The harmonic bandwidth of phase-reversal discrimination

Previous studies have shown that 180° relative phase shifts inf + 2f gratings are discriminated when the cosine or the sine component of the shift exceeds some-criterion (Bennett & Banks, 1987; Field & Nachmias, 1984). The current experiments demonstrate that this result holds-for other two-component gratings, provided that the components are within two to three octaves of each other. For frequency differences greater than two to three octaves, phase-reversal discrimination is impossible. A simple model that discriminates phase shifts on the basis of changes in the responses of even- and odd-symmetric spatial filters can account for the results.     

空间距离对视觉工作记忆巩固的影响

以往研究发现,个体对不同类型的视觉信息进行视觉工作记忆巩固的模式存在差异,如对于方向信息,一次只能有一个项目被巩固进入视觉工作记忆系统,而对于颜色信息,个体则可以一次巩固两个项目进入视觉工作记忆系统。但对于视觉信息的巩固模式是否会受其他因素的影响,目前仍然没有明确的定论。本研究将探讨视觉信息的巩固模式是否可能受到记忆项目空间距离因素的影响。研究采用变化觉察范式、序列-同时呈现操作及控制记忆项目呈现间距的方法,通过3个实验考察记忆项目之间的空间距离是否能够影响个体对颜色信息和方向信息的巩固模式。在三种空间距离水平上序列呈现或同时呈现两个记忆项目,实验结果一致发现记忆项目之间的空间距离会对视觉工作记忆巩固模式产生明显影响,个体在同时呈现条件下的正确率会随着空间距离的增大而降低。这些结果表明对同一类视觉信息进行巩固的过程中所存在的项目数量限制并不是固定的,个体可以采用序列模式或有限容量的并行模式对同一类信息进行巩固,巩固的模式可能与视觉空间注意的分配以及视觉信息所能获得的注意资源有关。     

The development of basic mechanisms of pattern vision: spatial frequency channels

The mature visual system possesses mechanisms that analyze visual inputs into bands of spatial frequency. This analysis appears to be important to several visual capabilities. We have investigated the development of these spatial-frequency channels in young infants. Experiment 1 used a masking paradigm to test 6-week-olds, 12-week-olds, and adults. The detectability of sine wave gratings of different spatial frequencies was measured in the presence and the absence of a narrowband noise masker. The 12-week data showed that at least two spatial-frequency channels with adultlike specificity are present at 12 weeks. The 6-week data did not reveal the presence of narrowband spatial-frequency channels. Experiment 2 used a different paradigm to investigate the same issue. The detectability of gratings composed of two sine wave components was measured in 6-week-olds and adults. The results were entirely consistent with those of experiment 1. The 12-week and adult data indicated the presence of narrowband spatial-frequency channels. The 6-week data did not. The results of these experiments suggest that the manner in which pattern information is processed changes fundamentally between 6 and 12 weeks of age.     

Anisotropic perception of visual angle: Implications for the horizontal-vertical illusion,overconstancy of size,and the moon illusion

Three experiments investigated anisotropic perception of visual angle outdoors. In Experiment 1, scales for vertical and horizontal visual angles ranging from 20° to 80° were constructed with the method of angle production (in which the subject reproduced a visual angle with a protractor) and the method of distance production (in which the subject produced a visual angle by adjusting viewing distance). In Experiment 2, scales for vertical and horizontal visual angles of 5°–30° were constructed with the method of angle production and were compared with scales for orientation in the frontal plane. In Experiment 3, vertical and horizontal visual angles of 3°-80° were judged with the method of verbal estimation. The main results of the experiments were as follows: (1) The obtained angles for visual angle are described by a quadratic equation, θ′=a+bθ+cθ² (where θ is the visual angle; θ′, the obtained angle;a, b, andc, constants). (2) The linear coefficientb is larger than unity and is steeper for vertical direction than for horizontal direction. (3) The quadratic coefficientc is generally smaller than zero and is negatively larger for vertical direction than for horizontal direction. And (4) the obtained angle for visual angle is larger than that for orientation. From these results, it was possible to predict the horizontal-vertical illusion, over-constancy of size, and the moon illusion.     

