Primates possess the remarkable ability to differentiate faces of group members and to extract relevant information about the individual directly from the face. Recognition of conspecific faces is achieved by means of holistic processing, i.e. the processing of the face as an unparsed, perceptual whole, rather than as the collection of independent features (part-based processing). The most striking example of holistic processing is the Thatcher illusion. Local changes in facial features are hardly noticeable when the whole face is inverted (rotated 180°), but strikingly grotesque when the face is upright. This effect can be explained by a lack of processing capabilities for locally rotated facial features when the face is turned upside down. Recently, a Thatcher illusion was described in the macaque monkey analogous to that known from human investigations. Using a habituation paradigm combined with eye tracking, we address the critical follow-up questions raised in the aforementioned study to show the Thatcher illusion as a function of the observer''s species (humans and macaques), the stimulus'' species (humans and macaques) and the level of perceptual expertise (novice, expert). 相似文献
1. 1.The sensations evoked by pairs of distinct thermal stimuli applied to the back of the hand were studied in 17 volunteer subjects. Four stimulus combinations were used; neutral-cold (NC), neutral-neutral (NN), neutral-warm (NW), and cold-warm (CW).
2. 2.The subjects were first asked to estimate the magnitude of the thermal sensations evoked by the thermal stimuli. On average, the four pairs were reported as increasing magnitude in the following order: NC, CW, NN, and NW, seeming to suggest that the subjects experienced the cold-warm combination as a composite sensation of cold and warmth intermediate between pure cold and pure warmth.
3. 3.When asked only to detect the presence of a cold stimulus, the subjects performed as well for the CW combination as for the CN combination. This second result indicates that the reported composite magnitude of CW does not result from a true opponency of cold and warmth but from a cognitive combination of distinct sensations of cold and warmth.
Author Keywords: Thermal sense; psychophysics; perception; sensory opponency; man 相似文献
High mountain grasslands offer multiple goods and services to society but are severely threatened by improper land use practices such as abandonment or rapid intensification. In order to reduce abandonment and strengthen the common extensive agricultural practice a sustainable land use management of high mountain grasslands is needed. A spatially detailed yield assessment helps to identify possible meadows or, on the contrary, areas with a low carrying capacity in a region, making it easier to manage these sites. Such assessments are rarely available for remote and inaccessible areas. Remotely sensed vegetation indices are able to provide valuable information on grassland properties. These indices tend, however, to saturate for high biomass. This affects their applicability to assessments of high-yield grasslands.The main aim of this study was to model a spatially explicit grassland yield map and to test whether saturation issues can be tackled by consideration of plant species composition in the modelling process. The high mountain grassland of the subalpine belt (1800 – 2500 m a.s.l.) in the Kazbegi region, Greater Caucasus, Georgia, was chosen as test site for its strong species composition and yield gradients.We first modelled the species composition of the grassland described as metrically scaled gradients in the form of ordination axes by random forest regression. We then derived vegetation indices from Rapid Eye imagery, and topographic variables from a digital elevation model, which we used together with the multispectral bands as predictive variables. For comparison, we performed two yield models, one excluding the species composition maps and one including the species composition map as predictors. Moreover, we performed a third individual model, with species composition as predictors and a split dataset, to produce the final yield map.Three main grassland types were found in the vegetation analysis: Hordeum violaceum-meadows, Gentianella caucasea-grassland and Astragalus captiosus-grassland. The three random forest regression models for the ordination axes explained 64%, 33% and 46% of the variance in species composition. Independent validation of modelled ordination scores against a validation data set resulted in an R2 of 0.64, 0.32 and 0.46 for the first, second and third axes, respectively. The model based on species composition resulted in a R2 = 0.55, whereas the benchmark model showed weaker relationships between yield and the multispectral reflectance, vegetation indices, and topographical parameters (R2 = 0.42). The final random forest yield model used to derive the yield map resulted in 62% variance explained and an R2 = 0.64 between predicted and observed biomass. The results further indicate that high yields are generally difficult to predict with both models.The benefit of including a species composition map as a predictor variable for grassland yield lies in the preservation of ecologically meaningful features, especially the occurrence of high yielding vegetation type of Hordeum violaceum meadows is depicted accurately in the map. Even though we used a gradient based design, sharp boundaries or immediate changes in productivity were visible, especially in small structures such as arable fields or roads (Fig. 6b), making it a valuable tool for sustainable land use management. The saturation effect however, was mitigated by using species composition as predictor variables but is still present at high yields. 相似文献
The protonmotive force in several sulfate-reducing bacteria has been determined by means of radiolabelled membrane-permeant probes (tetraphenyl-phosphonium cation, TPP+, for , and benzoate for pH). In six of ten freshwater strains tested only the pH gradient could be determine, while the membrane potential was not accessible due to nonspecific binding of TPP+. The protonmotive force of the other four strains was between –110 and –155 mV, composed of a membrane potential of –80 to –140 mV and a pH gradient between 0.25 and 0.8 (inside alkaline) at pHout=7. In Desulfobulbus propionicus the pH gradient decreased with rising external pH values. This decrease, however, was compensated by an increasing membrane potential. Sulfate, which can be highly accumulated by the cells, did not affect the protonmotive force, if added in concentrations of up to 4 mM. The highest sulfate accumulation observed (2500-fold), which occurred at external sulfate concentrations below 5 M, could be explained by a symport of three protons per sulfate, if equilibrium with the protonmotive force was assumed. At higher sulfate concentrations the accumulation decreased and suggested an electroneutral symport of two protons per sulfate. At sulfate concentrations above 500 M, the cells stopped sulfate uptake before reaching an equilibrium with the protonmotive force.Abbreviations CCCP
