Sensory scaling and the psychophysical law

Sensory scaling is analysed as a sensori-motor task for which two relations must be determined, the first, S = f(I), being the relation between I, the stimulus intensity, and S, a measure of the neural effect of the stimulus, and the second being the relation between the subject's response, R, and S. It is shown that for any scaling procedure the relation between R and S can be arbitrarily specified, and according to the choice made S = f(I) will be found to be either a power function or a logarithmic function; these two “psycho- physical laws” do not reflect empirical differences between scaling procedures but conventional differences in the assumptions made when interpreting these procedures. A model is then elaborated in which S = f(I) is fixed and the relation between R and S depends on the demands of the psychophysical task and the effects of previous learning. With this more complex model the empirical implications of the power function and log function differ; it is shown that if the latter is accepted explanations can be given for two major problems in scaling theory, the disparity between the functions given by category scaling and the direct methods, and the difference between prothetic and metathetic continua.     

Imagery and compatibility of pairing in the free recall of adjective-noun pairs

Can the image-evoking value (I) of single words be used to predict the recall of grammatical units in which they occur? Thirty-two subjects free-recalled a list of 24 adjective-noun pairs varying in the I of the adjective and the noun, and the compatibility (C) of the pairing (i.e. whether or not the pair was immediately meaningful). Analysis showed all three variables to affect recall. High I adjectives facilitated recall irrespective of the I of the noun or the C of the pairing. Noun I and C facilitated recall only when both noun I was high and the pairing was compatible. An examination of intertrial repetitions failed to find evidence of organization in recall. Where only one word from a pair was recalled it tended to come from an incompatible pair, supporting the hypothesis that the recall of one word from an incompatible pair is less likely to cue recall of the other word than is the recall of one word from a compatible pair.     

Context effects in judging taste intensity: A comparison of variable line and category rating methods

The effect of stimulus range and stimulus spacing was examinedwhen subjects registered the perceived intensity of sweet liquids using either a matching procedure (Experiment 1) or category rating (Experiment 2). The matching procedure is conceptually similar to absolute magnitude estimation, whereby subjects match their impression of number size to their impression of the subjective magnitude of a stimulus. In Experiment 1, subjects matched their impression of the stimulus to their impression of the magnitude of the length of a continuously variable line under their control. In Experiment 2, subjects rated perceived sweetness on a vertical 13-point scale with five equally spaced verbal labels. In both experiments, three sets of four sucrose concentrations were employed. In two of these sets, a set of weaker solutions and a set of stronger solutions, concentrations were separated by 0.25 log units. In a third set, which spanned the range of concentrations used in the other two sets (0.87 to 27.36% w/v), solutions were separated by 0.5 log units. An examination ofboth individual and group data showed the matching procedure to be less susceptible to a range bias than the rating procedure. In particular, a single intensity function accommodated data from individual ranges better when the matching procedure was used than when the rating procedure was used. No effect of stimulus spacing was evident in the data from either procedure.     

知觉组织对时序知觉的双重影响:同时判断任务的证据

本研究探讨知觉组织对时序知觉的双重影响。实验采用三条线段构成的C形为实验材料,操纵图形朝向和SOA水平(实验1和实验2)、图形颜色(实验3)以及反应限制(实验4),要求被试完成同时判断任务。结果发现,在不同的SOA条件下,图形对向条件的同时判断频率均显著高于图形反向条件(实验1),即使在知觉组织线索弱化时这种现象仍然存在(实验2和实验3),而且知觉组织对时序知觉的影响不是由于被试的反应偏向导致的(实验4)。结果说明知觉组织对时序知觉存在双重影响:当两个刺激同时出现时,知觉组织能够提高时序知觉表现; 而当两个刺激非同时出现时,知觉组织显著降低时序知觉表现。     

Simultaneity constancy

Sound and light take different amounts of time to reach their respective receptors, to be transduced, and to be transmitted to the cortex. Their processing times also vary with factors such as intensity and retinal eccentricity. We assessed the capability of subjects to perceive simultaneity correctly despite these variations. Temporal asynchronies of up to 200 ms were introduced between the components of sound/light pairs. Using the method of constant stimuli, seven subjects judged which came first. Distance, and hence the times of arrival of paired visual and auditory targets, was varied from 1 to 32 m. Visual intensity was varied by viewing the target through 1.8 dB attenuating glasses, and a retinal eccentricity of 20 degrees was compared to central presentation. Despite large differences in reaction times, which varied in a predictable way with the stimulus parameters, the timing of sound/light pairings judged as simultaneous corresponded to when the light and sound left the source simultaneously. Almost complete compensation was found in all conditions tested, showing that these substantial but predictable variations in timing can be taken into account in creating simultaneity constancy.     

