Searching for conjunctively defined targets

It has recently been proposed that in searching for a target defined as a conjunction of two or more separable features, attention must be paid serially to each stimulus in a display. Support for this comes from studies in which subjects searched for a target that shared a single feature with each of two different kinds of distractor items (e.g., a red O in a field of black Os and red Ns). Reaction time increased linearly with display size. We argue that this design may obscure evidence of selectivity in search. In an experiment in which the numbers of the two distractors were unconfounded, we find evidence that subjects can search through specified subsets of stimuli. For example, subjects told to search through just the Os to find the red O target do so without searching through Ns. Implications of selective search are discussed.     

Searching for targets: The effects of specific practice

This study contrasts the effects of specific practice vs nonspecific practice in scanning for sets of five-letter targets. Ss were required to search for new targets after extended practice with one specific target set. Simultaneous memory search was not supported, since searching for one item remained faster than for several items. Serial exhaustive memory search was not supported since the search data were nonlinear. There is evidence that the categorization of a target, even after large amounts of specific practice, is not heavily dependent upon its physical features. A strategy change was detected during practice which allowed more efficient search. It is concluded that a single memory search process can account for the data under both high and low levels of specific practice.     

Affecting speed and accuracy in perception

An account of affective modulations in perceptual speed and accuracy (ASAP: Affecting Speed and Accuracy in Perception) is proposed and tested. This account assumes an emotion-induced inhibitory interaction between parallel channels in the visual system that modulates the onset latencies and response durations of visual signals. By trading off speed and accuracy between channels, this mechanism achieves (a) fast visuo-motor responding to course-grained information, and (b) accurate visuo-attentional selection of fine-grained information. ASAP gives a functional account of previously counterintuitive findings, and may be useful for explaining affective influences in both featural-level single-stimulus tasks and object-level multistimulus tasks.     

The accuracy and speed of repeated responses

Summary Although experimental psychologists measure the quality of performance in terms of either terminal accuracy or latency, no clear theoretical link has been recently made between these measurements. This paper reports two experiments which show that a fundamental limitation to performance, either in terms of speed or accuracy, is the delay since a previous movement was made. Under circumstances where eye-movements are controlled, the ensemble size appears not to affect response latency directly, but response-to-stimulus interval (RSI) has a highly significant effect. Furthermore, the accuracy of responses is independent of either ensemble size or entropy, but is again directly related to RSI. These results are discussed in terms of the instability and lability of the spatial information upon which the operator must act, and it is hypothesized that a major contributing factor to performance in serial tasks is the state of the subject's knowledge about the spaces he or she operates in.     

Models for the statistics and mechanisms of response speed and accuracy

Van Breukelen offers a promising method for modeling both response speed and response accuracy. However, the underlying conception of both dependent measures is somewhat flawed, leading the author to conclude that the approach possesses limitations that, under revised assumptions, may not hold. The central misconception, and a set of related misconceptions, is addressed, and it is suggested that this approach holds a good deal of promise for application in the perceptual and cognitive sciences.     

Searching for salvation: An analysis of US religious searching on the World Wide Web

The goals of this research were to answer three questions. How predominant is religious searching online? How do people interact with Web search engines when searching for religious information? How effective are these interactions in locating relevant information? Specifically, referring to a US demographic, we analyzed five data sets from Web search engine, collected between 1997 and 2005, of over a million queries each in order to investigate religious searching on the Web. Results point to four key findings. First, there is no evidence of a decrease in religious Web-searching behaviors. Religious interest is a persistent topic of Web searching. Second, those seeking religious information on the Web are becoming slightly more interactive in their searching. Third, there is no evidence for a move away from mainstream religions toward non-mainstream religions since the majority of the search terms are associated with established religions. Fourth, our work does not support the hypothesis that traditional religious affiliation is associated with lower adoption of or sophistication with technology. These factors point to the Web as a potentially usefully communication medium for a variety of religious organizations.     

Independence of speed and accuracy in visual search: evidence for separate mechanisms.

