Influence of sensitivity on response bias in taste and audition

A detection theoretic analysis was employed to examine sensitivity and response bias in two modalities. In Experiment 1, 6 tasters made same-different judgments about the concentration of either sucrose or quinine in pairs of tonic water samples. The beverages were colored, but color was not predictive of the concentration of the sweet or bitter ingredient. When same-different ratings were collapsed to approximate the outcome of a categorical decision, tasters with poorer sensitivity appear to have adopted more extreme response criteria than did tasters with greater sensitivity, irrespective of taste quality, color, or whether pairs of solutions comprised the same or different colors. In Experiment 2, 3 individuals discriminated pairs of 1000-Hz sinusoids differing in amplitude. Six amplitude differences were tested. Rating-scale versions of two paradigms: The single-interval yes-no task and the two-interval same-different task were used to measure sensitivity and bias. There was a preponderance of "same" responses in the same-different task. Estimates of bias obtained from collapsed ratings in both tasks were unaffected by sensitivity, but a consideration of the range over which sets of criteria were spread suggested a general tendency toward more conservative response biases as sensitivity declined.     

Comparison requirements and attention in identical-nonidentical stimulus discriminations

Perceptual matching data show several puzzling effects. Particularly problematic are the disparities between the processing rates for same and different stimuli--the fast-same effect--and between the processing rates for two same-different judgment tasks that are related as mirror images--the task effect. Current models have difficulty accounting simultaneously for both effects. Central to these models is a stimulus comparison process that derives relative judgments of sameness and difference from tests of the congruence of stimulus representations. A contrasting view holds that same-different judgments can be modeled as absolute, rather than relative, judgments. This latter view is shown to be supported by experimental data. Reaction times for judgments of identical letter strings increase with string length at the same rate whether judgments are based on all the information in the strings or just the information in a single pair of component letters. The data show that stimulus comparisons of the sort described by previous models are not involved in these judgments. An attentional model accounts for the data and for the fast-same and task effects as well.     

Representations for biased numerical judgments

Models are presented that introduce bias parameters into the numerical representations for ratio and interval judgments. An interval bias model is considered that has the capability of accounting for both interval and ratio judgments. A contrasting ratio bias model—a simple generalization of the classical model that accepts ratio judgments at face value—is also considered, and both models are tested with brightness data. The ratio estimation data lead to the conclusion that the constraints placed on the structure of the data by the classical model are too strong. In terms of goodness-of-fit and certain theoretical criteria, the interval bias model accounts for the ratio estimation data better than the ratio bias model. The interval estimation data are supportive of recent efforts directed toward the development of direct interval scaling theory.     

Multidimensional scaling models for reaction times and same-different judgments

A method for joint analysis of reaction times and same-different judgments is discussed. A set of stimuli is assumed to have some parametric representation which uniquely defines dissimilarities between the stimuli. Those dissimilarities are then related to the observed reaction times and same-different judgments through a model of psychological processes. Three representation models of dissimilarities are considered, the Minkowski power distance model, the linear model, and Tversky's feature matching model. Maximum likelihood estimation procedures are developed and implemented in the form of a FORTRAN program. An example is given to illustrate the kind of analyses that can be performed by the proposed method.The work reported in this paper is supported by Grant A6394 to the first author from the Natural Sciences and Engineering Research Council of Canada. Portions of this study have been presented at the Psychometric Society meeting in Chapel Hill, N.C., in May, 1981. We thank Tony Marley, Jim Ramsay and anonymous reviewers for their helpful comments. MAXRT, a computer program which performs the computations described in this paper may be obtained by writing to the first author.     

The development of same and different judgments

Junior kindergarten children, third-grade children, and college students were given a simultaneous pattern discrimination task, with simple and complex patterns, under either unlimited or limited (150 msec) viewing time. Under unlimited viewing, RTs to same patterns were faster than to different patterns for younger children and older males. Under limited viewing, same and different RTs were equivalent, but more errors were made in judging different patterns by all age groups. The RTs were longer to complex than to simple patterns, but the increase was differentially less for the youngest Ss, especially on same pairs. Since this age difference was found under both limited and unlimited viewing, it was not attributable to age differences in perceptual scanning strategies. The same-different asymmetry in RT under unlimited viewing and in error rate under limited viewing confirms across a wide age range previous findings with adults using codable stimuli. A two-process model for same and different judgments appears to be required, although young children may have had a response bias for same in Expt II.     