Lightness,brightness, and brightness contrast: 2. Reflectance variation

Changes of annulus luminance in traditional disk-and-annulus patterns can be perceived to be either reflectance or illuminance changes. In the present experiments, we examined the effect of varying annulus reflectance. In Experiment 1, we placed test and standard patch-and-surround patterns in identical Mondrian patchworks. Only the luminance of the test surround changed from trial to triaL., appearing as reflectance variation under constant illumination. Lightness matches were identical to brightness matches, as expected. In Experiment 2, we used only the patch and surround (no Mondrian). Instructions said that the illumination would change from trial to trial. Lightness and brightness-contrast data were identical; illumination gradients were indistinguishable from reflectance gradients. In Experiment 3, the patterns were the same, but the instructions said that the shade of gray of the test surround would change from trial to trial. Lightness matches were identical to brightness matches, again confirming the ambiguity of disk-and-annulus patterns.     

The response criterion,the stimulus configuration,and the relationship between brightness contrast and brightness constancy

Four experiments were designed to investigate the nature of the relationship between brightness contrast and brightness constancy while controlling the response criterion, the area of the surround, the stimulus configuration, and the mode of appearance of the modulus target. Ten Os in each of the four experiments estimated the apparent whiteness or brightness of targets with different contrast ratios. All targets were viewed at several illumination levels. Most constancy (whiteness and brightness) functions displayed shallow slopes that reflected a good approximation to constancy. The functions within Experiments I, III, and IV were vertically displaced and parallel; those in Experiment II were vertically displaced and increased in slope. This suggests that decreasing the contrast ratio had no effect on the tendency towards constancy when the area of the surround was greater than that of the target but resulted in a decrease in constancy when the area of the surround was equal to that of the target.     

Hue shift of induced colour as a function of luminance relations

The hue of induced colour was studied as a function of surround/test field luminance ratio using a chromatic surround and an achromatic central test field. The hue of the test field was determined by means of colour naming methods. Three inducing colours were used: blue (Wr No. 47), green (Wr No. 58), and red (Wr No. 25). The number of subjects was 9–11 in the two experiments. The luminance ratio (ranging from 0.07 to 17.1) was varied by varying the luminance of the test field (Experiment 1) or of the surround (Experiment 2). For the blue surround the results show a hue shift in accordance with the Bezold-Brücke phenomenon. For the inducing colours green and red the induced colours are weak, and the hue shifts are more or less unsystematic though there are individual subjects showing a trend in the Bezold-Brücke direction. It is concluded that the hue shifts depend on the luminance relations rather than on the test field luminance.     

Preferential processing of target features in texture segmentation

In five experiments, observers were required to detect a texture target and/or identify the orientation of elements composing target and nontarget regions. They were significantly worse at discerning the orientation of nontarget regions than at detecting target presence (Experiment 1). On the other hand, accuracy of identifying target orientation was found to be near 100% (Experiment 2). When observers were required only to identify surround orientation (Experiment 3), accuracy was diminished on target-present trials relative to that on target-absent trials. The superiority of target processing and the interference produced by target presence on surround processing were demonstrated in unpracticed observers (Experiment 4). In Experiment 5, it was found that information regarding target presence is available before information regarding feature values of the target. These findings are consistent with a model of visual attention and search that incorporates a fast generalized difference operator and a slower feature comparison process.     

On the relation between identifying and locating masked targets in visual search

Three experiments were designed to determine whether naming is contingent on locating in a visual search task. Subjects were required to identify a masked target whose location was known (I|L) or unknown (I) and to locate a masked target whose identity was known (L|I) or unknown (L). The location-contingent hypothesis predicts a relationship among the tasks such that P(L) P(I|L) = P(I), since P(I) and P(L) P(I|L) both estimate the joint probability of identifying and locating the target (i.e. P(IλL)). This relationship held in Experiment I where targets were presented alone, and in Experiment II where targets were presented with dots as noise elements, but not in Experiment III where Xs were noise elements. The results are discussed in terms of the generality of the location-contingent hypothesis.     

