to general advances in language acquisition rather than to any development unique to the class-extension word-formation process. It is noted that the pattern of results reported, as well as observations that children's use of class extensions in spontaneous speech declines with age, may both be accounted for if word-formation rules are assumed to be "nonproductive, general rules," with a generative component and a later-acquired inhibitory component.

The development of anticipatory hand orientation during infancy.

The development of infants' prehensile adjustments regarding the orientation of objects was investigated. Five- and nine-month-olds (N = 16 per group) were presented with horizontally and vertically oriented dowels to determine at what point during the reach, hand orientation approximated that of the dowel. Nine-month-olds rotated their hands appropriately, early in the course of the reach, i.e., before tactual contact of the dowel, whereas five-month-olds did so mostly after tactual contact. Analyses of the effects of trials within the experimental session indicated that this age difference was not associated with practice or fatigue effects. The results are discussed in relation to the development of visual control of prehensile behavior.

Infant visual acuity as a function of viewing distance.

Dynamic retinoscopy has suggested that near vision may be more acute than far vision during early infancy. To test this, acuity thresholds were determined by presenting square wave gratings in a preference paradigm to 1- and 2-month-old human infants at 4 viewing distances. Gratings were paired with unpatterned fields; direction of first fixation was the dependent measure. Infants exhibited the same acuity at each of the distances at which gratings were presented. The results were interpreted as compatible with the fact that considerable optical defocusing does not seriously affect a visual system, such as the infant's, that is sensitive only to low spatial frequencies.