The relative sensitivities of same-different and identification judgment models to perceptual dependence

Probabilistic models of same-different and identification judgments are compared (within each paradigm) with regard to their sensitivity to perceptual dependence or the degree to which the underlying psychological dimensions are correlated. Three same-different judgment models are compared. One is a step function or decision bound model and the other two are probabilistic variants of a similarity model proposed by Shepard. Three types of identification models are compared: decision bound models, a probabilistic multidimensional scaling model, and probabilistic models based on the Shepard-Luce choice rule. The decision bound models were found to be most sensitive to perceptual dependence, especially when there is considerable distributional overlap. The same-different model based on the city-block metric and an exponential decay similarity function, and the corresponding identification model were found to be particularly insensitive to perceptual dependence. These results suggest that if a Shepard-type similarity function accurately describes behavior, then under typical experimental conditions it should be difficult to see the effects of perceptual dependence. This result provides strong support for a perceptualindependence assumption when using these models. These theoretical results may also play an important role in studying different decision rules employed at different stages of identification training.We thank Robert Melara, Jerome Busemeyer and three anonymous reviewers for comments on an earlier draft of this paper.     

异同判断中“快同效应”的大脑机制：一项ERP研究

采用高密度的事件相关电位（ERPs）技术,记录分析了大学生被试在执行异同判断任务[包括不同颜色刺激对（DC）,不同形状刺激对（DS）和相同刺激对（Same）]时的脑内时程动态变化。行为结果表明,“同”反应的确显著快于“异”反应,表现出明显的快同效应。ERP结果显示：在280-320 ms内,DS和DC条件均比Same条件诱发一个更负的N2成分。偶极子溯源分析表明,DC和DS条件下,N2可能起源于大脑的前扣带皮层（ACC）,可能与“异”反应早期不一致信息（颜色或形状）的认知监控和调节有关;反之Same条件下,N2成分可能起源于楔前叶,主要反映了“同”反应早期知觉识别中整体特征比较加工的过程（同一性指示器）。另外,在450 ms左右, DC和DS比Same条件均诱发了一个更负的P3成分,可能反映了对刺激局部特征的比较和识别（慢速比较器）,并与选择性注意和资源分配等高级认知活动有关;并且,Same条件下P3成分的潜伏期更短,与行为结果一致。以上研究结果表明,异同判断中“同”反应和“异”反应可能有着不同的比较通道和大脑机制,支持双过程模型理论;同时表明,慢速比较器和同一性指示器可能是序列加工的。     

Isolating visual units in the perception of words and nonwords

In three experiments, reaction times for same-different judgments were obtained for pairs of words, pronounceable nonwords (pseudowords), and unpronounceable nonwords. The stimulus strings were printed either in a single letter case or in one of several mixtures of upper- and lowercase letters. In Experiment 1, the stimuli were common one- and two-syllable words; in Experiment 2, the stimuli included both words and pseudowords; and in Experiment 3, words, pseudowords, and nonwords were used. The functional visual units for each string type were inferred from the effects that the number and placement of letter case transitions had onsame reaction time judgments. The evidence indicated a preference to encode strings in terms of multiletter perceptual units if they are present in the string. The data .also suggested that whole words can be used as functional visual units, although the extent of their use depends on contextual parameters such as knowledge that a word will be presented.     

Indices of response bias in the same-different experiment

The same-different experiment is popular for assessing perceptual performance, including the performance of people with neuropsychological deficits. Although the measurement of accuracy with this experiment is now well understood, the measurement of response bias remains problematic. Reformulating the decision space for the experiment can yield new bias indices that are analogous to, but numerically different from, those of the more familiar yes-no experiment. Isobias curves that show how hit rate covaries with false alarm rate for constant bias but varying accuracy are presented for eight indices, and best-fitting parameters of the isobias functions are determined for a set of experimental data. The theoretical status of the bias indices and their relation to other formulations are reviewed.     

