Cognitive skill acquisition and transfer in younger and older adults.

The acquisition of cognitive skills often depends on 1 of (or a combination of) 2 processes, the execution of an algorithm, and the retrieval of problem instances. This study examined the effects of age and repetition of problem instances on the production and verification of solutions to 2 serially presented sets of alphabet arithmetic problems. Analyses of the parameters derived from power-function fits for individuals revealed age differences favoring young adults in improvement span, learning rate, and asymptote. For both age groups, the beneficial effects of repetitions on 1st-set response times were attributable to algorithmic speedup and to the retrieval of instances, whereas improvements in the speed of 2nd-set response times were attributable primarily to item retrieval. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences in strategic behavior during a computation-based skill acquisition task.

The authors evaluated mechanistic and metacognitive accounts of age differences in strategy transitions during skill acquisition. Old and young participants were trained on a task involving a shift from performing a novel arithmetic algorithm to responding via associative recognition of equation–solution pairings. The strategy shift was manipulated by task instructions that either (a) equally focused on speed and accuracy, (b) encouraged retrieval use as a method toward fast responding, or (c) offered monetary incentives for fast retrieval-based performance. Monetary incentives produced a more rapid shift to retrieval relative to standard instructions; older adults showed a greater incentives effect on retrieval use than younger adults. Monetary incentives encouraged retrieval use and response time improvements despite accuracy costs (a speed–accuracy tradeoff). The pattern of results suggested a role of metacognitive and volitional factors in retrieval shift, indicating that an associative learning deficit cannot fully account for older adults’ delayed strategy shift. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age differences and similarities in the shift from computation to retrieval during reading comprehension.

Previous research has established that 1 mechanism underlying speed-ups in task performance with practice involves a shift from computational processing to retrieval of information encoded earlier in practice. To what extent do young and older adults differ in shifts from computation to retrieval with practice in reading comprehension? Young and older adults read short stories containing an unfamiliar noun–noun combination (e.g., bee caterpillar) followed by disambiguating information indicating the combination’s meaning (either the normatively dominant meaning or an alternative subordinate meaning). Stories were presented either once or repeatedly across practice blocks. In Experiment 1, both age groups shifted from computation to retrieval with practice for the repeated items. However, older adults were slower to shift (e.g., older adults showed slower convergence of reading times for repeated subordinate and dominant items). Results of Experiment 2 suggested that the slower shift was due to age differences in bias against using retrieval rather than associative learning differences. The authors compare age differences in retrieval shifts in reading versus other tasks and discuss implications for age differences in the regulation of reading comprehension. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The estimation of marshland degradation in southern Iraq using multitemporal Landsat TM images

Characterization of the marshlands of southern Iraq using Landsat TM data enabled an estimation of the rate at which disruption of water supply has led to the collapse of the ecosystem. Image classification techniques were used to estimate vegetation distribution using an NDVI image, and the areal coverage of water, using bands 1 to 5 of the TM. The Al Amarah marsh to the north of the Euphrates River has seen a reduction of 90 per cent in its areal extent between 1992 and 1994. South of the Euphrates river the Hawr al Hammar marsh has undergone a similar reduction in areal extent between 1992 and 1994, but the collapse of vegetation occurred predominantly between 1993 and 1994. Vegetation collapse appears to be linked to the completion of drainage projects that prevent the influx of nutrient rich spring flood waters to the marshes. East of the Tigris river, the Hawr al Hawizah marsh was observed to have undergone a decline of 40 per cent in the amount of vegetation present between 1992 and 1994. Inundation northwest of a series of barrages around the northern perimeter of the Hawr al Hawizah marsh in 1993 and 1994 suggests that disruption of the influx of water from the Nahr al Musharrah river is the cause of vegetation decline.     

Age differences in memory retrieval shift: Governed by feeling-of-knowing?

The noun-pair lookup (NP) task was used to evaluate strategic shift from visual scanning to retrieval. We investigated whether age differences in feeling-of-knowing (FOK) account for older adults' delayed retrieval shift. Participants were randomly assigned to one of three conditions: (1) standard NP learning, (2) fast binary FOK judgments, or (3) Choice, where participants had to choose in advance whether to see the look-up table or respond from memory. We found small age differences in FOK magnitudes but major age differences in memory retrieval choices that mirrored retrieval use in the standard NP task. Older adults showed lower resolution in their confidence judgments (CJs) for recognition memory tests on the NP items, and this difference appeared to influence rates of retrieval shift, given that retrieval use was correlated with CJ magnitudes in both age groups. Older adults had particular difficulty with accuracy and confidence for rearranged pairs, relative to intact pairs. Older adults' slowed retrieval shift appears to be attributable to (1) impaired associative learning early in practice, not just a lower FOK; but also (2) retrieval reluctance later in practice after the degree of associative learning would afford memory-based responding. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Older adults' use of metacognitive knowledge in source monitoring: Spared monitoring but impaired control.