Data from two studies that tested children's attention using visual search for a series of targets in a complex display and a sustained-attention task waiting for signals in a similar display were subjected to Factor Analysis to explore previous indications that speed and accuracy (the number of false alarms to nontargets) on this task reflect different mechanisms. The two factors identified confirmed the separation of these two measures and also suggested that the speed factor was related to Mental Age, while the accuracy factor was related to ratings of attentional ability. It is suggested that ratings of attentional ability reflect the efficiency of executive functions, displayed in the ability to inhibit responses to nontargets in these tasks, while speed of search is related to processing speed in the nervous system. Therefore intelligence and attentional ability depend on different underlying features of the nervous system.     

Searching for one versus two identical targets: when visual search has a memory

A recent study has suggested that observers' visual explorations of the external world can proceed unimpaired when the visual environment precludes the operation of memory processes (as, for instance, when the display elements change locations every 100 ms). One theoretical limitation of this study was that distractors were the only elements that had the potential to be tagged during visual search. The present study sought to clarify the amnesic-search hypothesis by investigating whether memory processes can guide search in other contexts in which targets also have the potential to be tagged. Accordingly, the experimental conditions of the previous study were repeated using a different search task in which observers had to decide whether one target or two were present among a variable number of similar distractors. Under these search conditions, the present findings provided strong evidence that memory processes can guide visual search.     

An analysis of age differences in perceptual speed

Tests of the generalized slowing hypothesis have demonstrated the strong predictive power of tests of perceptual comparison speed in accounting for age differences across a range of cognitive domains. The goals of this study were to determine whether short-term memory (STM) and perceptual demands contribute to age differences on two commonly used tests of perceptual comparison speed, the letter and pattern comparison tests, and to test whether these task components account for unique variance in predicting age differences in working memory and reasoning. Results showed that, after controlling for visual contrast sensitivity and a general slowing factor, age differences increased with increases in both STM load and perceptual degradation. Only STM load, however, accounted for a significant portion of the relationship of age with higher level cognition. We concluded that perceptual comparison tests are dependent on multiple age-sensitive abilities, not all of which are related to age differences in higher level cognition.     

The calculus of dissent: An analysis of terrorists' choice of targets

This article applies formal modeling to study a terrorist group's choice of whether to attack or not, and, in the case of an attack, which of two potential targets to strike. Each potential target individually takes protective measures that influence the terrorists' perceived success and failure, and, hence, the likelihood of attack. For domestic terrorism, a tendency for potential targets to overdeter is indicated. For transnational terrorism, cases of overdeterrence and underdeterrence are identified. We demonstrate that increased information about terrorists' preferences, acquired by the targets, may exacerbate inefficiency when deterrence efforts are not coordinated. In some cases, perfect information may eliminate the existence of a noncooperative solution.Yet the need for improved international cooperation is growing. Terrorism is inherently international in character, so that, paradoxically, the more individual states improve their national measures, the more it becomes attractive for the terrorists to cross frontiers ... (Wilkinson 1986, p. 49)     

Age of acquisition and word frequency: determinants of object-naming speed and accuracy

The combined contributions of word age of acquisition (AoA) and word frequency (rated and objective) to word retrieval speed and accuracy were investigated, using a picture-naming paradigm. Results from two fully factorial studies revealed that both AoA and word frequency reliably facilitate the speed and accuracy of word retrieval. Furthermore, word frequency and AoA interacted across delay (0, 750, 1,500, and 2,250 msec) in Experiment 2. This resulted in word frequency's playing a stronger role for late-acquired words across delays. It is concluded that both AoA and word frequency play a fundamental role in lexical retrieval. The results are also consistent with the view that both factors affect the same processing stages.     

Searching for politicians: An information-processing approach to face recognition

Previous work on face recognition has concentrated on the processing of unfamiliar faces. This paper examines the recognition of already familiar faces, specifically politicians. Three experiments are described in which the subject's task was to search through a series of faces for particular target politicians. In Experiment I the function relating search time to target set size was found to be negatively accelerated. A similar function was observed when names were used as search items. In Experiment II all subjects searched for four targets, and the relationship between distractors and target items was varied. Distractors rated visually similar to the targets took longer to reject than those rated dissimilar. Distractors who were other politicians took longer to reject than actors, and this effect of semantic category was independent of visual similarity. In Experiment III, where subjects searched for a single target, semantic category appeared only to have an effect when the distractors were also visually similar to the target. Models of the rejection process are discussed, and the similarities between the effects observed here, with faces, and those reported elsewhere for words are pointed out.     