The effects of familiarity in a perceptual matching task

Latencies of same-different judgments to pairs of two-digit numerals were recorded for stimuli presented in familiar or unfamiliar (inverted) orientation. Familiar stimuli were responded to more quickly than unfamiliar. For both stimulus types, latencies were correlated with the syllable length of the verbal representation of the numerals, allowing the interpretation that the effect of stimulus orientation is on encoding processes. In two other experiments, it was found that familiarity had no effect on different judgments when the stimuli were relatively simple (e.g., a single digit), but did affect different judgments with more complex stimuli. These results were related to the hypothesis that the complexity of verbal material determines whether different judgments are instigated by visual or by verbal representations of the stimuli.     

Cross-category structure in semantic memory

In Experiment I, subjects made similarity judgments about all 56 category terms listed in the Battig and Montague (1969) norms. These judgments were then subjected to a hierarchical clustering analysis. Experiment II demonstrated that the relations among the category labels are very similar to the relations among the high dominance exemplars of these categories. Experiment III showed that the distances between the category terms in the hierarchical clustering analysis could predict RTs in a same-different paradigm.     

Children judge "perspective" transformations of letterlike forms as different from prototypes

Children from 5 to 11 years old made same-different judgments of prototypes of letterlike forms paired with transforms of these prototypes generated on a dimension either critical or noncritical for object identification. For compression transformations (noncritical: as in perspective shift), frequency of correct “different” judgments increased as the degree of compression in the transform increased. This result challenges the view that dimensions irrelevant in object identification are ignored or not detected in graphic discrimination.     

How framing statistical statements affects subjective veracity: Validation and application of a multinomial model for judgments of truth

Extending the well-established negativity bias in human cognition to truth judgments, it was recently shown that negatively framed statistical statements are more likely to be considered true than formally equivalent statements framed positively. However, the underlying processes responsible for this effect are insufficiently understood. Therefore, a multinomial processing tree model is herein proposed to distinguish between differences in (a) knowledge or (b) response bias that may account for the framing effect. Three model validation experiments supported the psychological interpretability of model parameters. Model application revealed that the framing effect can be considered a bias: Given insufficient knowledge, individuals more likely guessed "true" when faced with a negatively framed statistical statement. The probability of conclusive knowledge, however, remained constant across frames. In summary, this article puts forwards and validates a formal model that can be used more generally to investigate processes underlying truth judgments. Based on this model, it is herein shown that one particular phenomenon - framing effects observed for statistical statements - can be considered a response bias, rather than the upshot of differential knowledge.     

Mental size scaling examined

Observers made same-different shape judgments of stimuli that were identical in shape and size different in shape but not in size, or differed in relative size along a number of steps for both same- and different- shaped forms. "Same" judgment RTs increased monotonically with increases in the magnitude of the relative size difference. In contrast, "different" judgment RTs were unaffected by changes in relative size. A second experiment in which stimulus presentation was successive rather than simultaneous yielded essentially the same results. Consideration was given to a dual- process model in which a time-consuming analog process normalizes stimuli that are size discrepant prior to a comparison stage that is operative for those structures responsible for "same" decisions but not for "different" judgments. Some evidence that seems inconsistent with a normalization process which operates prior to contact with memory was discussed, and an alternative explanation in which the early detection of a size difference causes changes in decision criteria was suggested.     

The “ventriloquist effect”: Visual dominance or response bias?

The interaction between vision and audition was investigated using a signal detection method. A light and tone were presented either in the same location or in different locations along the horizontal plane, and the subjects responded with same-different judgments of stimulus location. Three modes of stimulus presentation were used: simultaneous presentation of the light and tone, tone first, and light first. For the latter two conditions, the interstimulus interval was either 0.7 or 2.0 sec. A statistical decision model was developed which distinguished between the perceptual and decision processes. The results analyzed within the framework of this model suggested that the apparent interaction between vision and audition is due to shifts in decision criteria rather than perceptual change.     