The effects of context change on long-term habituation of the orienting response in humans

Four experiments examined the effects of context change (Experiments 1-3) and context extinction (Experiment 4) on long-term habituation of the skin conductance response. In all experiments, subjects received 15 presentations of a target stimulus in each of two sessions. In Experiment 1 (N=60) there was a 15-min interval between training and test sessions. This interval was extended to 24 hours in Experiments 2 (N=60) and 3 (N=60). The experimental treatment in each of these studies involved a change in context between the two training sessions. None of the experiments provided evidence of context dependency in measures of long-term habituation. In Experiment 4 (N=60) experimental subjects received a period of context extinction during which they remained in the laboratory environment between two series of habituation trials. Again, however, there was no evidence that long-term habituation was contextually mediated. Thus, the results fail uniformly to support theories that argue that long-term habituation is context-dependent.     

Colour constancy in goldfish and man: influence of surround size and lightness

Colour constancy was investigated by using a series of 10 simultaneously presented surface colours ranging in small steps from green through gray to red-purple. Goldfish were trained to select one medium test field when the entire setup was illuminated with white light. In the tests, either red or green illumination was used. Colour constancy, as inferred from the choice behaviour, was perfect under green illumination when the test fields were presented on a gray or a white background, but imperfect on a black background. Under red illumination and a white background, however, colour constancy was overcompensated. Here, a colour contrast effect was observed. The influence of background lightness was also found when the surround was restricted to a narrow annulus of 4-11 mm width (test field diameter: 14 mm). By applying colour metrics it could be shown that the von Kries coefficient law can describe the overall effect of colour constancy. For an explanation of the effect of surround size and lightness, lateral inhibitory interactions have to be assumed in addition, which are also responsible for simultaneous colour contrast. Very similar results were obtained in experiments with the same colours in human subjects. They had to name the test field appearing 'neutral' under the different illumination and surround conditions, as tested in the goldfish experiment.     

Stimulus intensity and foreperiod effects in intersensory facilitation

Intersensory facilitation refers to the more rapid reaction time (RT) to a target in one modality and an accessory stimulus in a different modality compared to a RT to the target alone. Prior studies suggest two processes contribute to the phenomenon, termed the preparatory state and energy integration which refer to the action of accessory stimulation in providing forewarning and intensifying the reaction signal, respectively. Experiment I factorially varied foreperiod duration, light (target) intensity and tone (accessory) intensity in a discriminative RT task. The results were that foreperiod (preparatory state) and intensity (energy integration) effects were additive, implying that they affected separate processing stages. Accessory stimulus intensity affected false alarm rate on catch trials. This suggests that energy integration involves a form of response bias (increased likelihood of responding) and not facilitation (more rapid information processing). Experiment II indicated that comparable energy integration effects obtain with tone as target and light as accessory, as well as vice versa. The findings further indicated that RT to a bisensory pairing is more rapid when attention is directed to the more potent member of the pair.     

Individual differences in word recognition latency

Previous studies of the effects of word characteristics on word recognition have used orthogonal combinations of word variables and have failed to consider individual differences. The present study examined word naming (Experiment 1) and lexical decision (Experiment 2) tasks using an unrestricted set of words and a correlational analysis. Individual differences were considered using a measure of the subjects’ knowledge of the English vocabulary. The results of Experiment 1 indicated that log (RT) for word naming is affected by word length, word frequency, and the number of syllables in the word; the results of Experiment 2 confirmed the effects of length and frequency but also showed that log (RT) is a function of the age at which the word is introduced to a child’s reading vocabulary. Subjects with a high vocabulary score were more rapid in Experiment 1 but were slower in Experiment 2, compared to subjects with a low vocabulary score. More importantly, high-vocabulary subjects, in both studies, were less affected by word length than the low-vocabulary subjects. The results suggest that subjects do differ in their reading strategy and that word length and word frequency may affect different stages in the word recognition process.     

