Motivated to retrieve: How often are you willing to go back to the well when the well is dry?

Despite the necessity of the decision to terminate memory search in many real-world memory tasks, little experimental work has investigated the underlying processes. In this study, the authors investigated termination decisions in free recall by providing participants an open-ended retrieval interval and requiring them to press a stop button when they had finished retrieving. Three variables important to assessing one's willingness to search memory were examined: (a) the time spent searching memory after the last successful retrieval before choosing to quit (the exit latency); (b) task difficulty; and (c) individual differences in motivation, as measured by Webster and Kruglanski's (1994) Need for Closure Scale. A strong negative correlation was found between individual differences in motivation and participants' exit latencies. This negative correlation was present only when the retrieval task started out as relatively difficult. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conceptual distinctiveness supports detailed visual long-term memory for real-world objects.

Humans have a massive capacity to store detailed information in visual long-term memory. The present studies explored the fidelity of these visual long-term memory representations and examined how conceptual and perceptual features of object categories support this capacity. Observers viewed 2,800 object images with a different number of exemplars presented from each category. At test, observers indicated which of 2 exemplars they had previously studied. Memory performance was high and remained quite high (82% accuracy) with 16 exemplars from a category in memory, demonstrating a large memory capacity for object exemplars. However, memory performance decreased as more exemplars were held in memory, implying systematic categorical interference. Object categories with conceptually distinctive exemplars showed less interference in memory as the number of exemplars increased. Interference in memory was not predicted by the perceptual distinctiveness of exemplars from an object category, though these perceptual measures predicted visual search rates for an object target among exemplars. These data provide evidence that observers' capacity to remember visual information in long-term memory depends more on conceptual structure than perceptual distinctiveness. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The relation between feelings of knowing and the number of neighboring concepts linked to the test cue

We investigated whether feeling-of-knowing judgments are influenced by the number of different neighboring concepts linked to the test cue in long-term memory as measured using association norms. The purpose was to evaluate contrasting predictions made by the partial-retrieval hypothesis and the competition hypothesis. The partial-retrieval hypothesis assumes the more neighboring concepts activated by the test cue, the higher the feeling of knowing. In contrast, the competition hypothesis assumes that feelings of knowing are sensitive to competition between neighboring concepts, and it predicts that the fewer neighboring concepts activated by the cue, the higher the feeling of knowing. The findings were compatible with the competition hypothesis showing that both feeling-of-knowing and prediction-of-knowing ratings always were higher, the fewer different concepts were linked to the test cue. We obtained an identical pattern of results using different kinds of cues including taxonomic category names, ending sounds, and meaningfully related associates. We consider different ways that these findings could be reconciled with the partial-retrieval hypothesis, and we also discuss implications for other explanations of feeling-of-knowing effects.     

Relative use of necessity and sufficiency information in causal judgments about natural categories.

Participants in 4 studies placed less emphasis on necessity information (instances when the event occurred but the target factor was absent) than sufficiency information (instances when the target factor was present but the event did not occur) when the target factor corresponded to a natural kind category (e.g., race or species) in comparison with an artificial category (e.g., preferences or facial features) or an artifactual category (e.g., product type). Results were not due to differences in familiarity, prior causal beliefs, or ease of imagining the class of instances, but instead derived from less willingness to search for alternative explanations when the target explanation was based on a natural kind category in comparison with artificial or artifactual categories. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual Search and the Collapse of Categorization.

Categorization researchers typically present single objects to be categorized. But real-world categorization often involves object recognition within complex scenes. It is unknown how the processes of categorization stand up to visual complexity or why they fail facing it. The authors filled this research gap by blending the categorization and visual-search paradigms into a visual-search and categorization task in which participants searched for members of target categories in complex displays. Participants have enormous difficulty in this task. Despite intensive and ongoing category training, they detect targets at near-chance levels unless displays are extremely simple or target categories extremely focused. These results, discussed from the perspectives of categorization and visual search, might illuminate societally important instances of visual search (e.g., diagnostic medical screening). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental differences in the memory search of categorized lists.