Functional equivalence between same-different classifications and judged similarity of Markov patterns

This experiment represented an initial at tempt at comparing same-different classifications and similarity judgments of Markov histoforms sampled from three different schema families. A measure of individual stimulus variability was more strongfy related to classification responses than to judged similarity. Dichotomous responses, derived from the similarity data by imposing threshold criteria, were found to be highly similor to real classification responses when the threshold values were estimated directly from the latter; little correspondence, however, was obtained using optimal classification criteria. The results support the notion that somewhat different features are used in making classification responses and similarity judgments, and indicate the need for developing more sensitive tasks involving controlled scanning of pattem information.     

Memory for targets in a multilevel simulated environment: Evidence for vertical asymmetry in spatial memory

In two experiments, adult participants explored a symmetrical three-tiered computer-simulated building that contained six distinctive objects, two on each floor. Following exploration, the objects were removed, and the participants were asked to make direction judgments from each floor, indicating the former positions of the objects on that floor and on higher and lower floors. Relative tilt error scores indicated a bias, in that targets that were higher than the test location were judged as consistently lower than their actual positions and targets that were lower than the test location were judged as consistently higher than their actual positions. Absolute tilt errors revealed an asymmetry, with more accurate and less variable tilt errors for judgments directed to lower floors than for judgments directed to higher floors. Experiment 3 ruled out an account of the findings that does not relate them to spatial memory. The results suggest that the superiority of downward over upward spatial judgments, previously reported in two-dimensional visual-spatial tasks, extends to navigational spatial memory.     

The truth and bias model of judgment

We present a new model for the general study of how the truth and biases affect human judgment. In the truth and bias model, judgments about the world are pulled by 2 primary forces, the truth force and the bias force, and these 2 forces are interrelated. The truth and bias model differentiates force and value, where the force is the strength of the attraction and the value is the location toward which the judgment is attracted. The model also makes a formal theoretical distinction between bias and moderator variables. Two major classes of biases are discussed: biases that are measured with variables (e.g., assumed similarity) and directional bias, which refers to the extent to which judgments are pulled toward 1 end of the judgment continuum. Moderator variables are conceptualized as variables that affect the accuracy and bias forces but that do not affect judgments directly. We illustrate the model with 4 examples. We discuss the theoretical, empirical, methodological, measurement, and design implications of the model.     

Hemispatial asymmetries in judgment of stimulus size

Recent research has demonstrated a leftward bias in judgments of size. In the present experiments, hemispatial size bias was measured through simultaneous presentation of a circle and an ellipse varying in horizontal or vertical extent. A consistent leftward bias of horizontal size judgments (but not vertical) was obtained; at the point of subjective equality, the width of the objects that were presented in left hemispace was smaller than the width of the objects that were presented in right hemispace. These data suggest that the horizontal extent of stimuli appear larger in left hemispace than in right hemispace. Results also indicated that symmetrical stimulus presentation, with respect to the vertical meridian, is required for the bias to emerge. Furthermore, increasing or decreasing stimulus eccentricity weakened the effect. Attenuation of this bias upon the manipulation of parameters indicates that this phenomenon is context specific and is affected by similar parameters that are known to influence the magnitude of error in pseudoneglect.     

The edge complex: implicit memory for figure assignment in shape perception

Viewing a stepped edge is likely to prompt the perceptual assignment of one side of the edge as figure. This study demonstrates that even a single brief glance at a novel edge gives rise to an implicit memory regarding which side was seen as figure; this edge complex enters into the figure assignment process the next time the edge is encountered, both speeding same-different judgments when the figural side is repeated and slowing these judgments when the new figural side is identical to the former ground side (Experiments 1A and 1B). These results were obtained even when the facing direction of the repeated edge was mirror reversed (Experiment 2). This study shows that implicit measures can reveal the effects of past experience on figure assignment, following a single prior exposure to a novel shape, and supports a competitive model of figure assignment in which past experience serves as one of many figural cues.