Apparent relative motion from a checkerboard surround

To better understand the Ouchi illusion in which a stationary picture generates illusory relative motion, the spatial properties of the constituent elements of the rectangular checkerboard background were examined. Results of experiment 1 revealed that the largest illusion was obtained with elements of approximately 20-30 min in width and 4-6 min in height, an orientation of the constituents that was orthogonal to that of the test grating, and a phase shift of the alternate stripes that was close to 180 degrees. In experiment 2 it was found that the illusion increased in magnitude with increasing achromatic contrast but was minimal with a pattern of high chromatic contrast near isoluminance. In experiment 3, two test patches were presented simultaneously in the checkerboard background and were varied independently in their orientation to explore whether or not their motions were perceived as coherent (common fate). Patches having identical orientations, and nearly orthogonal to the surround, were synchronized more strongly than those having reflected orientations. Hysteresis related to the gain control of spatially overlapping visual units differing in their polarity (ON/OFF) was discussed as a possible cause of this phenomenon.     

Timing ability and numerical competence in rats.

Counting and timing ability in Wistar rats was tested in 4 psychophysical choice experiments. After training naive rats with discrete sound sequences that confounded time and number, only time gained control of behavior; control by time was stronger and acquired more rapidly after training with separate time- and number-relevant signals. Two nonnumeric cues associated with periodic sequences, temporal ratio and sequence pattern, did not appear to provide the basis for numerical discrimination, as performance was unaffected by a sudden change from periodic signals to signals with unique temporal patterns. Even after highly accurate performance with number, time showed exclusive control of behavior for signals with conflicting time and number cues. This study provides an unequivocal demonstration that rats can count, but they do so according to H. Davis and J. Memmott's (1983) "last resort" hypothesis. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Weight perception and the haptic size–weight illusion are functions of the inertia tensor.

The complex effects of mass and volume on weight perception (e.g., the size-weight illusion) were hypothesized to follow simply from invariants of rotational dynamics. In Experiments 1-3, the rotational inertia of wielded, occluded objects was varied independently of mass, size, and torque. Perceived heaviness depended only on rotational inertia. Reanalysis of J. C. Stevens and L. L. Rubin's (1970) study revealed that size's influence on weight perception depends on specific patterns of the eigenvalues of the inertia tensor. These patterns were simulated in Experiments 4-6 with objects of fixed mass, volume, and visible size. Perceived heaviness decreased and increased, respectively, over object sets with the eigenvalue patterns of (a) constant mass, increasing volume and (b) increasing mass, constant volume. Weight perception and the size-weight illusion depend on stimulus invariants, not inference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synchronicity of frequently sampled, 24-h concentrations of circulating leptin, luteinizing hormone, and estradiol in healthy women

Leptin, an adipocyte hormone, is a trophic factor for the reproductive system; however, it is still unknown whether there is a dynamic relation between fluctuations in circulating leptin and hypothalamic-pituitary-ovarian (HPO) axis hormones. To test the hypothesis that fluctuations in plasma leptin concentrations are related to the levels of luteinizing hormone (LH) and estradiol, we sampled plasma from six healthy women every 7 min for 24 h during days 8-11 of the menstrual cycle. Cross-correlation analysis throughout the 24-h cycle revealed a relation between release patterns of leptin and LH, with a lag of 42-84 min but no significant cross-correlation between LH and estradiol. The ultradian fluctuations in leptin levels showed pattern synchrony with those of both LH and estradiol as determined by cross-approximate entropy (cross-ApEn). At night, as leptin levels rose to their peak, the pulsatility profiles of LH changed significantly and became synchronous with those of leptin. LH pulses were fewer, of longer duration, higher amplitude, and larger area than during the day. Moreover, the synchronicity of LH and leptin occurred late at night, at which time estradiol and leptin also exhibited significantly stronger pattern coupling than during the day. We propose that leptin may regulate the minute-to-minute oscillations in the levels of LH and estradiol, and that the nocturnal rise in leptin may determine the change in nocturnal LH profile in the mid-to-late follicular phase that precedes ovulation. This may explain the disruption of hypothalamic-pituitary-ovarian function that is characteristic of states of low leptin release, such as anorexia nervosa and cachexia.     