Monocular without stereopsis with and head movement

Random dots moving with various velocity gradients were presented to observers; the motion was yoked to head movement in one condition and to no head movement in another. In Experiment 1, 12 observers were shown motion gradients with sine, triangle, sawtooth, and square waveforms with amplitudes (equivalent disparities) of 12′ and 1° 53′. In Experiment 2, 48 observers were shown only the sinewave or square-wave gradient of 1° 53′ disparity either with or without head movement so that the observers’ expectation to see depth in one condition did not transfer to another. The main findings were: (1) with 12′ disparity, the head-movement condition produced perceived depth but almost no perceived motion, whereas the no-head-movement condition produced both perceived depth and perceived motion; (2) with 1° 53′ disparity, both conditions produced perceived depth and perceived motion; and (3) when the expectation to see depth was removed, the no-head-movement condition with the square-wave gradient produced no perceived depth, only motion. We suggest that monocular stereopsis with head movement can be achieved without perception of motion but monocular stereopsis without head movement requires perception of motion.     

Velocity perception for sounds moving in frequency space

In three experiments, we considered the relative contribution of frequency change (Δf) and time change (Δt) to perceived velocity (Δf/Δt) for sounds that moved either continuously in frequency space (Experiment 1) or in discrete steps (Experiments 2 and 3). In all the experiments, participants estimated “how quickly stimuli changed in pitch” on a scale ranging from 0 (not changing at all) to 100 (changing very quickly). Objective frequency velocity was specified in terms of semitones per second (ST/s), with ascending and descending stimuli presented on each trial at one of seven velocities (2, 4, 6, 8, 10, 12, and 14 ST/s). Separate contributions of frequency change (Δf) and time change (Δt) to perceived velocity were assessed by holding total Δt constant and varying Δf or vice versa. For tone glides that moved continuously in frequency space, both Δf and Δt cues contributed approximately equally to perceived velocity. For tone sequences, in contrast, perceived velocity was based almost entirely on Δt, with surprisingly little contribution from Δf. Experiment 3 considered separate judgments about Δf and Δt in order to rule out the possibility that the results of Experiment 2 were due to the inability to judge frequency change in tone sequences.     

Strength Recovery Patterns Following Isometric and Isotonic Exercise

In 3 experiments, the author tested the hypothesis that coordination dynamics is the content of a generalized motor program (GMP) for rhythmic interlimb coordination. In Experiment 1, learners (N = 14) practiced a ?90° movement with either identically timed or differently timed limbs. Both acquisition and transfer to novel (effector and pattern) timings were unaffected by the learning condition and were suggestive of the intrinsic dynamics for in-phase and antiphase. In Experiment 2, learners' (N = 13) acquisition of 2 different phase relations (?90° and ?45°) was qualitatively identical. Attractor reconstruction revealed an increase in the predictability of individual movement trajectories and a decrease in attractor dimensionality over learning. Transfer for both ?90° and ?45° was again suggestive of the intrinsic dynamics. In Experiment 3, learning altered participants' (N = 8) performance of in-phase and antiphase relations. Together, the results suggested a single continuum of phase relations, called an attractor landscape, that produces similar patterns of CE and VE for both previously stable and learned coordinations.     

A perceptual–attentional explanation of gaze following in 3‐ and 6‐month‐olds

Two experiments were conducted with 3‐ and 6‐month‐olds using a standard gaze following procedure with targets to examine the possibility that perceptual–attentional constraints may affect young infants’ gaze following. In Experiment 1, either moving or stationary targets were positioned at 15° from the infants’ midline. In Experiment 2, stationary targets were positioned at either 25° or 40° from the infants’ midline. Gaze following was evaluated with three criteria. Infants made significantly more correct responses to the 15° stationary targets than all other response types combined. When targets were moving or further away, infants made significantly more correct than incorrect responses when they made a turn; however, they did not make significantly more correct responses across all trials. It is argued that the infants’ responses are indicative of perceptual–attention constraints operating where the adult head and eye turn shifts infants’ attention to the side but whether the infants then ‘gaze follow’ depends on the structure of the environment as well as the infants’ ability to disengage attention and initiate saccadic eye movements.     

