An interval scale of saturation for the pigeon

Pigeons were required to discriminate between “identical” vs. “different” pairs of lights in a yes/no signal-detection task with a symmetrical payoff matrix. If the two lights projected on the two halves of the bipartite field constituting the center response key in a three-key chamber were identical in wavelength composition, then a single peck on the left key was reinforced with food. If the two lights differed in wavelength composition, then right-key pecks were reinforced. Each pigeon experienced all possible pairs (55) of 11 lights having the same dominant hue (630 nm) but differing in colorimetric purity. The percentage of correct responses was taken as a measure of the dissimilarity between the two lights constituting a pair. The rank-order information available in these dissimilarity measures was used to determine an interval scale of saturation in the pigeon. Saturation was found to be linearly related to colorimetric purity.     

The pigeon's perception of saturation.

Three experiments used similar methods to investigate the pigeon's perception of saturation of monochromatic lights. This trial-wise procedure consisted of brief presentations of positive and negative stimuli in random sequence. Pecks to the positive stimuli were occasionally reinforced on a low fixed-ratio schedule. The first study determined absolute thresholds for "white" and monochromatic lights by establishing a discrimination between lights of various radiances and a dark key. Experiment II investigated generalization from a white light to various monochromatic lights under conditions that minimized the use of luminance as a cue. The third experiment examined discrimination of various monochromatic lights along a colorimetric purity continuum; responses to white light were reinforced, while responses to lights that combined white and monochromatic lights in various proportions were not. The results indicated that lights of different wavelength differ in saturation, but that all are discriminable from white. Wavelengths between 550 and 600 nm are least saturated for the pigeon, and saturation increases markedly as wavelength decreases below this region of the spectrum.     

The influence of ultraviolet radiation on the pigeon's color discrimination

Two experiments demonstrated the pigeon's sensitivity to ultraviolet light. In Experiment I, pigeons' responses were reinforced on a multiple schedule with a variable-interval reinforcement schedule in one component and extinction in the other component. Response rates were quite different in the two components where the 520-nm stimuli signalling each component differed only in that one of them contained a 366-nm ultraviolet component. In Experiment II, pigeons were trained to peck one side key when two halves of a split field were of different wavelength and to peck another side key when they were of the same wavelength. Initially, field halves contained both "visible" and ultraviolet components of energy. Discrimination performance improved when the ultraviolet component was removed from one field half. It was argued that the critical change in the stimulus was a color change, rather than a brightness one, or a fluorescence of structures in the pigeon's eye.     

Dissimilarities as indices of individual perceptual structure

The generality of dissimilarity judgments and of configurations obtained by multidimensional scaling (MDS) as indices of perceptual structure was examined. The Ss made magnitude estimates of dissimilarity of pairs of photos, and MDS configurations were constructed separately for each S. The compatability of dissimilarities (judgments or distances in MDS configurations) with two other tasks Ss performed was then examined. These additional tasks, an “encoding” and a “decoding” task, required the S to first construct a message by making use of a set of four photos and, a week later, to decode the messages. Results obtained were interpreted as indicating a degree of generality of the dissimilarities and supporting a hypothesis of individual differences in perceptual structure for the stimulus set. A “data-purification” hypothesis for MDS was discussed and examined.

     

Delayed signal detection, differential reinforcement, and short-term memory in the pigeon.

In two discrete-trial delayed-detection experiments, six pigeons were trained on dependent concurrent variable-interval schedules. Pecking a red side key was reinforced when the brighter of two white lights (S1) had been presented on the center key, and pecking a green side key was reinforced when the duller of two white lights (S2) had been presented on the center key. Incorrect responses were red side-key pecks following S2 presentations and green side-key pecks following S1 presentations; these resulted in three-second blackouts. In Experiment 1, the time between presentation of S1 or S2 on the center key and the onset of the red and green side keys was varied nonsystematically from 0.06 seconds to 19.69 seconds across experimental conditions. Stimulus discriminability decreased as the stimulus-choice delay increased. A rectangular-hyperbolic function better described this decrease in discriminability over time than did a negative-exponential function. In Experiment 2, at each of three stimulus-choice delays (0.06, 3.85, and 10.36 seconds), relative reinforcer frequency for correct responses to the red and green side keys was varied by changing the values of the dependent concurrent variable-interval schedules. The sensitivity of choice to relative reinforcer frequency was independent of the decrease in stimulus discriminability with increasing stimulus-choice delay.     