While episodic memory declines with age, metacognitive monitoring is spared. The current study explored whether older adults can use their preserved metacognitive knowledge to make source guesses in the absence of source memory. Through repetition, words from two sources (italic vs. bold text type) differed in memorability. There were no age differences in monitoring this difference despite an age difference in memory. Older adults used their metacognitive knowledge to make source guesses but showed a deficit in varying their source guessing based on word recognition. Therefore, older adults may not fully benefit from metacognitive knowledge about sources in source monitoring. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Distinguishing Age Differences in Knowledge, Strategy Use, and Confidence During Strategic Skill Acquisition.

The authors examined how age differences in strategy selection are related to associative learning deficits and metacognitive variables, including memory ability confidence. In Experiment 1, increases in memory reliance for performance of the noun-pair lookup task were compared with increases in noun-pair memory ability. In Experiment 2, memory reliance was assessed for noun pairs memorized prior to the task. In each experiment, older adults manifested a substantial delay in transition to a retrieval-based strategy despite comparable noun-pair knowledge. In Experiment 3, young and older adults reported comparable confidence ratings for the accuracy of each memory probe response. However, older adults reported lower confidence in their general ability to use the memory retrieval strategy, which correlated with avoidance of the retrieval strategy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does a time-monitoring deficit influence older adults' delayed retrieval shift during skill acquisition?

The authors evaluated age-related time-monitoring deficits and their contribution to older adults' reluctance to shift to memory retrieval in the noun-pair lookup (NP) task. Older adults (M = 67 years) showed slower rates of response time (RT) improvements than younger adults (M = 19 years), because of a delayed strategy shift. Older adults estimated scanning latencies as being faster than they actually were and showed poor resolution in discriminating short from long RTs early in practice. The difference in estimated RT for retrieval and scanning strategies predicted retrieval use, independent of actual RT differences. Separate scanning and recognition memory tasks revealed larger time-monitoring differences for older adults than in the NP task. Apparently, the context of heterogeneous RTs as a result of strategy use in the NP task improved older adults' accuracy of RT estimates. RT feedback had complex effects on time-monitoring accuracy, although it generally improved absolute and relative accuracy of RT estimates. Feedback caused older adults to shift more rapidly to the retrieval strategy in the NP task. Results suggest that deficient time monitoring plays a role in older adults' delayed retrieval shift, although other factors (e.g., confidence in the retrieval strategy) also play a role. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solidification study of Cu-based alloys obtained by continuous casting

Commercial production of copper by continuous casting in a wheel-and-band machine, with suitable modifications to induce high undercooling, is considered. Impurities control to a large extent the microstructure and mechanical properties of the ingot. Suitable solute additives in the molten alloy to achieve constitutional supercooling during solidification have been analyzed, with particular emphasis on the presence of lead. Experimental information on the Cu-O-Pb phase diagram has been revised and modeling of the microstructure evolution as a function of several casting parameters is being presented.     

Metacognitive influences on study time allocation in an associative recognition task: An analysis of adult age differences.

The current study evaluated a metacognitive account of study time allocation, which argues that metacognitive monitoring of recognition test accuracy and latency influences subsequent strategic control and regulation. The authors examined judgments of learning (JOLs), recognition test confidence judgments (CJs), and subjective response time (RT) judgments by younger and older adults in an associative recognition task involving 2 study–test phases, with self-paced study in Phase 2. Multilevel regression analyses assessed the degree to which age and metacognitive variables predicted Phase 2 study time independent of actual test accuracy and RT. Outcomes supported the metacognitive account—JOLs and CJs predicted study time independent of recognition accuracy. For older adults with errant RT judgments, subjective retrieval fluency influenced response confidence as well as (mediated through confidence) subsequent study time allocation. Older adults studied items that had been assigned lower CJs longer, suggesting no age deficit in using memory monitoring to control learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)