A novel speed illusion involving expansion and rotation patterns

Using random dot stimuli well controlled for dot speed, we found that the moving features in expanding patterns appear to move faster than those in rotating patterns. The illusion is well correlated with the strength of the global motion signal. For example, in displays where the number of motion directions defining the patterns is reduced, the magnitude of the illusion decreases. Similarly, the strength of the effect diminishes as dot density is reduced. In patterns where only wedge-shaped segments of the stimuli are left exposed, the difference in perceived speed increases with the angular size of the wedge. Stimulus placement relative to the fixation point has little effect on the persistence of this phenomenon-expansion patterns appear to contain elements of greater speed, independent of stimulus eccentricity. These results argue against a local explanation for this perceptual illusion, suggesting that the global motion pattern of the stimulus, per se, is responsible.     

Bilaterally projecting neurons in the two visual pathways of chicks

The influence of stereoscopic vision on the perception of optic flow fields was investigated in experiments based on a recently described illusion. In this illusion, subjects perceive a shift of the center of an expanding optic flow field when it is transparently superimposed by a unidirectional motion pattern. This illusory shift can be explained by the visual system taking the presented flow pattern as a certain self-motion flow field. Here we examined the dependence of the illusory transformation on differences in depth between the two superimposed motion patterns. Presenting them with different relative binocular disparities, we found a strong variation in the magnitude of the illusory shift. Especially when translation was in front of expansion, a highly significant decrease of the illusory shift occurred, down to 25% of its magnitude at zero disparity. These findings confirm the assumption that the motion pattern is interpreted as a self-motion flow field. In a further experiment we presented monocular depth cues by changing dot size and dot density. This caused a reduction of the illusory shift which is distinctly smaller than under stereoscopic presentation. We conclude that the illusory optic flow transformation is modified by depth information, especially by binocular disparity. The findings are linked to the phenomenon of induced motion and are related to neurophysiology.     

"Assimilation Theory and the Ponzo Illusion: Quantitative Predictions": Erratum.

Reports an error in "Assimilation theory and the Ponzo illusion: Quantitative predictions" by A. W. Pressey, N. Butchard and L. Scrivner (Canadian Journal of Psychology Revue Canadienne de Psychologie, 1971[Dec], Vol 25[6], 486-497). A corrected formula is provided. (The following abstract of the original article appeared in record 1972-10045-001.) Predicted that the ponzo illusion would increase, and then decrease as angle of the oblique arms increased, on the basis of assimilation theory. A reversed illusion was predicted when the angle was very obtuse. 4 orientations of the ponzo illusion were employed. In these the apex pointed to the top, bottom, left, and right. A different orientation was used on each of 4 sessions separated by a minimum of 1 day. The order was randomized for each of 9 men and 6 women ss. Both predictions were verified. Data suggest a change in the attentive field postulate of assimilation theory, and a general formula was derived to obtain a numerical estimate of illusion. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The motion analogue of the Café Wall illusion

Detecting visual motion is computationally equivalent to detecting spatiotemporally oriented contours. The question addressed in this study is whether the illusory oriented contour in the space-space domain induces corresponding illusory motion perception. Two experiments were conducted. In experiment 1, the Café Wall pattern, which elicits a strong illusion of orientation (Café Wall illusion), was found to induce an illusion of motion when this pattern was converted to the space-time domain. The strength of the motion illusion depends on the mortar luminance and width, as for the Café Wall illusion. In experiment 2, the adaptation to this illusion of motion was found to induce a motion aftereffect in a static test, which indicates that a first-order-motion system contributes to the induction of the motion illusion. In fact, the motion-energy model was able to predict the strength of this motion aftereffect.     

