Operation-specific effects of numerical surface form on arithmetic strategy.

Educated adults solve simple addition problems primarily by direct memory retrieval, as opposed to by counting or other procedural strategies, but they report using retrieval substantially less often with problems in written-word format (four + eight) compared with digit format (4 + 8). It was hypothesized that retrieval efficiency is relatively low with word operands compared with digits and that this promotes a shift to procedural backup strategies. Consistent with this hypothesis, Experiment 1 demonstrated greater word-format costs on retrieval usage for addition than subtraction, which was due to increased counting for addition but not subtraction. Experiment 2 demonstrated greater word-format costs on retrieval for division than multiplication, which was due to increased use of multiplication-fact reference to solve division problems. Format-related strategy shifts away from retrieval reflected both the efficiency of retrieval for a given operation and the availability of viable alternative strategies. The results demonstrate that calculation processes are not abstracted away from problem surface form. The authors propose that retrieval efficiency for arithmetic connects diverse performance and strategy-related effects across key arithmetic factors, including arithmetic operation, numerical size, and numeral format. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Context-dependent semantic priming in number naming.

Previous research has shown that time to name single-digit Arabic numbers is about 15 ms slower when naming trials are interleaved with simple multiplication (e.g., state product of 2 × 3) than when naming digits is interleaved with magnitude comparison (e.g., state larger; 2 ↑ 3). To explain this phenomenon, J. I. D. Campbell and A. W. S. Metcalfe (2008) proposed that the comparison context enables both semantic and asemantic pathways for digit naming but that number-fact retrieval inhibits the semantic route and slows digit naming relative to the comparison context. To test this hypothesis, the authors modified the naming context paradigm by introducing a semantic priming manipulation. They replicated the digit-naming response time advantage for comparison relative to the multiplication context and observed semantic priming only in the comparison context. In comparison blocks, digit naming was 8 ms faster immediately after naming near digit primes (±1) compared to far primes (≥3), but in multiplication blocks there was no priming. The results reinforce the theory that number-fact retrieval can inhibit the semantic route for digit naming (L. Cohen & S. Dehaene, 1995) and thereby reconfigure the cognitive architecture for naming digits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interpreting instructional cues in task switching procedures: The role of mediator retrieval.

In 3 experiments the role of mediators in task switching with transparent and nontransparent cues was examined. Subjects switched between magnitude (greater or less than 5) and parity (odd or even) judgments of single digits. A cue-target congruency effect indicated mediator use: subjects responded faster to congruent cue-target combinations (e.g., ODD-3) than to incongruent cue-target combinations (e.g., ODD-4). Experiment 1 revealed significant congruency effects with transparent word cues (ODD, EVEN, HIGH, and LOW) and with relatively transparent letter cues (O, E, H, and L) but not with nontransparent letter cues (D, V, G, and W). Experiment 2 revealed significant congruency effects after subjects who were trained with nontransparent letter cues were informed of the relations between cues and word mediators halfway through the experiment. Experiment 3 showed that congruency effects with relatively transparent letter cues diminished over 10 sessions of practice, suggesting that subjects used mediators less as practice progressed. The results are discussed in terms of the role of mediators in interpreting instructional cues. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adults' strategies for simple addition and multiplication: Verbal self-reports and the operand recognition paradigm.

Accurate measurement of cognitive strategies is important in diverse areas of psychological research. Strategy self-reports are a common measure, but C. Thevenot, M. Fanget, and M. Fayol (2007) proposed a more objective method to distinguish different strategies in the context of mental arithmetic. In their operand recognition paradigm, speed of recognition memory for problem operands after solving a problem indexes strategy (e.g., direct memory retrieval vs. a procedural strategy). Here, in 2 experiments, operand recognition time was the same following simple addition or multiplication, but, consistent with a wide variety of previous research, strategy reports indicated much greater use of procedures (e.g., counting) for addition than multiplication. Operation, problem size (e.g., 2 + 3 vs. 8 + 9), and operand format (digits vs. words) had interactive effects on reported procedure use that were not reflected in recognition performance. Regression analyses suggested that recognition time was influenced at least as much by the relative difficulty of the preceding problem as by the strategy used. The findings indicate that the operand recognition paradigm is not a reliable substitute for strategy reports and highlight the potential impact of difficulty-related carryover effects in sequential cognitive tasks. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Adult age differences in regional cerebral blood flow during visual world identification: evidence from H215O PET

