Response system processes in absolute judgment

Consistent relationships are found between Ss′ absolute judgments of the value of a stimulus and the previous sequence of both stimuli and responses. The form and magnitude of these sequential effects are shown to depend on the presence or absence of feedback and on task difficulty. The pattern of the sequential effects found allows the conclusion that they are due to purely response-system processes. A two-stage model of the judgment process is proposed, and it is argued that observed assimilative effects account for the central tendency effects observed in category judgments.     

Pictorial and verbal encoding in a short-term memory task

The present research attempted to manipulate the encoding modality, pictorial or verbal, of schematic faces with well-learned names by manipulating S’s expectations of the way the material was to be used. On every trial, a single name or face was presented, followed by another one; the S was asked to respond “same” if the stimuli had the same name, and “different” otherwise. The majority of second stimuli of any session was either names or faces. It was hypothesized that if S had encoded the first stimulus in the modality of the second, his judgment would be faster than if he had not appropriately encoded the first stimulus. Significantly slower reaction times were obtained to stimulus pairs where the second stimulus modality was infrequent. Further evidence that encoding of the first stimulus was in the frequent second stimulus modality comes from the finding that “different” responses were shorter when the stimuli differed on more than one attribute in the encoding (second stimulus) modality, regardless of the modality of the stimuli. Thus, evidence is presented that not only can verbal material be pictorially encoded (and vice versa), but that whether either verbal or pictorial material is verbally or pictorially encoded depends on S’s anticipation of what he is to do with the material.     

The role of preparation and cue-modality in crossmodal task switching

The present study examined the effects of cue-based preparation and cue-target modality mapping in crossmodal task switching. In two experiments, we randomly presented lateralized visual and auditory stimuli simultaneously. Subjects were asked to make a left/right judgment for a stimulus in only one of the modalities. Prior to each trial, the relevant stimulus modality was indicated by a visual or auditory cue. The cueing interval was manipulated to examine preparation. In Experiment 1, we used a corresponding mapping of cue-modality and stimulus modality, whereas in Experiment 2 the mapping of cue and stimulus modalities was reversed. We found reduced modality-switch costs with a long cueing interval, showing that attention shifts to stimulus modalities can be prepared, irrespective of cue-target modality mapping. We conclude that perceptual processing in crossmodal switching can be biased in a preparatory way towards task-relevant stimulus modalities.     

Range effects in successive discrimination

In two sets of experiments we examined pigeons' discrimination performance with a visual flicker-rate continuum, using a conventional successive discrimination procedure. In the first experiment, responses during the intermediate stimulus value were never reinforced, while responses during stimuli on either end of the continuum were reinforced periodically. In the second experiment, responses during stimuli from one end of the continuum were never reinforced, while responses during stimuli from the other end of the continuum were reinforced periodically. Results from both experiments show that discrimination between unchanged positive and negative stimulus values is a function of the range over which the total stimulus set varies. These range effects are comparable to effects found in absolute judgment tasks in human and animal psychophysics. In addition, the range effects reported here are not due to channel capacity, but may depend instead on variability in judgment criteria.     

Higher order sequential effects in psychophysical judgments

We found that the depth of sequential effects depends on the judgment task. An experiment with squares indicated that stimulus-response pairs up to two trials back were included in the judgment process when subjects were required to make category judgments of size, whereas only the immediately preceding event was incorporated when subjects were making magnitude estimations. In the case of category judgment, interactions between the current stimulus and prior stimuli as well as configural effects indicated that events one and two trials back meet an equivalent function in the judgment process and that these events may jointly operate in one trial. These findings can be explained by a class of models that assume that the position of preceding stimuli relative to the current stimulus is decisive in the judgment process. The multiple-standards model is a representative of this class according to which there are two types of standards: (1) the endpoints of the range as long-term standards and (2) traces of preceding stimuli as short-term standards.     

Higher order sequential effects in psychophysical judgments

We found that the depth of sequential effects depends on the judgment task. An experiment with squares indicated that stimulus-response pairs up to two trials back were included in the judgment process when subjects were required to make category judgments of size, whereas only the immediately preceding event was incorporated when subjects were making magnitude estimations. In the case of category judgment, interactions between the current stimulus and prior stimuli as well as configural effects indicated that events one and two trials back meet an equivalent function in the judgment process and that these events may jointly operate in one trial. These findings can be explained by a class of models that assume that the position of preceding stimuli relative to the current stimulus is decisive in the judgment process. The multiple-standards model is a representative of this class according to which there are two types of standards: (1) the endpoints of the range as long-term standards and (2) traces of preceding stimuli as short-term standards.     