16 right-handed female 3rd and 6th graders were tested in a recognition memory task with short lists of items from 1 or 2 categories. Latency data for 1-category lists of letters or digits were consistent with a serial-exhaustive model of memory search for both groups. It was also found that the younger Ss searched these lists more slowly. For 2-category lists, developmental differences were found in Ss' ability to use the category information to facilitate information retrieval. Although the category information was very salient for Ss of both ages, only the 6th graders were able to use it to modify their memory search. It was noted that the 6th graders' 2-category data were consistent with a particular nonexhaustive search strategy, the random entry model, which has previously been identified by M. J. Naus et al (see record 1973-06031-001) for adult Ss. The similarity of the 3rd graders' memory search for 1- and 2-category lists suggests that young children do not systematically use information that they have available in permanent memory to facilitate their performance in memory search. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Counterfactual Thinking and the First Instinct Fallacy.

Most people believe that they should avoid changing their answer when taking multiple-choice tests. Virtually all research on this topic, however, has suggested that this strategy is ill-founded: Most answer changes are from incorrect to correct, and people who change their answers usually improve their test scores. Why do people believe in this strategy if the data so strongly refute it? The authors argue that the belief is in part a product of counterfactual thinking. Changing an answer when one should have stuck with one's original answer leads to more "if only . . ." self-recriminations than does sticking with one's first instinct when one should have switched. As a consequence, instances of the former are more memorable than instances of the latter. This differential availability provides individuals with compelling (albeit illusory) personal evidence for the wisdom of always following their 1st instinct, with suboptimal test scores the result. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The cost of search for multiple targets: Effects of practice and target similarity.

With the use of X-ray images, performance in the simultaneous search for two target categories was compared with performance in two independent searches, one for each category. In all cases, displays contained one target at most. Dual-target search, for both categories simultaneously, produced a cost in accuracy, although the magnitude of this dual-target cost was affected by the nature of the targets. When target feature sets shared values, accuracy in dual-target search was equivalent to that in the less accurate of the two single-target searches. However, when targets comprised different feature sets, accuracy in dual-target search was lower than in either single-target search. These results held after practice. In conclusion, dual-target search performance depends on the target representations required for search. When combined representations contain conflicting values within the most informative feature dimensions, then there is a cost in performance. When target representations share features, the search can be guided by the common values so that resources are not wasted on irrelevant distractors. The implication is that security screener performance might be improved by specializing in searching for threat categories that share features. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of outcome conflict in dual-task interference.

The traditional explanation for dual-task interference is that tasks compete for scarce processing resources. Another possible explanation is that the outcome of the processing required for one task conflicts with the processing required for the other task (e.g., cross talk). To explore the contribution of outcome conflict to task interference, we manipulated the relatedness of the tasks. In Experiment 1, subjects searched concurrently for names of boys in one channel and names of cities in another channel. Responses were significantly delayed when nontarget on one channel belonged to, or was even just related to, the category designated as the target for the other channel. No comparable effects were found when the tasks were performed in isolation. Thus, the difficulty of the individual tasks is not the only determinant of how much they will interfere when combined, and there must be substantial interactions between processes carrying out the two tasks. In Experiment 2 subjects searched one channel for specific target letters and another channel for specific target digits. The nontargets in a channel were either from the same alphanumeric category as the targets for that channel or from the opposite category (i.e., the category of the targets for the other channel). It was found that although between-category search was more efficient than within-category search in single tasks, it was less efficient in dual tasks. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Where do I go next? Intelligent searching by very young children.

A memory-based search task was used to investigate the organization of searching by 24 young children. The task required Ss to remember in what natural location a toy had been hidden. Both an older (25–30 mo of age) and a younger (18–23 mo of age) group of Ss achieved a high level of errorless retrievals. To examine Ss' ability to search differentially as a function of their own level of certainty that they remembered the location of the toy, 2 surprise trials were included in which the toy was hidden as usual but was then moved without the S's knowledge. Ss' search behavior on these surprise trials was compared to their error trials. Both age groups showed greater persistence in their initial search on surprise than on error trials, indicating that their retrieval effort was based on their level of subjective certainty. The 2 age groups displayed different patterns in the subsequent searching that they did: The older, but not the younger, Ss searched differently on surprise and error trials. On surprise trials they searched selectively and intelligently, confining their search primarily to locations that were nearby or in some way related to the place where the toy had actually been hidden. The related searching of the older Ss suggests that they had made intelligent guesses about plausible alternative locations for the missing toy. Data provide evidence of early manifestations of metamemory. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The magnitude of binocular disparity modulates search time for targets defined by a conjunction of depth and colour.