We used H215O PET to investigate adult age differences in regional cerebral blood flow (rCBF) during the performance of a visual word identification task. The study participants were 20 healthy, right-handed men: 10 young adults between 18 and 27 years of age, and 10 older adults between 63 and 75 years of age. The word identification task comprised six blocks of test trials representing four task conditions; subjects responded manually. The task conditions varied with regard to whether semantic retrieval was required (e.g., word/nonword discrimination vs simple response to each stimulus) and with regard to the difficulty of visual encoding (e.g., words presented normally vs words with asterisks inserted between adjacent letters). Each subject performed all six trial blocks, concurrently with each of six H215O PET scans. Analyses of quantitative CBF data obtained from the arterial time-activity curve demonstrated a significant age-related decline in global CBF rate. Analyses of the changes in rCBF between task conditions indicated that retrieval of semantic information sufficient to distinguish words from nonwords is mediated by a ventral occipitotemporal cortical pathway. Specific areas within this pathway were also associated with visual encoding processes. Several rCBF activations were significantly greater for young adults than for older adults, indicating an age-related decline in processing efficiency within this ventral occipitotemporal pathway. Although the performance data demonstrated a greater age-related slowing for visual encoding than for semantic retrieval, these age-related performance changes were not associated with corresponding changes in rCBF activation.     

The effect of divided attention on memory for items and their context.

Examined differences between item and context memory using divided attention at encoding and retrieval. Ss, in 3 experiments, were presented with word lists and were instructed to learn the items (i.e., words), the intrinsic context (i.e., the color of the cards on which each word was presented), and the extrinsic context (i.e., the temporal order of the words). In Exp 1 24 undergraduates (aged 20–32 yrs) participated in a digit-monitoring and memory tasks. In Exp 2 the authors examined the effect of divided attention at retrieval using 24 undergraduates (aged 18–29 yrs). In Exp 3 the authors examined memory performance when divided attention was employed at encoding on all lists, and attentional load was manipulated at retrieval using 24 undergraduates (aged 19–32 yrs). Among young adults, in comparison to conditions of full attention, divided attention applied at encoding only or retrieval only resulted in equally lower performance on all memory tasks; in contrast, divided attention applied at both encoding and retrieval resulted in lower performance only on memory for temporal order. The findings support the idea that memory for temporal order requires greater attentional resources and strategic processing than memory for items. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Priming by numb3r5 does not involve top-down feedback.

Using the same–different task, Perea, Du?abeitia, Pollatsek, and Carreiras (2009) showed that digits resembling letters (“leet digits”; e.g., 1 = I, 4 = A) primed pseudoword strings (e.g., V35Z3D–VESZED), but letters resembling digits (“leet letters”) did not prime digit strings (e.g., 9ES7E2–935732), and suggested that this is due to top-down feedback available for letter, but not digit, strings. Here we show that (a) single letters show as much leet priming as 3-letter words (Experiment 1); (b) leet priming is equally robust for digit strings and pseudowords when the string is 4 items long but not when 6 items long (Experiment 2); and (c) with 6-item strings, orthotactically illegal letter strings (e.g., OIAUEQ) behave just like digit strings (Experiment 3). These results indicate that the asymmetry in leet priming is not due to top-down feedback available selectively for letter strings. We offer an alternative explanation based on the Bayesian reader account of masked priming proposed by Norris and Kinoshita (2008), and the role played by the orthotactic knowledge used to extend the functional capacity of visual working memory involved in performing the same–different task. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Guessing strategies, aging, and bias effects in perceptual identification

