Spatial constraints and regulatory functions in monkeys' (Cebus apella) search.

By means of an apparatus featuring a set of suspended baited containers, search abilities of 4 capuchin monkeys (Cebus apella) were evaluated. The experiment featured different spatial configurations of the search space. Results showed that monkeys exhaustively searched 9 containers spatially distributed as a 3?×?3 matrix, a cross, a line, or a circle. Search efficiency was higher when the search space featured either a linear or circular arrangement of containers. When faced with a linear arrangement of containers, the subjects developed principled search trajectories from 1 end to the other of the linear array. This behavioral regulation was independent from search efficiency as measured by the amount of visits to containers already explored. The data suggest that monkeys use either the travel distance or the cognitive costs associated with unprincipled travel trajectories as currency for regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning to cope with two different food distributions: The performance of house mice (Mus musculus domesticus).

Search abilities of mice (Mus musculus domesticus) were evaluated using an arena closed by a ceiling in which 9 food sources (which mice could reach standing on their hind legs) could be arranged according to 2 configurations: a 3?×?3 square matrix and 3 clusters each containing 3 food sources. Testing conditions prevented olfactory and visual cues from being left after visits to food sources, and mice were able to choose alternative routes between food sources. Results showed that mice were more efficient with the matrix than with the cluster configuration. Sex differences were observed: Females improved their performance with both configurations, whereas males improved only with the matrix one. Mice did not develop evident search strategies that would minimize task complexity. Comparison with data published on capuchin monkeys revealed differences, with monkeys performing better with the cluster configuration than with the matrix and applying searching strategies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Automated Path Planning of Cooperative Crane Lifts Using Heuristic Search

The use of cooperative cranes can improve the cost effectiveness of heavy lift operations. However, the complexity in developing a reliable lift plan prevents the widespread use of cooperative crane lifts. The availability of a computer-aided planning system can improve planning efficiency and reliability. Path planning is an important subtask of the lift planning process. This paper presents work done to develop a computer aided path planner for two crane lifts. Two heuristic search methods, hill climbing and A?, were implemented for automating the path-planning task. Search space was represented using the concept of configuration space. The effectiveness of the search methods was evaluated by solving three problems with increasing levels of complexity. The formulation of these problems was based on the type of movement of cooperative cranes (in synchronous or asynchronous manner) and the presence of trapping space. It was found that while the hill climbing approach found feasible paths in a few seconds or minutes, these paths were far from optimal in situations containing trapping space. In contrast, the A? search resulted in near optimal paths, but the execution time was of the order of hours.     

The role of visual and body movement information in infant search.

Three experiments investigated the use of visual input and body movement input arising from movement through the world on spatial orientation. Infants between 9.5 and 18 months participated in a search task in which they searched for a toy hidden in 1 of 2 containers. Prior to beginning search, either the infants or the containers were rotated 180*; these rotations occurred in a lit or dark environment. These experiments were distinguished by the environmental cues for object location; Experiment 1 used a position cue, Experiment 2 a color cue, and Experiment 3 both position and color cues. Accuracy was better in Experiments 2 and 3 than in Experiment 1. All studies found that search was best after infant movement in the light; all other conditions led to equivalently worse performance. These results are discussed relative to a theoretical characterization of spatial coding focusing on the uses of spatial information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Training squirrel monkeys (Saimiri sciureus) to deceive: Acquisition and analysis of behavior toward cooperative and competitive trainers.

Three squirrel monkeys (Saimiri sciureus) learned to reach toward a container that covered food if a cooperative trainer rewarded such reaches by giving the food. A competitive trainer kept any food found, but wrong selections by this trainer were also rewarded. The monkeys initially reached toward the baited container indiscriminately, but gradually and with the aid of color-cued containers, all 3 reliably reached "honestly" and "deceptively" in the presence of the cooperative and competitive trainers, respectively. The monkeys did not appear to take the trainers' knowledge about the location of the food into account, and deception did not occur if food was placed under the normally unbaited container. With additional containers present, monkeys misled the competitive trainer into selecting the unbaited container farthest from the baited one. Although not indicative of mental attribution, the monkeys' behavior suggests awareness of the acquired communicative function of the reaching response. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Modifying guided search: Preattentive object files.