Redundancy effects in short-term memory

Five experiments are reported whose purpose was to demonstrate that short-term memory is improved by redundancy within the material. In Experiment I “tune” containing two, three, four and five tones of differing frequencies had to be coded into digits 1-5, to indicate the order of the pitches in a tune. Performance on stimuli containing correlated amplitude and duration were compared with the uni-dimensional condition. Experiment II repeated I, but required intensity to be coded. Experiment III required pitch coding under three conditions including that when amplitude and frequency were uncorrelated, and compared the performance of musically trained sunjects with nonmusicians. Experiment IV repeated III, but subjects were informed of the relation between dimensions. Experiment V involved “shadowing” the tunes by whistling simultaneously with the stimulus.

It was concluded (a) that intercorrelation improves, but zero correlation impairs short-term memory; (b) that knowledge of the relation between dimensions improves performance in the correlated condition, but does not prevent impairment under zero correlation; and (c) the performance of musically trained subjects exceeds that of controls and is unaffected by the presence of a correlated or uncorrelated dimension.     

人类镜像系统参与音乐情绪的自动加工：来自EEG的证据

大脑中线电极诱发的μ抑制波(包括α和β频段)是人类镜像系统活动的电生理指标。尽管音乐情绪表现被认为是通过模仿个体的心理状态来实现的, 但是尚未有研究探讨人类镜像系统与音乐情绪加工的关系。本研究通过EEG技术, 采用跨通道情绪启动范式, 探究人类镜像系统是否参与和弦情绪的自动加工。愉悦或不愉悦的和弦启动情绪一致与不一致的目标面孔。行为结果显示, 被试对情绪一致面孔的反应显著快于情绪不一致面孔的反应。EEG结果显示, 在听觉刺激出现后的500~650 ms之间, 与情绪一致条件相比, 情绪不一致条件诱发了β频段的去同步化。在听觉刺激出现后的300~450 ms, 无论是情绪一致, 还是不一致条件, 都诱发了α频段的去同步化。源分析结果显示, μ抑制波主要出现在人类镜像系统的相关脑区。这些结果表明, 音乐情绪的自动加工与人类镜像系统的活动密切相关。     

A comparison of generalization functions and frame of reference effects in different training paradigms

Six experiments were carried out to compare go/no-go and choice paradigms for studying the effects of intradimensional discrimination training on subsequent measures of stimulus generalization in human subjects. Specifically, the purpose was to compare the two paradigms as means of investigating generalization gradient forms and frame of reference effects. In Experiment 1, the stimulus dimension was visual intensity (brightness); in Experiment 2, it was line orientation (line-angle stimuli). After learning to respond (or to respond “right”) to stimulus value (SV) 4 and not to respond (or to respond “left”) to SV2 (in Experiment 1) or SV1 (in Experiment 2), the subjects were tested for generalization (recognition) with an asymmetrical set of values ranging from SV1 to SV11. Go/no-go training produced peaked gradients, whereas choice training produced sigmoid gradients. The asymmetrical testing resulted in a gradual shift of the peak of responding (go/no-go group) or in the point of subjective indifference (PSI; choice group) toward. the central value of the test series; thus, both paradigms revealed a frame of reference effect. The results were comparable for the quantitative (intensity) and the qualitative (line-angle) stimulus dimensions. Experiment 3 compared the go/no-go procedure with a yes/no procedure in which subjects responded “right” to SV4 and “left” to all other intensities and found no differences between these procedures. Thus the difference in gradient forms in go/no as opposed to (traditional) choice paradigms depends on whether one or two target stimuli are used in training. In Experiment 4, in which visual intensity was used, the shift in the PSI following choice training varied positively with the range of asymmetrical test stimuli employed. In Experiment 5, also with visual intensity, the magnitude of the peak shift following go/no-go training varied as a function of over representing a high or a low stimulus value during generalization testing. Experiment 6, with line angles, showed that the PSI following choice training varies in a similar way. The frame of reference effects obtained in these experiments are consistent with an adaptation-level model.     

A comparison of generalization functions and frame of reference effects in different training paradigms.