Semantic memory retrieval: Analysis by speed accuracy tradeoff functions

Semantic memory retrieval for verifying category--example associations was tested by a speed accuracy tradeoff method: present the category for 2 s, present a correct or incorrect example followed, after a variable lag (0, 0.1, 0.2, 0.3, 0.4, 0.6, 0.8, 1, 2, or 3 s), by a signal to make a “yes-no” response in about 0.2 s. Although the strength of the category--example association is higher for high dominance examples of a category, retrieval dynamics did not vary with dominance level. Recognition for category--example associations appears to be a direct-access (parallel) retrieval process. Priming a category by repeated testing of the same category over three consecutive trials had no effect on either asymptotic strength or retrieval dynamics. Partitioning into short, medium, and long latency responses at each lag produced microtradeoff functions which did not lie on the same macrotradeoff function. Retrieval dynamics were invariant with long-term practice.     

Combining speed and accuracy to assess error-free cognitive processes

Both the speed and accuracy of responding are important measures of performance. A well-known interpretive difficulty is that participants may differ in their strategy, trading speed for accuracy, with no change in underlying competence. Another difficulty arises when participants respond slowly and inaccurately (rather than quickly but inaccurately), e.g., due to a lapse of attention. We introduce an approach that combines response time and accuracy information and addresses both situations. The modeling framework assumes two latent competing processes. The first, the error-free process, always produces correct responses. The second, the guessing process, results in all observed errors and some of the correct responses (but does so via non-specific processes, e.g., guessing in compliance with instructions to respond on each trial). Inferential summaries of the speed of the error-free process provide a principled assessment of cognitive performance reducing the influences of both fast and slow guesses. Likelihood analysis is discussed for the basic model and extensions. The approach is applied to a data set on response times in a working memory test. The authors wish to thank Roger Ratcliff, Christopher Chabris, and three anonymous referees for their helpful comments, and Aureliu Lavric for providing the data analyzed in this paper.     

The speed and accuracy of material recognition in natural images

We studied the time course of material categorization in natural images relative to superordinate and basic-level object categorization, using a backward-masking paradigm. We manipulated several low-level features of the images—including luminance, contrast, and color—to assess their potential contributions. The results showed that the speed of material categorization was roughly comparable to the speed of basic-level object categorization, but slower than that of superordinate object categorization. The performance seemed to be crucially mediated by low-level factors, with color leading to a solid increase in performance for material categorization. At longer presentation durations, material categorization was less accurate than both types of object categorization. Taken together, our results show that material categorization can be as fast as basic-level object categorization, but is less accurate.     

Effects of prolonged work on data entry speed and accuracy

In 2 experiments, participants used a keyboard to enter 4-digit numbers presented on a computer monitor under conditions promoting fatigue. In Experiment 1, accuracy of data entry declined but response times improved over time, reflecting an increasing speed-accuracy trade-off. In Experiment 2, the (largely cognitive) time to enter the initial digit decreased in the 1st half but increased in the 2nd half of the session. Accuracy and time to enter the remaining digits decreased across though not within session halves. The (largely motoric) time to press a concluding keystroke decreased over the session. Thus, through a combination of facilitation and inhibition, prolonged work affects the component cognitive and motoric processes of data entry differentially and at different points in practice.     

Agonistic and antagonistic interaction in speed/accuracy tradeoff: A delta-lognormal perspective

This paper reports the results of a model-based analysis of movements gathered in a 4 × 4 experimental design of speed/accuracy tradeoffs with variable target distances and width. Our study was performed on a large (120 participants) and varied sample (both genders, wide age range, various health conditions). The delta-lognormal equation was used for data modeling to investigate the interaction between the output of the agonist and the antagonist neuromuscular systems. Empirical observations show that the subjects must correlate more tightly the impulse commands sent to both neuromuscular systems in order to achieve good performances as the difficulty of the task increases whereas the correlation in the timing of the neuromuscular action co-varies with the size of the geometrical properties of the task. These new phenomena are discussed under the paradigm provided by the Kinematic Theory and new research hypotheses are proposed for further investigation of the speed/accuracy tradeoffs.