Nakayama and Silverman (1986) proposed that, when searching for a target defined by a conjunction of color and stereoscopic depth, observers partition 3D space into separate depth planes and then rapidly search each such plane in turn, thereby turning a conjunctive search into a "feature" search. In their study, they found, consistent with their hypothesis, shallow search slopes when searching depth planes separated by large binocular disparities. Here, the authors investigated whether the search slope depends upon the extent of the stereoscopically induced separation between the planes to be searched (i.e., upon the magnitude of the binocular disparity. The obtained slope shows that (1) a rapid search only occurs with disparities greater than 6 min of arc, a value that vastly exceeds the stereo threshold, and that (2) the steepness of this slope increases in a major way at lower disparities. The ability to implement the search mode envisaged by Nakayama and Silverman is thus clearly limited to large disparities; less efficient search strategies are mandated by lower disparity values, as under such conditions items from one depth plane may be more likely to "intrude" upon the other. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The congruency effect: Just what is being learned?

G. H. Bower, S. Thompson-Schill, and E. Tulving (1994) found that when stimulus-response sets in A–B, A–C learning belong to unique categories (congruent-triads), learning appropriate responses appear rapid and memory performance on a modified modified free recall (MMFR) test is enhanced. Bower et al. assumed that category cues protect associations from interpair interference, allowing more rapid learning. However, unlike arbitrary pairs, congruent pairs also allow a reliance on preexperimental associations. As a result, MMFR test performance may not be an unbiased test of what was learned. In the present experiment, free recall (FR) demonstrated that responses were learned approximately equally in all conditions and that the pattern of clustering was compatible with the hypothesis that preexperimental associations continue to play a major role in FR test performance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Available but unattended conceptual information in working memory: Temporarily active semantic content or persistent memory for prior operations?

In 2 experiments, the authors investigated available but unattended information following working memory task demands. The experimental task presented a memory set containing exemplars from 2 conceptual categories. Following instructions to focus attention on only 1 category, priming of both categories was assessed with category comparisons of exemplar pairs. Priming was greatest for the focused category and for exemplars from the memory set (direct priming). Priming also extended to new exemplars of both categories (indirect priming) and showed little decline over more than 1 min of intervening processes. Finally, changing between category exemplars and features across memory set and comparison phases eliminated the indirect priming. These results support a persistent, operation-specific, procedural account of available but unattended conceptual information in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Distinctiveness and repetition in item recognition.

We scrutinized the hypothesis that the distinctiveness of unrepeated stimuli yields an enhancement of their memorability, when contrasted with repeated stimuli. In three conditions of a variant of von Restorff's (1933) isolation paradigm, unrepeated stimuli were respectively rendered either distinctive, by intermixing them with repeated stimuli from a different category, or nondistinctive, by having both unrepeated and repeated items originate in the same category or categories. The recognition-memory strength difference between unrepeated and repeated stimuli, in terms of a signal-detection measure of sensitivity, was less when the unrepeated stimuli were distinctive than when they were not distinctive. This implies that the relative weakness of unrepeated stimuli may be offset by distinctiveness that accrues from their infrequency. These findings are considered with reference to contemporary theoretical treatments of distinctiveness. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Feeling of knowing in episodic memory following moderate to severe closed-head injury.

The ability to accurately monitor one's memory is a metacognitive process that is important in everyday life. The authors examined episodic memory feeling-of-knowing (FOK) ratings in 21 moderate to severe closed-head injury (CHI) participants (more than 1 year postinjury) and 21 controls. Participants studied 36 critical cue-target word pairs. Following a brief delay, they were asked to recall the target that corresponded to a given cue. Confidence ratings were made for recalled words, and FOK judgments were made for nonrecalled words in terms of the likelihood of recognizing the target word on a subsequent recognition test. CHI participants demonstrated less accurate recall but accurate ability to judge their recall performance (retrospective memory monitoring). They also demonstrated intact FOK judgments when providing binary judgments but demonstrated difficulties making finer discriminations on an ordinal scale (prospective memory monitoring). These findings suggest that memory monitoring is not a unitary construct. It is proposed that CHI participants may display intact memory monitoring when predictions are based on familiarity assessment but not when continued probing for additional episodic information is required. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