Sequential effects in face-attractiveness judgment

A number of studies have shown that current-trial responses are biased toward the response of the preceding trial in perceptual decisionmaking tasks (the sequential effect-Holland and Lockhead, 1968 Perception & Psychophysics 3 409-414). The sequential effect has been widely observed in evaluation of the physical properties of stimuli as well as more complex properties. However, it is unclear whether subjective decisions (e.g., attractiveness judgments) are also susceptible to the sequential effect. Here, we examined whether the sequential effect would occur in face-attractiveness judgments. Forty-eight pictures of male and female faces were presented successively. Participants rated the attractiveness of each face on a 7-point scale. The results showed that the attractiveness rating of a given face assimilated toward the rating of the preceding trial. In a separate experiment, we provided the average attractiveness rating by others for each trial as feedback. The feedback weakened the sequential effect. These findings suggest that attractiveness judgment is also biased toward the preceding judgment, and hence the sequential effect can be extended into the domain of subjective decisionmaking.     

The influence of category membership of stimuli on sequential effects in magnitude judgment

The present study addresses the problem of whether range effects and sequential dependencies are affected by stimulus category membership in the same way. Two sets of squares differing in color were presented to subjects. The subjects were asked to judge them according to size, under two instructions. The separation instruction required them to judge each square solely in relation to its own category. The integration instruction required them to ignore category membership. The results indicated that, under the separation instruction, the range effects, as well as the sequence effects, confined themselves to stimuli of the same category. Under the integration instruction, however, the squares were judged in relation to the range of all the stimuli, and sequential effects were independent of the stimulus category. This parallel trend in the category-specific effects of range and preceding stimuli was found for judgments, as well as for reaction times. The findings are discussed with regard to models of sequential effects.     

Stimulus spacing effects in duration perception are larger for auditory stimuli: Data and a model

Models of duration bisection have focused on the effects of stimulus spacing and stimulus modality. However, interactions between stimulus spacing and stimulus modality have not been examined systematically. Two duration bisection experiments that address this issue are reported. Experiment 1 showed that stimulus spacing influenced the classification of auditory, but not visual, stimuli. Experiment 2 used a wider stimulus range, and showed stimulus spacing effects for both visual and auditory stimuli, although the effects were larger for auditory stimuli. A version of Temporal Range Frequency Theory was applied to the data, and was used to demonstrate that the qualitative pattern of results can be captured with the single assumption that the durations of visual stimuli are less discriminable from one another than are the durations of auditory stimuli.     

Stimulus-specific processing consequences of pattern goodness

Two issues concerning the effects of visual pattern goodness on information processing time were investigated: the role of memory vs. encoding and the role of individual stimulus goodness vs. stimulus similarity. A sequential “same-different” task was used to provide differentiation of target item or memory effects from display item or encoding effects. Experiment 1 used four alternative stimuli in each block of trials. The results showed that good patterns were processed faster than poor patterns for both “same” and “different” responses. Furthermore, the goodness of the target item had a greater effect on reaction time than did the goodness of the display item, indicating that memory is more important than encoding in producing faster processing of good stimuli. Effects of interstimulus similarity on processing time were minimal, although isolation of good stimuli in a similarity space could explain many of the results. Experiment 2 replicated the results of Experiment 1, despite the fact that differences in similarity space had been minimized by using only two alternative stimuli in each block. In addition, the speed of processing a “same” pair was essentially independent of the particular alternative stimulus in a block. These results suggest that in this task, there is a processing advantage for good stimuli that is stimulus specific, with the effect operating primarily in memory.     

Mixed-modality psychophysical scaling: Double cross-modality matching for “difficult” continua

In mixed-modality psychophysical scaling, stimuli from different modalities are presented alternately for judgment on the same scale. The usual purpose is to produce cross-modality matching functions without actually doing cross-modality matches. This paper reports the results of two experiments that extend the method to situations in which the responses, themselves crossmodality matches on an easy-to-control continuum (duration), are used to derive matching functions for two difficult-to-control continua (here loudness and brightness). Derived cross-modality matching functions are highly similar to those obtained from magnitude estimation or category judgment responses. First- and second-order sequential dependencies also closely resemble those found in data from the methods that employ numerical response scales, with one exception. For the first time in these studies of mixed-modality scaling, current responses sometimes were found to be weakly contrasted to the values of previous stimuli of different modality from the current stimulus. The various sequential dependencies found may arise from different levels of processing, with intramodal response-stimulus contrast arising from sensory differentiation, inter- and intramodality response-response assimilation from perceptual categorization processes, and intermodality response-stimulus contrast from cognitive expectancies.     

Anchoring and relational judgments by young children and retardates

In five experiments using as dimensions brightness, texture, facial happiness, height, and weight, young children (ages 3.4 to 5.3 years) rendered bipolar judgments of stimuli intermediate in value between alternately given extreme anchors. Consistent relational shifts away from the anchors were found for all dimensions judged, and these effects proved virtually independent of children’s ages, the sequential orders of stimulus and anchor presentation, or the provision of overt visual memory props. Evidence of relational judgment within the narrower range of the test stimuli alone was also found. Essentially similar relational judgments were replicated with a sample of severe adult mental retardates.     