In the typical single-stimulus perceptual identification task, accuracy is improved by prior study of test words, a repetition priming benefit. There is also a cost, inasmuch as previously studied words are likely to be produced (incorrectly) as responses if the test word is orthographically similar but not identical to a studied word. In two-alternative forced-choice perceptual identification, a test word is flashed and followed by two alternatives, one of which is the correct response. When the two alternatives are orthographically similar, test words identical to previously studied items are identified more accurately than new words (a benefit) but tests words orthographically similar to studied words are identified less accurately than new words (a cost). Ratcliff and McKoon (in press) argue that these are bias effects that arise in the decision stage of word identification. We report five experiments that examined the alternative hypothesis that these bias effects arise from postperceptual guessing strategies. In single-stimulus perceptual identification, repetition priming benefits were equally great for young and older adults who claimed to use deliberate guessing strategies and those who did not (Experiment 1). In contrast, only groups of young and older people who claimed to deliberately guess studied words in a two-alternative forced-choice task (Experiments 2 and 5) showed reliable benefits and costs. Costs and benefits were abolished in the two-alternative forced-choice task when a very long study list was used, presumably because the increased retrieval burden made the use of deliberate guessing strategies less attractive (Experiment 3). Under conditions similar to those of Experiment 3, repetition priming was observed in single-stimulus perceptual identification (Experiment 4). These results are consistent with the view that costs and benefits in the forced-choice perceptual identification task arise from deliberate guessing strategies but that those in the single-stimulus task do not. The possibility that the observed relationship between strategy reports and priming effects reflects erroneous postexperimental assessments of strategies by participants is also considered.     

Long-term priming of neighbours biases the word recognition process: Evidence from a lexical decision task.

The role of orthographically similar words (i.e., neighbours) in the word recognition process has been studied extensively using short-term priming paradigms (e.g., Colombo, 1986). Here we demonstrate that long-term effects of neighbour priming can also be obtained. Experiment 1 showed that prior study of a neighbour (e.g., TANGO) increased later lexical decision performance for similar words (e.g., MANGO), but decreased performance for similar pseudowords (e.g., LANGO). Experiment 2 replicated this bias effect and showed that the increase in lexical decision performance due to neighbour priming is selectively due to words from a relatively sparse neighbourhood. Explanations of the bias effect in terms of lexical activation and episodic memory retrieval are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Adult age differences in storage-retrieval processes: A stages-of-learning analysis of developmental interactions in concreteness effects.

In standard list-learning experiments, Age × Treatment interactions have been regarded as an important source of information regarding the locus (storage/retrieval) of age-related memory deficits in adulthood. Unfortunately, these interactions may be spurious byproducts of the use of fixed-trials designs in which age and completeness of learning are confounded. In this paper, we report two experiments in which these problems were explored in the context of item concreteness effects in young and old adults' free recall. In each experiment, eighty 20-year-olds and forty-two 70-year-olds memorized a 16-item list to a stringent acquisition criterion. The manipulations were pictures versus words (Exp. 1) and concrete versus abstract nouns (Exp. 2). The data were analyzed using a recently developed two-stage model that delivers numerical estimates of the impact of these manipulations on the storage and retrieval components of recall. For Experiment 1, the results showed that: (a) for young adults, pictures were easier to store and retrieve than words; (b) for old adults, there was a pictorial superiority effect at storage but a marked pictorial inferiority effect at retrieval; and (c) although younger adults were better than older adults at storing pictures and words and at retrieving pictures, older adults were better than younger adults at retrieving words. For Experiment 2, the results showed that: (a) on average, concrete words were easier to store and retrieve than abstract words at both age levels; and (b) on average, although younger adults were better than older adults at storing concrete and abstract words and at retrieving abstract words, older adults were better than younger adults at retrieving concrete words. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Echoic memory processes in good and poor readers.

