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Few studies have compared interference-based forgetting between item versus associative memory. The memory-system dependent forgetting hypothesis (Hardt, Nader, & Nadel, 2013) predicts that effects of interference on associative memory should be minimal because its hippocampal representation allows pattern separation even of highly similar information. In contrast, there should be strong interference effects on extra-hippocampally represented item memory. We tested this prediction in behavioral data from 3 experiments using continuous recognition paradigms. Given older adults' greater deficits in associative than item memory, we also compared younger and older adults to test whether this associative deficit extends to greater interference susceptibility in older adults' associative memory. Experiment 1 examined item-item associative memory with participants studying unrelated word pairs continuously intermixed with item (single words) and associative (intact vs. recombined pairs) recognition tests across interference-filled lags. Experiments 2 and 3 examined item-context (i.e., source) associative memory with participants studying words in different spatial positions continuously intermixed with source-monitoring tests (presented on top vs. on bottom vs. new?) across interference-filled lags (Experiment 3 controlling for delay/decay-based effects). In all experiments, item memory declined from the first lag on. In contrast, associative memory initially remained stable, with strong evidence for null effects of interference even in older adults, but showed some declines at later lags. The data supports Hardt et al.'s proposal of differential interference-based forgetting in item versus associative memory. The results further show that the age-related associative memory deficit does not extend to greater interference-based forgetting in older adults' associative memory. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

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The microstructure, polarity and Si distribution in AlN/GaN layers grown by plasma assisted molecular beam epitaxy (PAMBE) on Si(111) was assessed by scanning transmission electron microscopy (STEM). Samples grown under both metal- and nitrogen-rich conditions contained defects at the AlN/Si interface which suggest formation of an Al-Si eutectic. Correlated with this, interfacial segregation of Si was found in the samples. It is proposed that Si is dissolved in a eutectic layer floating on the AlN surface under metal-rich conditions. This Si is then incorporated into the film if the growth becomes nitrogen-rich, either intentionally or due to plasma source transients. These Si-rich layers appear to induce inversion of the nitride from nitrogen- to metal-polarity, and uncontrolled variations in the Si concentration cause occasional nonuniformity in the resulting inversion.

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The purpose of the current study was to assess whether the age-related associative memory deficit is affected by stereotype threat, which has been shown to negatively affect performance on a wide variety of cognitive tasks, including memory performance of older adults. To date, the effects of stereotype threat on older adults' memory performance have only been shown using tests of item memory, and using only between-subjects manipulations. The first experiment manipulated stereotype threat by providing younger and older adults with either stereotype consistent (threat condition) or stereotype inconsistent (nonthreat condition) information before studying lists of item pairs and being tested for both item and associative memory. The results revealed a triple interaction of Age × Test × Condition (a strong associative memory deficit in the threat condition that disappeared in the nonthreat condition), and this pattern of results was found both between- and within-subjects. A follow-up control experiment also yielded an age-related associative deficit, suggesting that stereotype threat may be activated even under normal testing conditions. These results imply that stereotype threat could affect older adults' associative memory, and that one effective strategy to reduce the associative deficit of older adults is to reverse negative stereotypes that exist. (PsycINFO Database Record

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Older adults show an associative deficit in episodic memory compared to younger adults. Previous research suggests both strategic and automatic binding deficits contribute to older adults' poorer memory performance. Using behavioral manipulations designed to affect strategic and automatic binding of associations, three experiments attempted to simulate an associative deficit in younger adults. In these experiments participants learned face-scene pairs and then were given item and associative recognition memory tests. We manipulated the time allotted at encoding and retrieval to simulate strategic deficits, and the length of the retention interval to simulate automatic deficits. Results indicate that both manipulations separately contribute to a differential decline in associative memory, similar to the one shown by older adults, especially as reflected in the differential increase in false alarm rate in the associative memory test more than in the item memory test. Considerations of possible underlying brain mechanisms are discussed.

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Divided attention (DA) at encoding has been shown to significantly disrupt later memory for the studied information. However, what type of processing gets disrupted during DA remains unresolved. In this study, we assessed the degree to which strategic effortful processes are affected under DA by comparing the effects of DA at encoding under intentional and pure incidental learning instructions. In three experiments, participants studied list of words or word pairs under either full or divided attention. Results of three experiments, which used different methodologies, converged to show that the effects of DA at encoding reduce memory performance to the same degree under incidental and intentional learning. Secondary task performance indicated that encoding under intentional learning instructions was more effortful than under incidental learning instructions. In addition, the results indicated enhanced attention to the initial appearance of the words under both types of learning instructions. Results are interpreted to imply that other processes, rather than only strategic effortful ones, might be affected by DA at encoding.

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We present the homoepitaxial growth of p-type, magnesium doped gallium nitride shells by use of halide vapor phase epitaxy (HVPE) on n-type gallium nitride nanowires grown by plasma-assisted molecular beam epitaxy (MBE). Scanning electron microscopy shows clear dopant contrast between the core and shell of the nanowire. The growth of magnesium doped nanowire shells shows little or no effect on the lattice parameters of the underlying nanowires, as measured by x-ray diffraction (XRD). Photoluminescence measurements of the nanowires show the appearance of sub-bandgap features in the blue and the ultraviolet, indicating the presence of acceptors. Finally, electrical measurements confirm the presence of electrically active holes in the nanowires.