Analysis revealed a tight, functionally appropriate relationship between the flight morphology and foraging ecology of bats on Lombok I., Indonesia, that crossed family-level phylogenetic relationships in some instances.While aspect ratio, wing loading and tip shape were all important in separating microbat foraging strategies on Lombok I., the megabats were arrayed on differences in wing loading and tip shape related to solitary versus colonial foraging strategies. Flight morphology is a useful tool for studying ecological structure in the organisation of megabat as well as microbat communities.
Items that are held in visual working memory can guide attention towards matching features in the environment. Predominant theories propose that to guide attention, a memory item must be internally prioritized and given a special template status, which builds on the assumption that there are qualitatively distinct states in working memory. Here, we propose that no distinct states in working memory are necessary to explain why some items guide attention and others do not. Instead, we propose variations in attentional guidance arise because individual memories naturally vary in their representational fidelity, and only highly accurate memories automatically guide attention. Across a series of experiments and a simulation we show that (1) items in working memory vary naturally in representational fidelity; (2) attention is guided by all well-represented items, though frequently only one item is represented well enough to guide; and (3) no special working memory state for prioritized items is necessary to explain guidance. These findings challenge current models of attentional guidance and working memory and instead support a simpler account for how working memory and attention interact: only the representational fidelity of memories, which varies naturally between items, determines whether and how strongly a memory representation guides attention.
The presence or absence of 61 waterbird species on 95 wetlands in south-western Australia was related to six wetland characteristics: salinity, emergent vegetation, water depth, pH, phosphorus level and wetland size. More species were associated with salinity and vegetation than with other wetland characteristics. There were more positive associations with brackish than with fresh or saline wetlands and few species occurred in hypersaline wetlands. Trees or shrubs and sedges were the vegetation with which most species were associated; few species were recorded on completely open wetlands or those with only samphire. The 95 wetlands were classified into five groups on the basis of waterbird use. All wetland characteristics differed between groups but larger differences occurred in salinity, vegetation and water depth. The wetland group that supported most species also supported the highest numbers of waterbirds and most breeding species.
Critical evaluation of the nutrient requirements of an animal requires the use of a puri®ed reference diet. In this study, the eects of either a puri®ed reference experimental diet, a practical experimental diet and an imported commercial diet on the growth and nutritional condition of the prawn Penaeus monodon were compared. The reference diet, based on widely available ingredients of consistent and known nutrient content, supported excellent prawn growth when fed either ad libitum or subsatiation (» 75% of the mean initial satiation intake). In a 6-week experiment, growth (as percentage increase in weight, SEM) of the prawns fed ad libitum diered signi®cantly (P < 0.05) between each diet in the order: practical (142 10%), reference (121 9%) and commercial (91 16%). Growth for the reference diet fed subsatiation was 116 4%, and was not signi®cantly (P > 0.05) dierent from that obtained with the same diet fed ad libitum. Dry matter food conversion for the reference diet was signi®cantly (P < 0.05) better when fed subsatiation (1.58 0.08) rather than ad libitum (2.08 0.06) and better than that obtained with either the practical (3.40 0.15) or commercial (3.02 0.28) diets, which were not signi®cantly (P > 0.05) dierent from each other. The lipid content (mg g ±1 of prawn) of the digestive gland of prawns fed ad libitum was similar for reference, practical and commercial diets (6.03 0.38, 4.92 0.90 and 4.92 0.95 mg g ±1 of prawn, respectively), but signi®cantly (P < 0.05) higher than that for the reference diet fed subsatiation (4.73 0.38 mg g ±1 of prawn). KEY WORDS
We argue that critical areas of memory research rely on problematic measurement practices and provide concrete suggestions to improve the situation. In particular, we highlight the prevalence of memory studies that use tasks (like the "old/new" task: "have you seen this item before? yes/no") where quantifying performance is deeply dependent on counterfactual reasoning that depends on the (unknowable) distribution of underlying memory signals. As a result of this difficulty, different literatures in memory research (e.g., visual working memory, eyewitness identification, picture memory, etc) have settled on a variety of fundamentally different metrics to get performance measures from such tasks (e.g., A′, corrected hit rate, percent correct, d′, diagnosticity ratios, K values, etc.), even though these metrics make different, contradictory assumptions about the distribution of latent memory signals, and even though all of their assumptions are frequently incorrect. We suggest that in order for the psychology and neuroscience of memory to become a more cumulative, theory-driven science, more attention must be given to measurement issues. We make a concrete suggestion: the default memory task for those simply interested in performance should change from old/new ("did you see this item'?") to two-alternative forced-choice ("which of these two items did you see?"). In situations where old/new variants are preferred (e.g., eyewitness identification; theoretical investigations of the nature of memory signals), receiver operating characteristic (ROC) analysis should be performed rather than a binary old/new task.
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