Effects of a brief stimulus accompanying reinforcement on instrumental responding in pigeons

The responding of pigeons on a variable interval schedule of reinforcement was investigated in four experiments. In some conditions in each experiment reinforced keypecks were accompanied by a brief (0.5-sec) flash of the houselight. This procedure resulted in a low rate of response in comparison with that found in conditions when response-contingent light flashes occurred uncorrelated with reinforcement (Experiments 1 and 2) or when no light flash was presented (Experiment 3). Experiment 4 allowed a comparison between the effects of a signal accompanying the reinforced response and one accompanying the delivery of “free” food. Signaling the delivery of earned food produced a lower rate of response than did signaling the delivery of free food. The role of stimulus-reinforcer and response-reinforcer associations in producing these effects is discussed.     

The effect of location on the discrimination of spatial vibrotactile patterns

The present study examined whether the locations of patterns on the skin affected the ability to process information about their shapes. In Experiment 1, pairs of spatial vibrotactile patterns, using the array from the Optacon, were presented sequentially to subjects’ left index fingerpads. The location of each pattern in a pair was varied randomly among four locations on the skin. The subjects responded “same” or “different” on the basis of the shapes of patterns, regardless of their locations. Discrimination accuracy was highest and response time fastest when patterns occupied identical locations (ILs), and performance suffered with increasing distance between patterns. In Experiment 2, pairs were presented to corresponding points or to noncorresponding points on separate fingerpads. When patterns occupied corresponding points on separate fingers, accuracy was lower than when patterns occupied ILs on a single finger, but higher than when patterns occupied noncorresponding points on separate fingers. The results suggested that discriminability declined partly because patterns did not occupy ILs, and partly because separate locations had different densities of innervation.     

反应选项对时序知觉重复启动效应的影响

先前研究采用两项反应任务发现了时序知觉重复启动效应, 这可能是反应选项导致的虚假效应, 本研究采用三项反应任务对此进行了检验。实验1运用三项判断任务以消除缺乏中间选项所致的反应偏向, 结果发现重复启动显著影响“哪个图形先出现”和“两个图形同时出现”的时序判断; 实验2在实验1的基础上对“同时出现”反应选项进行两种指导语操作, 实验结果不仅与实验1一致, 而且“有把握时判断为同时出现”和“有无把握都判断为同时出现”之间没有显著差异, 说明被试能够识别时序加以判断, 不支持反应偏向的前提条件。因此, 时序知觉重复启动效应不是反应选项产生的反应偏向引发的虚假效应, 重复启动对“系列性”和“同时性”时序知觉都存在显著影响。     

DO CONDITIONAL REINFORCERS COUNT?

Six pigeons were trained on a procedure in which seven components arranged different food-delivery ratios on concurrent variable-interval schedules each session. The components were unsignaled, lasted for 10 food deliveries, and occurred in random order with a 60-s blackout between components. The schedules were arranged using a switching-key procedure in which two responses on a center key changed the schedules and associated stimuli on two side keys. In Experiment 1, over five conditions, an increasing proportion of food deliveries accompanied by a magazine light was replaced with the presentation of the magazine light only. Local analyses of preference showed preference pulses toward the alternative that had just produced either a food-plus-magazine-light or magazine-light-only presentation, but pulses after food deliveries were always greater than those after magazine lights. Increasing proportions of magazine lights did not change the size of preference pulses after food or magazine-light presentations. Experiment 2 investigated the effects of correlations between food ratios and magazine-light ratios: In Condition 6, magazine-light ratios in components were inversely correlated (-1.0) with food ratios, and in Condition 7, magazine-light ratios were uncorrelated with food ratios. In Conditions 8 and 9, pecks also produced occasional 2.5-s flashes of a green keylight. In Condition 8, food and magazine-light ratios were correlated 1.0 whereas food and green-key ratios were correlated -1.0. In Condition 9, food and green-key ratios were correlated 1.0 whereas food and magazine-light ratios were correlated -1.0. Preference pulses toward alternatives after magazine lights and green keys depended on the correlation between these event ratios and the food ratios: If the ratios were correlated +1.0, positive preference pulses resulted; if the correlation was -1.0, preference pulses were negative. These results suggest that the Law of Effect has more to do with events signaling consequences than with strengthening responses.     

Shuffling your way out of change blindness

Change detection is typically discussed in the literature as a 2-state phenomenon. Small differences between otherwise identical images are easy to detect when the images are superimposed in space and alternated in time (“shuffled”). However, change blindness results from any disruption that prevents the critical change from generating the sole salient transient. Here we show that different presentation strategies produce different degrees of change blindness for the same change. Specifically, shuffling the images supports faster change detection than viewing the same 2 images side by side, even when the images contain a number of distracting differences. In Experiment 1, pairs of photographs having a 50 % chance of containing a difference were viewed either in alternation, in a “Shuffle” condition, or simultaneously, in a “Side-by-Side” condition. Change detection was about 6 seconds faster when the images were viewed in the “Shuffle” mode. In Experiment 2, we presented two images that were slightly laterally shifted relative to each other (0–48 pixels). The RT benefit for the Shuffle viewing mode was very strong when the relative shift was small, to insignificant when there was a large difference between the two images. However, at large shifts, Shuffle maintained an accuracy advantage. It seems that changes are easier to detect when comparing images in a Shuffle condition rather than Side-by-Side. This has important implications for real world tasks like radiology where detection of change is critical.     