carbonyl cyanide m-chlorophenylhydrazone
- MOPS
morpholinopropanesulfonic acid
- TPP+
tetraphenylphosphonium cation
- EDTA
ethylenediaminetetraacetic acid
- pH
transmembrane pH gradient (pHin-pHout)
-
transmembrane electrical potential difference 相似文献
Summary Tongue-projecting plethodontid salamanders have massive direct ipsilateral retinal afferents to the tectum opticum as well as a large and well developed nucleus isthmi. Retrograde staining revealed two subnuclei: A ventral one projecting to the contralateral tectal hemisphere and a dorsal one projecting back to the ipsilateral side. The isthmic nuclei show a retinotopic organization, which is in register with that of the tectum. Electrophysiological recordings from nucleus-isthmi neurons revealed response properties that are very similar to those found in tectal neurons. Thus, there is no substantial processing of tectal neural activity in the nucleus isthmi. Measurements of peak latencies after electrical and light stimulation suggest the continuous coexistence of 4 representations of the visual field in the tectum mediated by (1) the contralateral and (2) the ipsilateral direct retinal afferents, (3) the uncrossed and (4) the crossed isthmo-tectal projection. (1) and (2) originate at the same moment in the retina and arrive simultaneously in the tectum. It is assumed that in plethodontid salamanders with massive ipsilateral retino-tectal projections depth perception based on disparity cues is achieved by comparison of these images.Representations mediated by (3) and (4) arriving in the tectum at the same time as (1) and (2) originate 10–30 ms earlier in the retina. It is hypothesized that these time differences between (1)/(2) and (3)/(4) are used to calculate three-dimensional trajectories of fast-moving prey objects.Abbreviations
EL
edge length
-
FDA
fluoresceine dextranamine
-
RDA
tetramethylrhodamine dextranamine
-
RF
receptive field 相似文献
All living trees (30 cm gbh) were enumerated in 104 80×80 m plots arranged along four transects in the Douala-Edea Forest Reserve Cameroun, a system of low-lying ancient coastal sand dunes interspersed by numerous streams and swamps. The extent of permanent and seasonal swamps was recorded for each plot. Two hundred thirty taxa were recognized of which 63% were identified to species. Mean tree density was 376 ha–1, basal area 31.0 m2 ha–1 and number of species per plot 39. The Olacaceae were the most abundant family in terms of basal area, but the Euphorbiaceae the most frequently represented. The most abundant species wasCoula edulis (Olacaceae). Twenty-two plots had most of their area permanently or seasonally swamped. Percentage sand, silt and clay ranged between 32–100, 0–64, 0–21% respectively. The ranges for other variables recorded were: pH (2.7–5.4), organic carbon (1.5–12.4%), available phosphorus (7–90 ppm) and potassium (28–188 ppm), and nitrogen (ammonium 4–40 ppm, nitrate 1–12 ppm).Classification of the plots on the basis of six soil variables provided three large distinct groups: swamp plots and non-swamp plots, the latter divided into plots of low and high available soil phosphorus. Swamp plots were distinguished by high abundances ofProtomegabaria stapfiana andLibrevillea klainei, though correspondence ordination of plots in these groups showedP. stapfiana associated with more clayey soils andLibrevillea klainei (andGluema ivorensis) on the very sandy soils. Direct gradient analysis highlighted several species associated with these lower phosphorus soils. Available soil phosphorus is not as low at Douala-Edea as in parts of Korup, and the association of these Douala-Edea soils with the Caesalpinioideae is correspondingly weaker.Nomenclature follows Aubréville (1963–1983).The field work was supported by grant numbers RR00167-14, RR00167-15 and RR0167-16 from the National Institutes of Health for the operation of the Wisconsin Regional Primate Research Center, and N.A.T.O. Scientific Affairs grant number 1748 (to PGW and JSG). It was greatly facilitated by the skill and dedication of Ferdinand Namata. R. M. Polhill and D. W. Thomas assisted considerably in the identification of plant species. Sue Gartlan collected and collated the meteorological data, besides other field support. In the field phase J.S.G., P.G.W. and D.B.McK. were researches attached to the National Office of Scientific and Technical Research (ONAREST), Yaoundé. We thank M. D. Swaine for comments on earlier drafts, R. Letouzey for checking species nomenclature, the Computer Unit at Stirling University for facilities, M. Burnett for the typing at Stirling, and the Department of Soil Science, University of Wisconsin, for undertaking the soil chemical analyses.Reprint requests to D.McC.N. at Stirling.Publication No. 23-025 of the Wisconsin Regional Primate Center. 相似文献
Research on visual blight has been predominantly qualitative and has pointed out salient attributes of blight: that it is durable, visually demeaning, and somehow aesthetically depressing. Data from a national sample (n=3005) are used in this study to measure the effect of demographic variation on the perception of visual blight. The perception of blight shows marked and regular variation with socioeconomic status, marital status, and religiosity.Harris data for this study was purchased with funds from the Shell Foundation. The author wishes to acknowledge Robert Q. Hanham, whose assistance proved invaluable. 相似文献
A method is proposed to analyse the dispersion profiles of species in classes of environmental variables, based on the decomposition of the expected frequencies in contingency tables with many interacting species. The method has been applied to data of dominant or very frequent graminoid species in grasslands of the Natisone Valley (Friuli, Italy). It allowed to make predictions by removing the random component of variation.Nomenclature follows: P. Zangheri (1976). Flora Italica, CEDAM, Padua.The authors were recipients of an Italian CNR grant (E. Feoli) and a Canadian NSERC grant (L. Orlóci) during tenure of this project. The results are in partial fulfillment of a commitment to the Centro Regionale per la Sperimentazione Agraria per il Friuli-Venezia Giulia. 相似文献