Conducted 4 experiments to determine whether echoic memory plays a role in differences between good and poor readers. In Exp I, with 9 poor (mean age 11.05 yrs) and 9 good (mean age 10.9 yrs) readers, and Exp II, with 12 poor (mean age 10.85 yrs) and 12 good (mean age 10.7 yrs) readers, a suffix procedure was used in which the S was read a list of digits with either a tone control or the word go appended to the list. For lists that exceeded the length of the Ss' memory span by 1 digit (i.e., that avoided ceiling effects), poor readers showed a larger decrement in the suffix condition than did good readers. In Exp III, with 14 poor (mean age 10.64 yrs) and 14 good (mean age 10.83 yrs) readers, Ss shadowed words presented to 1 ear at a rate determined to give 75–85% shadowing accuracy. The item presented to the nonattended ear were words and an occasional digit. At various intervals after the presentation of the digit, a light signaled that the S was to cease shadowing and attempt to recall any digit that had occurred in the nonattended ear recently. Whereas good and poor readers recalled the digit equally if tested immediately after presentation, poor readers showed a faster decline in recall of the digit as retention interval increased. In Exp IV, using Ss from Exp II, bursts of white noise were separated by 9–400 msec of silence, and the S was to say whether there were 1 or 2 sounds presented. There were no differences in detectability functions for good and poor readers. (39 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in mental multiplication: evidence for peripheral but not central decrements

This study reports two mental multiplication experiments that were designed to measure age differences in central and peripheral processes. Experiment 1 varied task type (verification vs production), and Experiment 2 varied exposure duration (presentation until response, 600 ms, and 300 ms) on a production task. Neither experiment showed evidence of age differences in central processes (e.g., retrieval speed); however, there was some evidence of a peripheral-process (e.g., encoding) decrement for older adults. Specifically, there were no Age X Problem Size interactions for either experiment. Experiment 2 revealed decreasing age differences as problem difficulty increased. Indeed, for the 300-ms exposure duration, there were no age differences in RT or error rate. These results suggest that the magnitude of age differences in central processing speed are significantly less extreme than are age differences for peripheral processing speed for this type of mental arithmetic task. Also, older adults, in general, may have a higher skill level for basic fact retrieval in mental arithmetic than do young adults.     

On the temporal dynamics of digit comparison processes.

The authors studied the temporal dynamics of digit comparison processes by presenting the digits with a stimulus onset asynchrony (SOA) of 0, 70, 140, or 210 ms. Experiment 1 used the standard complete paired comparison design that confounds numerical and probabilistic information in the digit presented first. The results showed large effects of SOA that differed characteristically for different digit pairs. These results changed considerably in Experiment 2, using a design that removed any probabilistic contingencies. Experiment 3 examined a form of congruity effect related to the temporal order of the digits. The authors formulated and compared to the data 2 models that differed in their assumptions about the loci of digit-specific and SOA-specific effects: Either the participants use partial numerical advance information to prepare for the suggested response, or they start to process numerical information only after both digits are presented. When probabilistic contingencies were removed, the data favored the latter model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Multiplication by eye and by ear for Chinese-speaking and English-speaking adults.

Under two conditions, 32 English-speaking and 32 Chinese-speaking adults solved single-digit multiplication problems. In one condition, problems were presented as visual digits (e.g., 8×9). In the other condition, problems were presented as auditory number words in the participant's first language (e.g., /eit/ /taimz/ /nain/). Chinese-speaking adults made proportionately more operand-intrusion errors (e.g., 4×8=24) than English-speaking adults. Both groups made more operand-intrusion errors with auditory than with visual presentation. These findings are similar to those found when participants solve problems presented as visual number words (e.g., eight×nine), suggesting that in both cases the activation of phonological codes interferes with processing. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Divided attention and memory: Evidence of substantial interference effects at retrieval and encoding.

In 5 divided attention (DA) experiments, students (24 in each experiment) performed visual distracting tasks (e.g., recognition of words, word and digit monitoring) while either simultaneously encoding an auditory word list or engaging in oral free recall of the target word list. DA during retrieval, using either of the word-based distracting tasks, produced relatively larger interference effects than the digit-monitoring task. DA during encoding produced uniformly large interference effects, regardless of the type of distracting task. Results suggest that when attention is divided at retrieval, interference is created only when the memory and concurrent task compete for access to word-specific representational systems; no such specificity is necessary to create interference at encoding. During encoding, memory and concurrent tasks compete primarily for general resources, whereas during retrieval, they compete primarily for representational systems. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development of word identification speed in skilled and less skilled beginning readers.