Six experiments were carried out to compare go/no-go and choice paradigms for studying the effects of intradimensional discrimination training on subsequent measures of stimulus generalization in human subjects. Specifically, the purpose was to compare the two paradigms as means of investigating generalization gradient forms and frame of reference effects. In Experiment 1, the stimulus dimension was visual intensity (brightness); in Experiment 2, it was line orientation (line-angle stimuli). After learning to respond (or to respond "right") to stimulus value (SV) 4 and not to respond (or to respond "left") to SV2 (in Experiment 1) or SV1 (in Experiment 2), the subjects were tested for generalization (recognition) with an asymmetrical set of values ranging from SV1 to SV11. Go/no-go training produced peaked gradients, whereas choice training produced sigmoid gradients. The asymmetrical testing resulted in a gradual shift of the peak of responding (go/no-go group) or in the point of subjective indifference (PSI; choice group) toward the central value of the test series; thus, both paradigms revealed a frame of reference effect. The results were comparable for the quantitative (intensity) and the qualitative (line-angle) stimulus dimensions. Experiment 3 compared the go/no-go procedure with a yes/no procedure in which subjects responded "right" to SV4 and "left" to all other intensities and found no differences between these procedures. Thus the difference in gradient forms in go/no as opposed to (traditional) choice paradigms depends on whether one or two target stimuli are used in training. In Experiment 4, in which visual intensity was used, the shift in the PSI following choice training varied positively with the range of asymmetrical test stimuli employed. In Experiment 5, also with visual intensity, the magnitude of the peak shift following go/no-go training varied as a function of overrepresenting a high or a low stimulus value during generalization testing. Experiment 6, with line angles, showed that the PSI following choice training varies in a similar way. The frame of reference effects obtained in these experiments are consistent with an adaptation-level model.     

The Effects of Intermittent Illumination on a Visual Inspection Task

Two experiments are described in which eye movements were monitored as subjects performed a simple target-spotting task under conditions of intermittent illumination produced by varying the display-screen frame rate on a computer VDU. In Experiment 1, subjects executed a saccade from a fixation point to a target which appeared randomly at a fixed eccentricity of 14 character positions to the left or right. Saccade latency did not differ reliably as a function of screen refresh rate, but average saccade extent at 70 Hz and 110 Hz was reliably shorter than at 90 Hz and 100 Hz. Experiment 2 examined the same task using a range of target eccentricities (7, 14, and 28 character positions to the left and right) and across a wider range of screen refresh rates. The results confirmed the curvilinear relationship obtained in Experiment 1, with average saccade extent reliably shorter at refresh rates of 50 Hz and 125 Hz than at 75 Hz and 100 Hz. While the effect was greater for remote targets, analyses of the proportional target error failed to show a reliable interaction between target eccentricity and display refresh rate. In contrast to Experiment 1, there was a pronounced effect of refresh rate on saccade latency (corrected for time to write the screen frame), with shorter latencies at higher refresh rates. It may be concluded that pulsation at frequencies above fusion disrupts saccade control. However, the curvilinear functional relationship between screen refresh rate and saccade extent obtained in these studies differs from previously reported effects of intermittent illumination on the average size of 'entry saccades' (the first saccade to enter a given word) in a task involving word identification (Kennedy & Murray, 1993a, 1996). This conflict of data may arise in part because withinword adjustments in viewing position, which are typical of normal reading, influence measures of average saccade extent.     

Stroboscopic visual training improves information encoding in short-term memory

The visual system has developed to transform an undifferentiated and continuous flow of information into discrete and manageable representations, and this ability rests primarily on the uninterrupted nature of the input. Here we explore the impact of altering how visual information is accumulated over time by assessing how intermittent vision influences memory retention. Previous work has shown that intermittent, or stroboscopic, visual training (i.e., practicing while only experiencing snapshots of vision) can enhance visual?Cmotor control and visual cognition, yet many questions remain unanswered about the mechanisms that are altered. In the present study, we used a partial-report memory paradigm to assess the possible changes in visual memory following training under stroboscopic conditions. In Experiment 1, the memory task was completed before and immediately after a training phase, wherein participants engaged in physical activities (e.g., playing catch) while wearing either specialized stroboscopic eyewear or transparent control eyewear. In Experiment 2, an additional group of participants underwent the same stroboscopic protocol but were delayed 24?h between training and assessment, so as to measure retention. In comparison to the control group, both stroboscopic groups (immediate and delayed retest) revealed enhanced retention of information in short-term memory, leading to better recall at longer stimulus-to-cue delays (640?C2,560?ms). These results demonstrate that training under stroboscopic conditions has the capacity to enhance some aspects of visual memory, that these faculties generalize beyond the specific tasks that were trained, and that trained improvements can be maintained for at least a day.