Carcinogenesis in tissue culture 26: malignant transformation of rat liver cells in vitro associated with paradoxical electrokinetic changes

Periodical examinations of the electrophoretic mobility of rat liver cells of two culture strains, RLC-10(2) and JTC-25.P3, were performed after the treatment with 3.3 X 10(-6) M 4-nitroquinoline 1-oxide (4NQO) for 30 min in culture. As early as 47th day after a single treatment with 4NQO, both control and treated cells of RLC-10(2) were found to produce tumors in animals on back-transplantation. At this stage, however, little difference was yet observed in electrokinetic patterns between the treated cells and the original antecedent cells. In contrast, a subline, JTC-25.P3, treated twice with 4NQO under the same conditions demonstrated a malignant electrokinetic pattern resembling that of rat ascites hepatocarcinoma strains, although its tumorigenicity was not verified. These discrepancies between changes of electrokinetic pattern and tumorigenicity were discussed with special references to the antigenic difference between cultured cell strains and each original host rats.     

Development of patterns of respiratory activity in unanesthetized fetal sheep in utero

Respiratory activity (diaphragmatic electromyogram) was recorded in six unanesthetized in utero fetal lambs, between 0.7 of gestation and term. Respiratory patterns generated by the fetus showed developmental changes that included 1) an emergence of a periodic modulation of respiratory rate producing alternating active and quite phases (mean cycle length of 37 min between 130 and 140 days' gestation; 2) an increase in percentage apnea (expiratory time greater than 10 s) from 20% at 110 days to 60% at 140 days; and 3) a linear decrease in the 2-h average respiratory rate, while mean rate during active phases showed no consistent gestational decline. Electrocortical and electroocular activity was monitored in three of six fetuses; however, discrete sleep state patterns could not be consistently identified. The results demonstrate a gestational change in the respiratory patterns of the developing fetus and suggest an orderly maturation of the mechanisms controlling respiratory neuronal output.     

"The tenacity of historical misinformation: Titchener did not invent the Titchener illusion": Correction.

Reports an error in the original article by G. Burton ( History of Psychology, 2001[Aug], Vol 4[3], pp. 228-244). In this article, the author asserted that a motivation textbook by R. C. Beck (see record 1979-32908-000) falsely listed a monkey as one of the objects in which L. Albert was tested for generalization of his supposed fear of fuzzy objects. In fact, Beck accurately indicated that the monkey was used during the pretest to determine Albert's preexisting fears; Beck did not claim that the monkey was used during the generalization phase. (The following abstract of this article originally appeared in record 2001-07674-002.) Some well-known psychological "facts" are actually false, but dispelling them is difficult. One such false fact is that Titchener introduced the illusion depicting a circle ringed by smaller circles, which appears larger than an equivalent circle surrounded by larger circles. A review of contemporary sources indicates that Ebbinghaus probably introduced this illusion in the 1890s, although not in any explicit publication, and Titchener neither had nor asserted any authorship of this figure. There are also 3 other illusions that are sometimes labeled the Ebbinghaus illusion... (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Assimilation theory and the Ponzo illusion: Quantitative predictions.

[Correction Notice: An erratum for this article was reported in Vol 26(2) of Canadian Journal of Psychology Revue Canadienne de Psychologie (see record 2007-04524-001). A corrected formula is provided.] Predicted that the ponzo illusion would increase, and then decrease as angle of the oblique arms increased, on the basis of assimilation theory. A reversed illusion was predicted when the angle was very obtuse. 4 orientations of the ponzo illusion were employed. In these the apex pointed to the top, bottom, left, and right. A different orientation was used on each of 4 sessions separated by a minimum of 1 day. The order was randomized for each of 9 men and 6 women ss. Both predictions were verified. Data suggest a change in the attentive field postulate of assimilation theory, and a general formula was derived to obtain a numerical estimate of illusion. (french summary) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of awakening cortisol and psychological distress in diurnal variations in affect: A day reconstruction study.