CONSTRUCTING AND DERIVING RECIPROCAL TRIGONOMETRIC RELATIONS: A FUNCTIONAL ANALYTIC APPROACH

Participants were pretrained and tested on mutually entailed trigonometric relations and combinatorially entailed relations as they pertained to positive and negative forms of sine, cosine, secant, and cosecant. Experiment 1 focused on training and testing transformations of these mathematical functions in terms of amplitude and frequency followed by tests of novel relations. Experiment 2 addressed training in accordance with frames of coordination (same as) and frames of opposition (reciprocal of) followed by more tests of novel relations. All assessments of derived and novel formula‐to‐graph relations, including reciprocal functions with diversified amplitude and frequency transformations, indicated that all 4 participants demonstrated substantial improvement in their ability to identify increasingly complex trigonometric formula‐to‐graph relations pertaining to same as and reciprocal of to establish mathematically complex repertoires.     

视觉表象操作加工的眼动实验研究

本研究通过视觉表象旋转和扫描的眼动实验探讨表象的心理表征方式。实验一结果表明,眼动指标具有与反应时相类似的旋转角度效应。实验二结果显示,表象扫描的反应时和眼动指标都具有与知觉扫描加工一样的距离效应。由此可以认为,表象眼动与知觉眼动模式具有相似性;表象具有相对独立的心理表征方式并有其特殊的加工过程;表象的心理表征可以是形象表征,而非一定是抽象的命题或符号表征     

Auditory feedback in music performance: Evidence for a dissociation of sequencing and timing

Four experiments examined temporal relationships between actions and auditory feedback in music performance. Experiment 1 incorporated phase shifts of feedback, which disrupted produced timing but not overall accuracy. Experiment 2 incorporated period shifts of pitch contents for synchronized feedback that primarily disrupted accuracy more than timing. Experiment 3 incorporated combined phase and period shifts, which caused moderate disruption to timing and accuracy and revealed interactive effects of period and phase shifts on production. A 4th experiment included all feedback conditions in the same session to confirm differences across Experiments 1-3. These results are consistent with the view that actions and their perceptual consequences are coordinated in a way that distinguishes timing (phase shifts) from sequencing (period shifts). ((c) 2003 APA, all rights reserved)     

The effect of white-noise mask level on sinewave contrast detection thresholds and the critical-band-masking model

It is known that visual noise added to sinusoidal gratings changes the typical U-shaped threshold curve which becomes flat in log-log scale for frequencies below 10c/deg when gratings are masked with white noise of high power spectral density level. These results have been explained using the critical-band-masking (CBM) model by supposing a visual filter-bank of constant relative bandwidth. However, some psychophysical and biological data support the idea of variable octave bandwidth. The CBM model has been used here to explain the progressive change of threshold curves with the noise mask level and to estimate the bandwidth of visual filters. Bayesian staircases were used in a 2IFC paradigm to measure contrast thresholds of horizontal sinusoidal gratings (0.25-8 c/deg) within a fixed Gaussian window and masked with one-dimensional, static, broadband white noise with each of five power density levels. Raw data showed that the contrast threshold curve progressively shifts upward and flattens out as the mask noise level increases. Theoretical thresholds from the CBM model were fitted simultaneously to the data at all five noise levels using visual filters with log-Gaussian gain functions. If we assume a fixed-channel detection model, the best fit was obtained when the octave bandwidth of visual filters decreases as a function of peak spatial frequency.     

