Increased Search Time Research Articles

Interactions between Solenopsis invicta (Hymenoptera: Formicidae), Rhopalosiphum maidis (Homoptera: Aphididae), and the Parasitoid Lysiphlebus testaceipes Cresson (Hymenoptera: Aphidiidae)

In the presence of the red imported fire ant, Solenopsis invicta Buren, adult emergence of the parasitoid Lysiphlebus testaceipes Cresson from laboratory colonies of the corn leaf aphid, Rhopalosiphum maidis (Fitch), was reduced. Parasitoids abandoned an attack when ants were within a few millimeters and searched elsewhere, increasing search time. However, the increased searching time in the laboratory was compensated by a reduction in parasitoids' resting time resulting in similar levels of parasitism between the controls and the ant-infested containers. A major effect of the red imported fire ant was the removal and destruction of parasitized aphids. Ants began detecting parasitized aphids 6 d after parasitization and removed them to the ant colony. Honeydew production was reduced in parasitized aphids by 6 d and they resembled starved aphids. However, in contrast to parasitized aphids, starved aphids were moved to healthy plants, when available.

Human Performance Evaluation of Alternative Graphic Display Symbologies

Nonmilitary subjects learned each of two types of foreground symbol sets (conventional symbols and iconic symbols) and were then shown a series of computer displays containing various symbol configurations. Each subject was required to search for specified foreground symbols under the conditions of high and low density of symbols, restricted and nonrestricted search, and pictorial versus nonpictorial target-symbol presentation. Iconic symbols yielded faster search times than conventional symbols under the condition of nonrestricted search and under the condition of nonpictorial target symbol presentation. These results suggest that iconic symbols are both easier to locate and easier to recall from memory. In addition, regardless of the type of symbology, high-density display increased search times. It was concluded that a system that incorporates both iconic symbols and selective call-up on foreground information would likely result in optimal human performance on search-related tasks.

Resource selection by tropical frugivorous birds: integrating multiple interactions.

Resource selection is a function of interactions of organisms (competition, predation) as well as characteristics of the resource and organisms. I provide a quantitative model that integrates these factors. I use the model to predict profitability of fruits to tropical birds, but the model and its predictions are applicable to a wider array of systems and organisms. Profitability of a fruit is determined by rewards provided by the pericarp (mass and caloric yields) relative to costs (metabolic requirements, handling time, search time, behavioral interference, predator avoidance) associated with finding and eating that fruit (Fig. 1). Fruits increase in profitability with increases in fruit size until increases in handling time offset increases in pericarp mass. The fruit size at which increases in handling time offset increases in pericarp mass varies among bird species due to differences in bill and body size. Decreases in feeding rate due to decreasing numbers of fruits and increasing search time causes reduced profitability and this effect becomes more severe with decreasing fruit size and/or increasing frugivore size. Consequently, as fruit size decreases relative to frugivore size, fruit abundance becomes increasingly important to fruit selection by frugivores. However, while profitability of resources is a function of characteristics of the resources and the organisms, biological interactions can change profitability rankings; resources that may be more profitable in the absence of behavioral interference, exploitation competition, or predation risk can become less profitable in the face of these interactions. The proposed model integrates these interactions to provide predictions of resource selection and these predictions are supported by published studies.

Search time and test anxiety in a visual location task

This study was conducted to investigate whether increasing search time in a visual location task would result in significantly different relationships between worry/emotionality test anxiety component scores and performance. Fifty graduate students were given 3.5 or 8 s to locate seven embedded geometrical figures projected on a screen. Correlation coefficients (anxiety component scores X performance scores) for the two treatment groups were significantly different for the emotionality component, r = − .73 (3.5 s), r = − .06 (8 s), z( r) = 2.8, p < .01; but not for the worry component, r = − .61 (3.5 s), r = − .26 (8 s). Recommendations include further study utilizing actual classroom situations and commercial instructional materials. Tentative recommendations for the production and utilization of instructional materials are provided.

The Returns to Job Search: A Test of Two Models

T HEORETICAL work on job search views unemployment as productive search activity. By remaining unemployed, a worker acquires labor market information that helps him/ her maximize lifetime utility. Different models have different predictions with regard to the relation between search time and the resulting wage. For example, under one set of assumptions, the expected resulting wage may increase with increasing search time, while under a different set of assumptions, the relationship may be negative. These two possibilities imply differing relationships of the job searcher to the labor market. In the first case (increasing expected resulting wage), the worker weighs a typical offer against the high probability that a better one will come along later. In the second case (decreasing expected resulting wage), because future offers are likely to be worse than the typical present offer, the worker is more likely than otherwise to take whatever job is available. This paper estimates the relationship between search time and resulting wage. A simultaneous equations framework is used in which search time is endogenous (as well as the resulting wage). It is found that the expected resulting wage declines as search time increases. This result is consistent with the ranking by a searcher of firms according to expected wage offers, with the high wage firms sampled first (Salop, 1973). Further, the determinants of the duration of unemployment are investigated by race-sex groups.

The effects of bilateral frontal eye-field, posterior parietal or superior collicular lesions on visual search in the rhesus monkey

Superior collicular, frontal eye-field and posterior parietal lesions increased the time taken to find a circular target among other geometrical shapes. The collicular monkeys were considerably more impaired than the other groups, suggesting that the superior colliculus is the main neural structural underlying this highly practised visual search task. Failure to respond in the 5 sec allowed on each trial increased for all groups, and the collicular and frontal groups showed a small increase in false positive errors. None of the groups increased search time for a near-threshold target on a homogeneous background. Analysis of the latencies of individual trials suggests that scanpaths over the display were still systematic after the lesions. This suggests that the search was being slowed down either by the need to make more correction saccades to five accurate fixations of the stimuli being discriminated, or by an increase in latencies specifically for those saccades that shift the gaze between stimuli.

Optimal allocation of time in resource harvesting

A mathematical model is developed to determine the optimal allocation of time in resource harvesting. Particular emphasis is placed on the influence of search time and competition on optimal niche width. Increased search time and intraspecific competition are shown to favor broader niches. Increased interspecific competition places opposing demands on a species, favoring broader niches due to increased search time and narrower niches to overcome diffuse competition.

A developmental study of visual search behavior

Children in second, fourth and sixth grades and college sophomores were compared on a visual search and scanning task under three experimental conditions. In Condition I, a single target letter was sought in a list of letters of low visual confusability. In Condition II, two target letters were sought but only one appeared in a given list. In Condition III, a single target letter was sought in a list of letters of high confusability. Search time decreased with age in all three tasks. Searching for two targets was no harder than searching for one. A highly confusable visual context increased search time at all age levels.

A developmental study of visual search behavior

Children in second, fourth and sixth grades and college sophomores were compared on a visual search and scanning task under three experimental condilions. In Condition I, a single target letter was sought in a list of letters of low visual confusability. In Condition II, two target letters were sought but only one appeared in a given list. In Condition III, a single target letter was sought in a list of letters of high confusability. Search time decreased with age in all three tasks. Searching for two targets was no harder than searching for one. A highly confusable visual context increased search time at all age levels.