People often feel unhappy in the morning but better later in the day, and this pattern may be amplified in the distressed. Past work suggests that one function of cortisol is to energize people in the morning. In a study of 174 students, we tested to see whether daily affect patterns, psychological distress, and awakening cortisol levels were interlinked. Affect levels were assessed using the Day Reconstruction Method and psychological distress was measured using the Depression Anxiety Stress Scales. On average, positive affect increased markedly in a linear pattern across the day, whereas negative affect decreased linearly. For the highly distressed, this pattern was stronger for positive affect. Lower than average morning cortisol, as assessed by two saliva samples at waking and two samples 30 min after waking, predicted a clear increasing pattern of positive affect throughout the day. When we examined the interlinkages between affect patterns, distress, and cortisol, our results showed that a pronounced linear increase in positive affect from morning through to evening occurred chiefly among distressed people with below average cortisol levels upon awakening. Psychological distress, although not strongly associated with morning cortisol levels, does appear to interact with cortisol levels to profoundly influence affect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Spectral regularity as a factor distinct from harmonic relations in auditory grouping.

When the regular spectral pattern formed by an odd-harmonic complex (the base) is disrupted by an added even harmonic, the added component is judged as more salient than its neighbors. This study considered whether the effects of spectral pattern on perceptual segregation are restricted to harmonic stimuli. Participants either rated the clarity or judged the relative pitch of a cued component in a series of complex tones. The difference in clarity between added and base components found for the harmonic complexes was not reduced when the complexes were made inharmonic either by a frequency shift or by spectral stretch or compression. However, the added-base difference could be abolished for an inharmonic complex when the distribution of components across frequency was made uniform. These findings suggest that spectral regularity is a factor distinct from harmonic relations in auditory grouping. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The octave illusion revisited: Suppression or fusion between ears?

The octave illusion occurs when each ear receives a sequence of tones alternating by 1 octave but with the high and low tones in different ears. Most listeners perceive these stimuli as a high pitch in one ear alternating with a low pitch in the other ear. D. Deutsch and P. L. Roll (1976) interpreted this phenomenon as evidence for a what-where division of auditory processing caused by sequential interactions between the tones. They argued that the pitch follows the frequency presented to the dominant ear but is lateralized toward the higher frequency component. This model was examined in 4 experiments. Results indicate that the perceived pitch approximates the fundamental frequency and that the illusion does not depend on sequential interactions. The octave illusion may arise from an interaction between dichotic fusion and binaural diplacusis rather than from suppression as proposed by Deutsch. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Rhythm generation in organotypic medullary cultures of newborn rats

Organotypic transverse medullary slices (obex level) from six-day-old rats, cultured for two to four weeks in chemically defined medium contained rhythmically discharging neurones which were activated by CO2 and H+. The mechanisms underlying this rhythmicity and the spread of excitation and synaptic transmission within this organotypic tissue were examined by modifying the composition of the external solution. Our findings showed that (1) Exposure to tetrodotoxin (0.2 microM) or to high magnesium (6 mM) and low calcium (0.2 mM) concentrations abolished periodic activity. (2) Neither the blockade of GABAergic potentials with bicuculline methiodide (200 microM) and/or hydroxysaclofen (200 microM) nor the blockade of glycinergic potentials with strychnine hydrochloride (100 microM) abolished rhythmicity. (3) While atropine sulphate (5 microM) was ineffective in modulating periodic discharges nicotine (100 microM) - like CO2-shortened the intervals between the periodic events; hexamethonium (50-100 microM) reduced both periodic and aperiodic activity. (4) Exposure to the NMDA antagonist 2-aminophosphonovaleric acid (50 microM) suppressed periodic events only transiently. In the presence of 2-aminophosphonovaleric acid rhythmicity recovered. However, the AMPA-antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (10-50 microM), abolished periodic activity reversibly within less than 5 min. When 6-cyano-7-nitroquinoxaline-2,3-dione and nicotine were administered simultaneously periodic events persisted for up to 10 min. These findings indicate that synaptic excitatory drive is a prerequisite for the generation of rhythmic discharges of medullary neurones in this preparation. This drive may activate voltage-dependent channels or it may facilitate endogenous cellular mechanisms which initiate oscillations of intracellular calcium concentration. To test the latter possibility (5) calcium antagonists were added to the bath saline. The organic calcium antagonists verapamil and flunarizine (50-100 microM each) and the inorganic calcium antagonists cobalt (2 mM) and magnesium (6 mM) suppressed periodic activity and abolished or weakened the chemosensitivity towards CO2/acidosis. (6) Dantrolene (10 microM). an inhibitor of intracellular calcium release decreased the periodicity, while thapsigargin (2 microM) which blocks endoplasmic Ca(2+)-ATPase, transiently accelerated the occurrence of periodic events. (7) Oscillations of intracellular free calcium concentrations in Fura-2 AM-loaded cells were weakened or abolished by cobalt (2 mM). The results of (5)-(7) indicate that transmembrane calcium fluxes as well as intracellular Ca(2+)-release and -clearance mechanisms are a prerequisite for intracellular free calcium oscillations which may be important in the generation of rhythmic discharges in medullary neurones.     