Mapping the political language of the 1998 good friday agreement

The political statements of 12 prominent politicians involved in the 1998 Good Friday Agreement were examined using Diction (Hart, 1984a & 1995), a text analysis program that yields five measures of language variability: Optimism, Activity, Realism, Commonality, and Certainty. It was predicted that multi-dimensional scaling (MDS) would indicate that three of these variables could be used to group the politicians on the basis of their published policy positions. MDS indicated that the language of the politicians could be plotted on two dimensions. Activity, with an angle of 31.8°, and Optimism, with an angle of 35.9°, represent the first dimension. Realism loaded significantly on Dimension 2 which has an angle of 42.2°. Limitations of text analysis programs are considered together with suggestions for future developments.     

The role of eye height in perceiving affordances and object dimensions

In four experiments on perceived object height and width, the effects of shifting participants’ effective eye height (EEH) on affordance (intrinsic) and apparent size (extrinsic) judgments were con-trasted. In Experiment 1, EEH shifts produced comparable overestimations ofheight in intrinsic and extrinsic tasks. A similar result was found with a more abstract extrinsic height task (Experiment 2). However, Experiment 3 revealed a dissociation between intrinsic and extrinsic tasks of perceivedwidth. Affordance judgments were affected by EEH shifts, whereas apparent size judgments were not. Experiment 4 compared participants’ performance on comparable extrinsic tasks of height and width. Height judgments were affected by EEH shifts, but width judgments were again unaffected. It is concluded that eye height may be a more natural metric for object height than for width. Moreover, this difference reflects a basic flexibility within the human visual system for selectively attuning to the most accessible sources of size information.     

Spatial memory in rats under restricted viewing conditions

In a procedure devised by J. A. Walker and D. S. Olton (Learning and Motivation, 1979, 10, 73–84), rats were placed on two arms of a four-arm radial maze and then were placed in the center of the maze to test how accurately they could choose the alleys on which they had not been placed. In three experiments, the conditions under which animals viewed the environment from the arms were varied. In Experiment 1, both the extent of spatial view and the exposure time were varied factorially in a within-subjects design; animals viewed the environment down a tunnel or had a 180° or 360° view, and subjects were allowed to view the environment for either 2 or 20 sec. In Experiment 2, a between-subjects design was used, in which different groups of subjects were tested repeatedly under either the tunnel, 180°, or 360° conditions. Both experiments showed that animals could avoid the arms previously visited at no better than a chance level of accuracy in the tunnel viewing condition but could perform with progressively better accuracy at the 180 and 360° viewing conditions. Animals also were more accurate in Experiment 1 after viewing for 20 sec than after viewing for 2 sec. Experiment 3 involved a procedure in which restricted viewing conditions were used both during arm placements and testing. Animals tested under tunnel viewing eventually achieved above-chance performance with this procedure, but did not exceed chance as rapidly as groups tested with 45 and 90° views of the environment. These results suggest that animals can learn about their position in a spatial environment through observation and that an animal's ability to locate its position is directly related to the extent of the surrounding environment it can see and the length of time it is allowed to look. The implications of these findings for list and map hypotheses of spatial memory representation are discussed.     

Observational drawing biases are predicted by biases in perception: Empirical support of the misperception hypothesis of drawing accuracy with respect to two angle illusions

We tested the misperception hypothesis of drawing errors, which states that drawing accuracy is strongly influenced by the perceptual encoding of a to-be-drawn stimulus. We used a highly controlled experimental paradigm in which nonartist participants made perceptual judgements and drawings of angles under identical stimulus exposure conditions. Experiment 1 examined the isosceles/scalene triangle angle illusion; congruent patterns of bias in the perception and drawing tasks were found for 40 and 60° angles, but not for 20 or 80° angles, providing mixed support for the misperception hypothesis. Experiment 2 examined shape constancy effects with respect to reproductions of single acute or obtuse angles; congruent patterns of bias in the perception and drawing tasks were found across a range of angles from 29 to 151°, providing strong support for the misperception hypothesis. In both experiments, perceptual and drawing biases were positively correlated. These results are largely consistent with the misperception hypothesis, suggesting that inaccurate perceptual encoding of angles is an important reason that nonartists err in drawing angles from observation.     