A RUNS‐TEST ALGORITHM: CONTINGENT REINFORCEMENT AND RESPONSE RUN STRUCTURES

Four rats' choices between two levers were differentially reinforced using a runs‐test algorithm. On each trial, a runs‐test score was calculated based on the last 20 choices. In Experiment 1, the onset of stimulus lights cued when the runs score was smaller than criterion. Following cuing, the correct choice was occasionally reinforced with food, and the incorrect choice resulted in a blackout. Results indicated that this contingency reduced sequential dependencies among successive choice responses. With one exception, subjects' choice rule was well described as biased coin flipping. In Experiment 2, cuing was removed and the reinforcement criterion was changed to a percentile score based on the last 20 reinforced responses. The results replicated those of Experiment 1 in successfully eliminating first‐order dependencies in all subjects. For 2 subjects, choice allocation was approximately consistent with nonbiased coin flipping. These results suggest that sequential dependencies may be a function of reinforcement contingency.     

Luminance thresholds for the Bezold-Brücke hue shift

This study presents data on the luminance difference at which a hue difference is first perceived between two identical spectral lights. Thresholds were obtained for both luminance increments and decrements from a 2.00 log troland standard for wavelengths between 470 nm and 690 nm. A predicted luminance threshold for each wavelength was calculated based on wavelength discrimination data and the Purdy constant hue contours; i.e. that luminance at which the constant hue contour intersects the wavelength discrimination bound for a given wavelength. A generally good agreement was obtained between observed and predicted values.     

Children’s developing understanding of the relation between variable causal efficacy and mechanistic complexity

Two experiments investigated 3–4-year-olds’ ability to infer the causal mechanisms for a pair of lights. In both experiments the exterior of the two lights appeared identical. In Experiment 1, one light displayed a stable activation pattern of a single color while the other light displayed a variable pattern of activation by cycling through a series of different colors (i.e., a more varied effect). Children were asked to judge which light had a more complex internal structure. Four-year-olds were more likely to match the light with the more variable effect with a more complex internal mechanism and the light with the more stable effect with a less complex mechanism. Three-year-olds’ responses were at chance. Experiment 2 replicated this finding when the activation patterns of the two lights were described verbally but never demonstrated. Taken together, these results suggest that 4-year-olds appreciate that the variability of an object’s causal efficacy is related to the complexity of its internal mechanistic structure.     

Laterality effects in perceptual matching

Two experiments are reported in which Ss had to indicate whether pairs of simple geometric forms were “same” or “different.” In Experiment I the two forms were either both in the left visual hemifield or both in the right hemifield. Reaction times were unaffected by the locus of the stimuli. In Experiment 2, in addition to left and right pairs, there were pairs in which one of the stimuli was on the left and the other was on the right. Under these conditions, reaction times were faster for pairs totally on the left than for pairs totally on the right. The data support the notion that implicit scanning patterns are important in determining laterality differences. When such scanning is not involved and when simple nonverbal stimuli and responses are employed, laterality differences are eliminated.     

Discrimination of structure: I. Implications for connectionist theories of discrimination learning

In each of 4 experiments animals were given a structural discrimination task that involved visual patterns composed of identical features, but the spatial relations among the features were different for reinforced and nonreinforced trials. In Experiment 1 the stimuli were pairs of colored circles, and pigeons were required to discriminate between patterns that were the mirror image of each other. A related task was given to rats in Experiment 2. Subjects solved these discriminations. For Experiment 3, some pigeons were given a discrimination similar to that used in Experiment 1, which they solved, whereas others received a comparable task but with 3 colored circles present on every trial, which they failed to solve. The findings from Experiment 3 were replicated in Experiment 4 using different patterns. The results are difficult to explain by certain connectionist theories of discrimination learning, unless they are modified to take account of the way in which compound stimuli are structured.     