Generalized peroxisomal disorder in male twins: fatty acid composition of serum lipids and response to n-3 fatty acids

Ischemia leads to intracellular acidification which can be counteracted by the Na+/H+-exchange mechanism. A blockade of this exchanger has been hypothesized to cause stronger intracellular acidification in the course of ischemia thereby protecting the heart from ischemic damage. The aim of our study was to find out (1) whether in the course of ischemia areas become electrically silent, (2) whether this is enhanced by the Na+/H+-exchange inhibitor cariporide (4-Isopropyl-3-methylsulfonylbenzoyl-guanidine; Hoe 642) and whether cariporide has protective effects. Therefore, we submitted isolated rabbit hearts, perfused according to the Langendorff technique to regional ischemia (LAD occlusion) for 30 min followed by 30 min reperfusion with (n=7) or without (n=7) pre-treatment with 1 microM cariporide. Under these conditions 256-channel epicardial potential mapping was carried out. Under non-ischemic conditions cariporide did not alter any of the parameters under observation. We found that ischemia led to marked alterations of the activation pattern, to action potential shortening and a marked increase in the dispersion of refractoriness. In the ischemic region there was a significant ST deviation from the isoelectrical line (control 32+/-10; 30 min ischemia: 290+/-35 arbitrary units [a.u.]). This was markedly reduced by cariporide (control 39+/-10; 30 min ischemia: 170+/-25 a.u.). The increase in dispersion by ischemia (by 50+/-5 ms) was significantly counteracted by cariporide (increased dispersion by 20+/-4 ms). In a similar way the alteration of the activation pattern was antagonized. Under the influence of cariporide we found a lower increase in the left ventricular enddiastolic pressure, and a significantly slower recovery of the action potential duration. After 30 min of ischemia 24+/-5 (control series) 24.5+/-5 mm2 (cariporide) became electrically silent. In a second series of experiments the incidence of arrhythmia was assessed: we found ventricular fibrillation in 6/7 untreated control hearts and in 4/7 cariporide treated hearts. In a third series of experiments we determined the intracellular [ATP] after 30 min of LAD occlusion using a histochemical method. We observed a decrease in [ATP] in the ischemic region as compared to the non-ischemic right ventricular wall, which was less pronounced in cariporide-treated hearts. Thus, we conclude that (1) cariporide protects the heart from ischemic damage and (2) at least under these conditions an enlargement of the electrically silent area did not occur.     

Comparing effects of the horizontal-vertical illusion on grip scaling and judgment: Relative versus absolute, not perception versus action.

The discovery that the prehension component of an open-loop, two-fingered reach is largely immune to certain salient pictorial illusions has been used to suggest that humans possess 2 distinct visual systems, 1 that subserves perceptual judgment and 1 that mediates visually controlled action. In this article, the authors present evidence that suggests that the critical distinction is not that of reaching and judgment but of relative and absolute perception. Experiment 1 extends the findings of S. Aglioti, J. F. X. DeSouza, and M. A. Goodale (1995) and suggests that the manual prehension component of open-loop reaching is affected by the horizontal-vertical illusion to a much smaller degree than perceptual size judgments. In Experiments 2 and 3, however, when perceptual size judgment is directed at a single element of the display, this difference vanishes. Experiment 4 demonstrates that grip scaling is strongly affected by the illusion when a single reach is scaled to both the horizontal and vertical components of a triangular figure. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Extracellular K+ induces locomotor-like patterns in the rat spinal cord in vitro: comparison with NMDA or 5-HT induced activity