Three phases comprise the development of word reading skill: accuracy, automaticity, and speed. The 3rd phase is reached when components of the identification process (i.e., graphic, phonological, semantic) are unitized in memory for particular words. Attainment of this final phase was explored with 2 experiments. In Exp I with Ss from 1st-, 2nd-, and 4th-grade classes, skilled and less skilled readers identified familiar printed words, CVC nonwords, digits, and pictures. Attainment of unitized speeds to printed words was inferred if Ss identified words as rapidly as digits. This level was exhibited by skilled readers in all grades but by less skilled readers only in 4th grade. Unitized speed with CVCs was evident among 2nd- and 4th-grade skilled readers, but not among less skilled readers at any grade. In Exp II, 18 1st-grade and 19 2nd-grade poor readers practiced reading familiar words and CVCs. Practice boosted RTs to CVCs but not to words read accurately before training, and RTs to both remained slower than digit RTs, indicating that practice promotes the development of unitized speeds very slowly in less skilled readers. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Clustering and switching as two components of verbal fluency: Evidence from younger and older healthy adults.

Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Role of generalized and episode specific memories in the word frequency effect in recognition.

Frequency, recency, and type of prior exposure to very low- and high-frequency words were manipulated in a 3-phase (i.e., familiarization training, study, and test) design. Increasing the frequency with which a definition for a very low-frequency word was provided during familiarization facilitated the word's recognition in both yes–no (Experiment 1) and forced-choice paradigms (Experiment 2). Recognition of very low-frequency words not accompanied by a definition during familiarization first increased, then decreased as familiarization frequency increased (Experiment 1). Reasons for these differences were investigated in Experiment 3 using judgments of recency and frequency. Results suggested that prior familiarization of a very low-frequency word with its definition may allow a more adequate episodic representation of the word to be formed during a subsequent study trial. Theoretical implications of these results for current models of memory are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Endothelial cells of the kidney vasa recta express the urea transporter HUT11

Although verbal fluency is a frequently used neuropsychological test, little is known about the underlying cognitive processes. The authors proposed that 2 important components of fluency performance are clustering (i.e., the production of words within semantic or phonemic subcategories) and switching (i.e., the ability to shift between clusters). In Experiment 1, correlational data from 54 older and 41 younger adults indicated that both components were highly correlated with the number of words generated on semantic fluency, whereas switching was more highly correlated than clustering with the number of words generated on phonemic fluency. On semantic fluency, younger participants generated more words and switched more frequently than older participants; on phonemic fluency, older participants produced larger clusters than younger participants. In Experiment 2, among 22 young adults, divided attention decreased the number of words generated and decreased switching on phonemic fluency only. Overall, findings suggest that clustering and switching are dissociable fluency components and that switching is related to frontal-lobe functioning.     

Developmental differences in episodic retrieval: The role of differences in concept representations in semantic memory.

Developmental differences in the relative salience of features in concept representations in semantic memory and their contributions to differences in cued recall were examined in two experiments. For second graders, fifth graders, and college students, acquisition encoding of cue–target noun pair information was constrained by means of defining-, characteristic-, category-, and incidental-feature orienting questions. At retrieval, the encoding of cue information alone was constrained (Experiment 1) within subjects by means of the same (e.g., defining at acquisition and defining at retrieval) or related (e.g., defining at acquisition and characteristic at retrieval) retrieval questions or was unconstrained (Experiment 2). In both experiments, the acquisition presentation duration was manipulated (1 s or 5 s) in order to examine the spread of feature activation within concepts. The results showed that recall varied with feature salience, with the salience greatest for defining features. In addition, the results suggested that the relative salience of defining features was at least as great for the children as for the adults. The results offer no support for Keil and Batterman's (1984) hypothesis of a shift from characteristic to defining features in the development of word meaning representation in memory. (21 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)