Many models of visual search behaviour consist of a first stage in which basic features are processed "in parallel" at all locations across the visual field and a second, limited-capacity stage in which processing is restricted to a single item or location. Perhaps the best known of these models is Feature Integration Theory (FIT) (e.g. Treisman, 1993). The original FIT was the starting point for our Guided Search (Wolfe, 1994). The heart of Guided Search is the proposal that the parallel first stage can guide the spatial deployment of the limited resources of the second stage. For example, consider a conjunction search for a red vertical line among green vertical lines and red horizontal lines. There is good reason to believe that no first stage mechanism is specifically designed to be sensitive to conjunctions of colour and orientation. Nevertheless, searches for conjunctions of this sort are quite efficient; more efficient than they ought to be if second stage resources were deployed from item to item in a random, serial search. This efficiency can be obtained if information is combined from two first stage feature processors. If a colour processor guides attention toward all red items while an orientation processor guides all attention toward the vertical items, attention would be guided most strongly toward the red vertical items. Even if we assume that guidance is not perfect, the combination of these two sources of information will make the search for a conjunction more efficient that it would have been in the absence of guidance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Use of olfactory cues in foraging by owl monkeys (Aotus nancymai) and capuchin monkeys (Cebus apella).

The authors tested free-ranging New World monkeys (nocturnal owl monkeys [Aotus nancymai] and diurnal capuchin monkeys [Cebus apella]) to determine the extent to which they use olfactory cues to locate food hidden in containers at 2 of 6 feeding sites within a 1?-ha forested enclosure. These 2 sites were selected randomly for each trial and then were baited with banana and banana peel residue. The 4 other sites were unbaited and unscented. In trials in which the food was not visible to the monkeys, Aotus monkeys located the baited sites at a level greater than expected by chance, whereas Cebus monkeys did not. Use of olfactory information by Aotus monkeys in foraging may be an adaptation for nocturnal foraging because olfactory cues are more salient than visual cues at low light levels. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Storage and retrieval processes of alcohol-induced amnesia.

Used a technique that separates storage from retrieval in the Peterson paradigm to study the information-processing dynamics of alcohol-induced amnesia. An experiment with a 2–3 factorial design was performed with 38 normal male undergraduates; the factors were (a) drug group (632 ml/kg alcohol vs placebo), (b) organization (high vs low organization of target items), and (c) retention interval (4 sec vs 12 sec). Results show that the storage measure, all main effects and the Organization?×?Retention Interval interaction were significant. For the retrieval measure, all main effects and interactions were significant except the Drug Group?×?Retention Interval interaction. Because the storage and retrieval measures were independent, a 2-process explanation of alcohol-induced memory impairment is developed, using the theoretical notions of "depth of encoding" and "restriction of search set." Some clinical implications are discussed. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A neural theory of attentive visual search: Interactions of boundary, surface, spatial, and object representations.

Visual search data are given a unified quantitative explanation by a model of how spatial maps in the parietal cortex and object recognition categories in the inferotemporal cortex deploy attentional resources as they reciprocally interact with visual representations in the prestriate cortex. The model visual representations are organized into multiple boundary and surface representations. Visual search in the model is initiated by organizing multiple items that lie within a given boundary or surface representation into a candidate search grouping. These items are compared with object recognition categories to test for matches or mismatches. Mismatches can trigger deeper searches and recursive selection of new groupings until a target object is identified. The model provides an alternative to Feature Integration and Guided Search models. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conjunction search revisited.

Search for conjunctions of highly discriminable features can be rapid or even parallel. This article explores three possible accounts based on (a) perceptual segregation, (b) conjunction detectors, and (c) inhibition controlled separately by two or more distractor features. Search rates for conjunctions of color, size, orientation, and direction of motion correlated closely with an independent measure of perceptual segregation. However, they appeared unrelated to the physiology of single-unit responses. Each dimension contributed additively to conjunction search rates, suggesting that each was checked independently of the others. Unknown targets appear to be found only by serial search for each in turn. Searching through 4 sets of distractors was slower than searching through 2. The results suggest a modification of feature integration theory, in which attention is controlled not only by a unitary "window" but also by a form of feature-based inhibition. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interrupted visual searches reveal volatile search memory.