Successive and conditional discrimination learning in pigs

We studied the ability of pigs to discriminate tone cues using successive and conditional discrimination tasks. Pigs (n = 8) were trained in a successive discrimination Go/No-Go task (Experiment 1) to associate a Go-cue with a reward at the end of a runway and a No-Go-cue with the absence of reward. Latency to reach the goal-box was recorded for each cue-type. Learning of a conditional discrimination task was compared between low-birthweight (LBW, n = 5) and normal-birthweight (NBW, n = 6) pigs (Experiment 2) and between conventional farm (n = 7) and Göttingen miniature (n = 8) pigs (Experiment 3). In this active-choice task, one cue signalled a response in a right goal-box was correct and a second cue signalled a response in a left goal-box was correct. Cues were differentially rewarded. The number of sessions to learn the discrimination and number of correct choices per cue-type were recorded. In Experiment 1, four out of eight pigs showed learning on the task, that is, a higher latency to respond to the No-Go-cue, within 25 sessions. In Experiment 2, eight out of 11 pigs learned the discrimination within 46 sessions. LBW learners learned faster than NBW learners. In Experiment 3, all 15 pigs learned the task within 16 sessions. Göttingen miniature pigs learned faster than conventional farm pigs. While some methodological issues may improve the Go/No-Go design, it is suggested that an active-choice task yields clearer and more consistent results than one relying on latency alone.     

Spatial frequency comparisons of rotated gratings

Reaction time for determining if two square-wave gratings are the same or different is a bimodal function of the relative angular separation (RAS) between them. Response time peaks at 60° and 120° separation and drops siguificantly at approximately 90°, provided that the gratings being compared are of the same spatial frequency. This pattern of results is not in line with those previously reported for more complex figures, nor may it be attributed to any “oblique effect,” since the same function is obtained with the comparison gratings placed at different retinal orientations. One possible explanation is that orthogonally tuned orientation channels interact in a facilitatory fashion in the human visual system.     

Co-speech iconic gestures and visuo-spatial working memory

Three experiments tested the role of verbal versus visuo-spatial working memory in the comprehension of co-speech iconic gestures. In Experiment 1, participants viewed congruent discourse primes in which the speaker's gestures matched the information conveyed by his speech, and incongruent ones in which the semantic content of the speaker's gestures diverged from that in his speech. Discourse primes were followed by picture probes that participants judged as being either related or unrelated to the preceding clip. Performance on this picture probe classification task was faster and more accurate after congruent than incongruent discourse primes. The effect of discourse congruency on response times was linearly related to measures of visuo-spatial, but not verbal, working memory capacity, as participants with greater visuo-spatial WM capacity benefited more from congruent gestures. In Experiments 2 and 3, participants performed the same picture probe classification task under conditions of high and low loads on concurrent visuo-spatial (Experiment 2) and verbal (Experiment 3) memory tasks. Effects of discourse congruency and verbal WM load were additive, while effects of discourse congruency and visuo-spatial WM load were interactive. Results suggest that congruent co-speech gestures facilitate multi-modal language comprehension, and indicate an important role for visuo-spatial WM in these speech–gesture integration processes.     

Deprivation and reward stimuli as compound stimuli

In Experiment 1 the experimental group was tested with a deprivation level and a reward magnitude which it had experienced previously but which it had not experienced in combination. This group was inferior in test performance to a group which had experienced the test deprivation-reward combination prior to test. These results were interpreted as indicating that deprivation stimuli and reward stimuli form a compound stimulus and training on the elements of the compound produces performance inferior to training directly on the compound. In Experiment 2, the decrement associated with two different shifts in deprivation and reward did not differ despite the different size change of total incentive involved in the two shifts. The results were interpreted as indicating that the deprivation-reward stimulus is not produced by a single underlying incentive mechanism.