Bath-application of increasing concentrations of extracellular K+ elicited alternating motor patterns recorded from pairs of various lumbar ventral roots of the neonatal rat (0-2 days old) spinal cord in vitro. The threshold concentration of K+ for this effect was 7.9 +/- 0.8 mM (mean +/- SD). The suprathreshold concentration range useful to evoke persistent motor patterns (lasting >/=10 min) was very narrow ( approximately 1 mM) as further increments elicited only rhythmic activity lasting from 20 s to a few minutes. On average, the fastest period of rhythmic patterns was 1.1 +/- 0.3 s. Intracellular recording from lumbar motoneurons showed that raised extracellular K+ elicited membrane potential oscillations with superimposed repetitive firing. In the presence of N-methyl--aspartate (NMDA) or non-NMDA receptor blockers [R(-)-2-amino-phosphonovaleric acid or 6-cyano-7-nitroquinoxaline-2,3-dione, respectively] extracellular K+ increases could still induce motor patterns although the threshold concentration was raised. Serotonin (5-HT) also induced alternating motor patterns (threshold 15 +/- 7 microM) that were consistently slower than those induced by high K+ or NMDA. Ritanserin (1 microM) prevented the locomotor-like activity of 5-HT but not that of high K+ provided the concentration of the latter was further increased. Subthreshold concentrations of K+ became effective in the presence of subthreshold doses of 5-HT or NMDA, indicating mutual facilitation between these substances. The fastest pattern frequency was observed by raising K+ or by adding NMDA. In the presence of 5-HT, the pattern frequency was never as fast even if NMDA (or high K+) was coapplied. Furthermore, application of 5-HT significantly slowed down the K+- or NMDA-induced rhythm, an effect strongly potentiated in the presence of ritanserin. It is suggested that the operation of the spinal locomotor network was activated by rises in extracellular K+, which presumably led to a broad increase in neuronal excitability. Whenever the efficiency of excitatory synaptic transmission was diminished (for example by glutamate receptor antagonism), a larger concentration of K+ was required to evoke locomotor-like patterns. The complex effect (comprising stimulation and inhibition) of 5-HT on alternating pattern generation appeared to result from a dual action of this substance on the spinal locomotor network.     

Periodicity of Carbon Element Distribution Along Casting Direction in Continuous-Casting Billet by Using Singular Spectrum Analysis

The periodicity of carbon element distributions along the casting direction in a continuous-casting billet was investigated quantitatively in this article after finding it in the preceding research. By using singular spectrum analysis (SSA), this study focuses on the changes of periodicity at different positions (centerline position, V-shaped segregation band, and columnar-to-equiaxed transformation position), at different data layouts (continuous or discrete) and at different scales (large scale or small scale). SSA is a frequency-domain mathematical method. Based on SSA, two values, the extracting average period value (P _ea) and the extracting comprehensive harmonic extent (E _ech), have been defined for investigating the periodic characteristics of time series, which reflects the influence of the segregation on the casting-direction quality stability (fluctuation frequency and disorder extent) of the billet. First, it is found that there are different periodic characteristics (period value and harmonic extent) at different positions as to the carbon element distribution along the casting direction in a continuous-casting billet, and the corresponding variation trend with position may be different at different data layouts or at different scales. Moreover, as to the studied element distributions, the variation trends of the period value with position in the same data layout results are the same, but it is different in the same scale results of different data layout; the variation trends of the harmonic extent with position in the same scale results are the same, but it is different in the same data layout results of a different scale. This point may reveal a universal phenomenon in the object of different data layouts and different scales. Hence, when the solidified element distribution, the related solidification process and the properties of steel product (especially about the fluctuation of quality) are investigated, special attentions should be paid to the data layout and the scale of the raw data.