This study investigated memory from interrupted visual searches. Participants conducted a change detection search task on polygons overlaid on scenes. Search was interrupted by various disruptions, including unfilled delay, passive viewing of other scenes, and additional search on new displays. Results showed that performance was unaffected by short intervals of unfilled delay or passive viewing, but it was impaired by additional search tasks. Across delays, memory for the spatial layout of the polygons was retained for future use, but memory for polygon shapes, background scene, and absolute polygon locations was not. The authors suggest that spatial memory aids interrupted visual searches, but the use of this memory is easily disrupted by additional searches. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How do tufted capuchin monkeys (Cebus apella) understand causality involved in tool use?

Four tufted capuchin monkeys (Cebus apella) were trained to choose from 2 hook-like tools, 1 of which successfully led to collecting food, whereas the other did not because of inappropriate spatial arrangement of the tool and the food. In Experiment 1, all of the monkeys successfully learned the basic task. The monkeys performed successfully with tools of novel colors and shapes in Experiments 2-5. These results demonstrate that the monkeys used the spatial arrangement of the tool and the food as a cue. However, they failed when there were obstacles (Experiment 6) or traps (Experiment 7) on the path along which she monkeys dragged tools. These results may suggest that capuchin monkeys understand the spatial relationship between 2 items, namely, food and. the tool, but do not understand the spatial relationship among 3 items, namely, food, tool, and the environmental condition. The possible role of stimulus generalization is also considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

What facial part is important for Japanese monkeys (Macaca fuscata) in recognition of smiling and sad faces of humans (Homo sapiens)?

Four Japanese monkeys (Macaca fuscata) and 17 humans (Homo sapiens) performed an odd-item visual search task of a variety of photos of human facial expressions. The target was either a genuine smiling face or a sad face of a female. The distracters were the following artificial images produced by a computerized image processing system: (a) a neutral face made by averaging the 2 targets or (b) faces with smiling or sad eyebrows, eyes, cheeks, or mouth on the neutral face. The search reaction time of both species was the longest when they had to find the smiling target among the distracters having the smiling cheeks. In searching for the sad target, however, the reaction time of humans was the longest when the distracters had sad eyebrows or sad cheeks, whereas the longest reaction time for monkeys was when the distracters had sad cheeks. These results indicate that monkeys search smiling human faces as humans do, but monkeys do not use eyebrows as a cue to search sad human faces. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Search and retrieval patterns for performance information: Effects on evaluations of multiple targets.

Examined search, organization, and use of performance information about multiple targets. In Exp I, 41 undergraduates searched among 64 performance vignettes, stored in a 4?×?4?×?4 (Target?×?Task?×?Occasion) computer array. The predominant search pattern involved examining a set of performances by one target before proceeding to another. Exp II tested whether various acquisition patterns affect organization and use of performance information. 125 Ss were shown 16 vignettes from Exp I, organized in target-by-target (target blocked), task-by-task (task blocked), or mixed sequences. Results indicate greater recall under blocked than under mixed conditions. Blocking also influenced organization in recall. Target blocking produced clustering by target; task blocking produced clustering by task; mixed presentation produced no discernible clustering. Accuracy of ratings for overall target performance was unaffected by blocking, but task blocking produced better differentiation among instances of good and poor performance exhibited by specific targets. (22 ref) (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Overt orienting in the rat: Parametric studies of cued detection of visual targets.

Covert shifts of visual attention in space have been quantified by measuring the effects of visual cues on the detection of visual targets in humans and monkeys maintaining visual fixation. These observations of "covert orienting" have provided important information regarding the neurobiology of visual attention in primates. This article describes a cued spatial target detection task for physically unrestrained rats. Valid cues (spatially contiguous with the target) enhanced target detection, and invalid cues (spatially discontiguous with the target) degraded target detection. Both visual and auditory cues were effective. These validity effects could not be explained by stimulus additivity or response preparation mechanisms, whereas a cue-independent "alerting effect" appeared to reflect response preparation. The effects compare favorably with primate work and suggest that this method may enable assessment of visual attention shifts in rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Lesioning a connectionist model of visual search: Selective effects on distractor grouping.