FASTPAT: a fast and efficient algorithm for string searching in DNA sequences

A new string searching algorithm is presented aimed at searching for the occurrence of character patterns in longer character texts. The algorithm, specifically designed for nucleic acid sequence data, is essentially derived from the Boyer-Moore method (Comm. ACM, 20, 762-772, 1977). Both pattern and text data are compressed so that the natural 4-letter alphabet of nucleic acid sequences is considerably enlarged. The string search starts from the last character of the pattern and proceeds in large jumps through the text to be searched. The data compression and searching algorithm allows one to avoid searching for patterns not present in the text as well as to inspect, for each pattern, all text characters until the exact match with the text is found. These considerations are supported by empirical evidence and comparisons with other methods.     

Remembering Can Cause Inhibition: Retrieval-Induced Inhibition as Cue Independent Process.

Previous experiments have mostly relied on recall as a dependent measure to assess whether retrieval of information from memory causes inhibition of related information. This study aimed to measure this inhibition in a more direct way. In Experiment 1, it was shown that repeated retrieval of exemplars from a category resulted in longer recognition latencies to nonretrieved exemplars from that same category, compared with recognition latencies to control exemplars. Experiment 2 obtained the same pattern of results using a lexical decision task. This was the 1st time that retrieval-induced forgetting was demonstrated on an implicit test of memory. To exclude noninhibitory explanations of the data, the exemplars were presented in both experiments without their categories as cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the nature of the decision axis in signal-detection-based models of recognition memory.

Most models of recognition memory involve a signal-detection component in which a criterion is placed along a decision axis. Older models generally assume a familiarity-decision axis, but newer models often assume a likelihood ratio axis instead because it allows for a more natural account of the ubiquitous mirror effect. In 3 experiments reported here, item strength was differentially manipulated to see whether a mirror effect would occur. Within a list, the items from 1 category were strengthened by repetition, but the items from another category were not. On the subsequent recognition test, the hit rate was higher for the strong category, but the false-alarm rates for the weak and strong categories were the same (i.e., no mirror effect was observed). This result suggests that the decision axis represents a familiarity scale and that participants adopt a single decision criterion that they maintain throughout the recognition test. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

To calculate or not to calculate: A source activation confusion model of problem familiarity's role in strategy selection.

How do people decide whether to try to retrieve an answer to a problem or to compute the answer by some other means? The authors report 2 experiments showing that this decision is based on problem familiarity rather than on retrievability of some answer (correct or incorrect), even when problem familiarization occurred 24 hr earlier. These effects at the level of the individual problem solver and the results reported by L. M. Reder and F. E. Ritter (see record 1992-30097-001) are well fit with the same parameter values in a spreading-activation computational model of feeling of knowing in which decisions to retrieve or compute an answer are based on the familiarity or activation levels of the problem representation. The authors therefore argue that strategy selection is governed by a familiarity-based feeling-of-knowing process rather than by a process that uses the availability of the answer or some form of race between retrieving and computing the answer. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Changes in the classification of carcinogenic chemicals in the work area. (Section III of the German List of MAK and BAT values)

Carcinogenic chemicals in the work area were previously classified into three categories in section III of the German List of MAK and BAT values (the list of values on maximum workplace concentrations and biological tolerance for occupational exposures). This classification was based on qualitative criteria and reflected essentially the weight of evidence available for judging the carcinogenic potential of the chemicals. In the new classification scheme the former sections IIIA1, IIIA2, and IIIB are retained as categories 1, 2, and 3, to correspond with European Union regulations. On the basis of our advancing knowledge of reaction mechanisms and the potency of carcinogens, these three categories are supplemented with two additional categories. The essential feature of substances classified in the new categories is that exposure to these chemicals does not contribute significantly to the risk of cancer to man, provided that an appropriate exposure limit (MAK value) is observed. Chemicals known to act typically by non-genotoxic mechanisms, and for which information is available that allows evaluation of the effects of low-dose exposures, are classified in category 4. Genotoxic chemicals for which low carcinogenic potency can be expected on the basis of dose/response relationships and toxicokinetics and for which risk at low doses can be assessed are classified in category 5. The basis for a better differentiation of carcinogens is discussed, the new categories are defined, and possible criteria for classification are described. Examples for category 4 (1,4-dioxane) and category 5 (styrene) are presented.