Search for a matching or mismatching letter pair

The perceptual matching task was modified in order to increase the error rate and thus to reveal more clearly whether internal noise more often changes an objective match into a perceived mismatch than vice versa (noisy-operator theory). In Experiment 1, subjects searched for a “same” pair in a list of “different” pairs or for a “different” pair in a list of “same” pairs. As predicted, the target pair was overlooked or missed more often on “different” lists. False alarms, though, were not higher on “same” lists, owing apparently to rechecking, which also produced slower search through “different” lists. To disable the rechecking mechanism, rapid serial visual presentation (RSVP) was used in Experiments 2 and 3. As predicted, misses exceeded false alarms on “different” lists, whereas the reverse held on “same” lists, both at the physical level (Experiment 2) and at the name level (Experiment 3). Letter set size and repetition were varied in Experiments 1 and 2, and the results indicate that when letter pairs are presented in close temporal and spatial proximity, subjects are influenced by extraneous interpair comparisons in addition to relevant intrapair comparisons in deciding whether or not a target pair is present.     

Loudness “ratios” and “differences” involve the same psychophysical operation

Subjects judged both “atios” of loudness and “differences” in loudness between pairs of tones that varied in intensity. The pairs were constructed from factorial designs, permitting separation of stimulus and response scaling for each subject. Ratings of “differences” and estimations of “ratios” were monotonically related, inconsistent with the hypothesis that subjects perform both subtractive and ratio operations on a common scale. Instead, the data suggest that both tasks involve the same psychophysical comparison operation with different response transformations. If the operation can be represented by the subtractive model, then category ratings involve a nearly linear transformation and magnitude estimations involve a nearly exponential transformation.     

Memorization and “feature selection” in the acquisition of natural concepts in pigeons

Pigeons were trained on a successive discrimination task using complex visual stimuli. In Experiment 1, each photographic slide that contained a person had a corresponding “matched background” slide, one that showed the same scene with the person removed. Birds trained on a human positive discrimination acquired the matched pairs problem, but birds trained on a human negative discrimination performed poorly. This suggests a feature-positive effect for complex stimulus categories. Memorization control groups that were trained on a human-irrelevant discrimination also performed poorly with matched slides. However, subsequent experiments demonstrated that these effects depended on the use of matched pairs of slides. The human-as-feature effect was not obtained when human positive and human negative groups were subsequently trained with non-matched slides (Experiment 2), and memorization control groups acquired a human-irrelevant discrimination when trained with nonmatched slides (Experiment 3). Additional tests conducted in Experiments 2 and 3 found that performance was not disrupted when either the reinforced or nonreinforced slides were replaced. This effect was obtained when the category was relevant to the discrimination (Experiment 2) and when the category was irrelevant to the discrimination (Experiment 3). Finally, Experiment 4 demonstrated that memorization of a set of slides is possible when slides are sufficiently dissimilar, (i.e., nonmatched) but performance is not as good when the category exemplars are irrelevant to the discrimination.     

Processing of locatives “in,” “on,” and “under” by aphasic patients: An analysis of the regression hypothesis

The present study investigated the comprehension of aphasic subjects as to locative prepositions “in,” “on,” and “under.” Patients had to locate a movable object with reference to a stationary referential object in order to achieve the spatial relations requested under oral instructions. The influence of two types of contextual relations between the objects in each stimulus pair on the subjects' performances was examined. Spatial relations were biased by the conventional knowledge of the most normal relationship between the two elements in everyday life in Experiment 1; in Experiment 2, perceptivomotor constraints constituted the contextual bias. Analyzing the patients' responses in the light of developmental strategies did not lend support to the regression hypothesis. Broca's aphasics were sensitive to the two contextual factors investigated; Wernickes' performances were affected only by the perceptivomotor contextual bias. The results are discussed with reference to earlier studies on the differential syntactical comprehension skills of Broca's and Wernicke's aphasics in sentence-picture matching tasks and production tasks.     

Semantic and spatial factors in environmental memory

Reaction time (RT) in simple categorization tasks was predicted to vary as a function of the relatedness among environmental items. Differences in RT were interpreted as reflecting differences in proximity or strength of associations in environmental memory. In Experiment 1, subjects sorted names of familiar local buildings according to which seemed to go together. Hierarchical cluster analysis revealed major clusters whose members were related in function and, within these, smaller clusters of buildings related by spatial proximity. In Experiment 2, subjects responded “Yes” if two items on a trial were both local buildings and “No” if one item was local and one nonlocal. Subjects responded significantly faster to pairs taken from the cluster analysis that were related by both spatial proximity and function than they did to unrelated pairs or pairs related in function only. In Experiment 3, a free-associaton task identified related pairs of spatially proximate, functionally dissimilar environmental items. In Experiment 4, RTs to these pairs did not differ from RTs to pairs of spatially proximate, functionally dissimilar items or from RTs to pairs unrelated functionally and spatially. Spatial proximity and functional similarity together contribute to the organization in memory of buildings in the physical environment.