Presents a connectionist model of visual search, Search via Recursive Rejection (SERR) by G. W. Humphreys and H. J. Muller (in press), in which search is determined by patterns of grouping between distractors and between simple form elements. The performance of SERR is examined after it is subject to various types of "lesion." Lesioning is produced either by increasing the internal noise on the activation functions governing the interactions between processing units or by eliminating processing units from different loci in SERR. Simulations demonstrate that (1) search processes can be disrupted by adding internal noise to search functions, (2) there can be selective effects on grouping processes, and (3) these selective effects can be associated with different types of lesion to different stages in SERR. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Memory of monkeys (Macaca mulatta) with lesions in prefrontal cortex.

Three studies with 9 rhesus monkeys examined whether removal of the tissue of sulcus principalis affected Ss' memory for a list of spatial locations. Findings show that 3 Ss whose tissue in the sulcus principalis had been removed were no longer able to search effectively for food, relative to 3 unoperated controls, when given 25 spatial locations to remember. A less marked deficit was apparent in 3 Ss whose superior prefrontal convexity had been removed. Ss with sulcus principalis lesions learned as quickly as other Ss to choose between locations on the basis of a spatial cue, and they did not take significantly longer to shift from a previously rewarded location. Findings are considered in relation to the deficits observed in humans with unilateral frontal lesions and the possibility that frontal mechanisms operate on information in working memory. (55 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assessment of unilateral spatial neglect: Scoring star cancellation performance from video recordings—method, reliability, benefits, and normative data.

Unilateral spatial neglect, a debilitating condition affecting awareness of one side of space, is commonly assessed using cancellation tasks in which patients cross out targets distributed over a sheet. Standard scores emphasize the left–right distribution of omissions. Here, the additional value of extracting temporal as well as spatial aspects of performance from video recordings was examined. Videos from 18 patients with left neglect and 19 healthy age-matched control participants were obtained. Interrater reliability of the video analysis was high. In addition to overall differences in target detection and bias, patients significantly differed from the control group in terms of the location of first cancellation, overall slowness, greater variability in speed, systematic slowing with time on task and as a function of target location, less coherent search organization, and a sharply increased tendency to recancel targets. Considering a subset of patients whose scores, by standard criteria, were at or near the normal range indicated that these additional variables indeed increased the sensitivity of the task as well as allowed the simultaneous assessment of spatial and nonspatial aspects of the disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Display variability and spatial organization as contributors to the pigeon's discrimination of complex visual stimuli.

Three experiments assessed the contributions of display variability and spatial organization to the pigeon's discrimination of 16-icon visual displays. After training to discriminate 4?×?4 arrays of same and different computer icons, 4 pigeons were shown testing displays that systematically manipulated the variability of the depicted icons and their spatial organization on the display screen. Display variability and spatial organization each reliably controlled the pigeon's behavior. These seemingly separate effects could be collectively explained by the pigeon's discriminating the amount of variability or entropy in localized regions of the display. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of self-initiated locomotion on infant search activity.

Studied the ability of 26 10.3-11.2 mo old infants to search for a hidden object following self-initiated locomotion (SIL) or passive transportation to the search locations. Ss were trained to move independently 180° around a hiding box by crawling SIL and were carried 180° around a hiding box by a parent (other-initiated locomotion) before they were allowed to search for an object hidden in 1 of 2 locations. Results show that SIL produced more frequent correct object search than did other-initiated locomotion. Findings support Piaget's (1954) hypothesis that practical, action-based knowledge during infancy is involved in the achievement of spatial understanding and that the experience of SIL contributes to spatial development. It is argued that SIL fosters the infant's understanding of spatial relations because it (a) encourages the active revision of spatial relations that change with movement through space; (b) provides the opportunity to control the means-ends relation between actions and the achievement of a goal; and (c) contributes to a practical, action-based knowledge of object and self-relations in space. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)