Absolute identification by relative judgment

In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative relative judgment model (RJM) in which the elemental perceptual units are representations of the differences between current and previous stimuli. These differences are used, together with the previous feedback, to respond. Without using long-term representations of absolute magnitudes, the RJM accounts for (a) information transmission limits, (b) bowed serial position effects, and (c) sequential effects, where responses are biased toward immediately preceding stimuli but away from more distant stimuli (assimilation and contrast).     

Holistic vs. attribute repetition effects in classifying stimuli

The effect of the just previous stimulus on the current response was determined in three speeded classification experiments. When the stimuli were perceptual patterns, and when they were words, there was marked facilitation if the previous stimulus was identical to the current stimulus. When successive perceptual stimuli were composed of identical elements, but in a changed configuration, there was no measureable sequential effect on “same” response times. These results are for integral stimuli. When stimuli are not integral, as with some studies in the literature, it is suggested that each two-dimensional nonintegral stimulus is treated by the observer as two objects. In those cases, responses can be facilitated by repetition of that object on which responses were based on the previous trial, and this can occur when a value of the other dimensions (other objects) has not repeated. Accordingly, the processing of integral and nonintegral stimuli must be considered separately when attempting to evaluate process models. Further, facilitation due to stimulus repetitions does not account for all of the differences in response times between various classification tasks. These additional differences may be attributed to a multidimensional range effect analogous to the range effects found in psychophysical tasks.     

The role of crossmodal competition and dimensional overlap in crossmodal attention switching

Crossmodal selective attention was investigated in a cued task switching paradigm using bimodal visual and auditory stimulation. A cue indicated the imperative modality. Three levels of spatial S–R associations were established following perceptual (location), structural (numerical), and conceptual (verbal) set-level compatibility. In Experiment 1, participants switched attention between the auditory and visual modality either with a spatial-location or spatial-numerical stimulus set. In the spatial-location set, participants performed a localization judgment on left vs. right presented stimuli, whereas the spatial-numerical set required a magnitude judgment about a visually or auditorily presented number word. Single-modality blocks with unimodal stimuli were included as a control condition. In Experiment 2, the spatial-numerical stimulus set was replaced by a spatial-verbal stimulus set using direction words (e.g., “left”). RT data showed modality switch costs, which were asymmetric across modalities in the spatial-numerical and spatial-verbal stimulus set (i.e., larger for auditory than for visual stimuli), and congruency effects, which were asymmetric primarily in the spatial-location stimulus set (i.e., larger for auditory than for visual stimuli). This pattern of effects suggests task-dependent visual dominance.     

Short-term memory for event duration: Modality specificity and goal dependency

Time perception is involved in various cognitive functions. This study investigated the characteristics of short-term memory for event duration by examining how the length of the retention period affects inter- and intramodal duration judgment. On each trial, a sample stimulus was followed by a comparison stimulus, after a variable delay period (0.5?C5?s). The sample and comparison stimuli were presented in the visual or auditory modality. The participants determined whether the comparison stimulus was longer or shorter than the sample stimulus. The distortion pattern of subjective duration during the delay period depended on the sensory modality of the comparison stimulus but was not affected by that of the sample stimulus. When the comparison stimulus was visually presented, the retained duration of the sample stimulus was shortened as the delay period increased. Contrarily, when the comparison stimulus was presented in the auditory modality, the delay period had little to no effect on the retained duration. Furthermore, whenever the participants did not know the sensory modality of the comparison stimulus beforehand, the effect of the delay period disappeared. These results suggest that the memory process for event duration is specific to sensory modality and that its performance is determined depending on the sensory modality in which the retained duration will be used subsequently.     

Bimanual response grouping in dual-task paradigms

In three experiments we measured response time (RT) and peak force (PF) to investigate the grouping of left- and right-hand key press responses in a dual-task paradigm involving two independent go/no-go tasks. Within each task, a go stimulus within one of two modalities (i.e., visual versus auditory) required a response by one hand. In Experiment 1 with simultaneous go stimuli in the two tasks, responses appeared to be grouped in approximately 75-80% of trials, compared with nearly 100% grouping in a single-task condition requiring bimanual responses to the onset of any stimulus in either modality. In Experiment 2 with stimulus onset asynchronies (SOAs) of 0-400 ms between the two go stimuli, response grouping clearly declined as SOA increased, although some grouping was still evident even at the longest SOA. The same pattern was observed in Experiment 3 with the same range of SOAs but unpredictable stimulus order, suggesting that grouping is not strongly dependent on prior knowledge of the likely response order. These results emphasize the pervasiveness of response grouping in bimanual dual-task RT paradigms and provide useful clues as to its nature.     

Crossmodal attention switching: Auditory dominance in temporal discrimination tasks

Visual stimuli are often processed more efficiently than accompanying stimuli in another modality. In line with this “visual dominance”, earlier studies on attentional switching showed a clear benefit for visual stimuli in a bimodal visual–auditory modality-switch paradigm that required spatial stimulus localization in the relevant modality. The present study aimed to examine the generality of this visual dominance effect. The modality appropriateness hypothesis proposes that stimuli in different modalities are differentially effectively processed depending on the task dimension, so that processing of visual stimuli is favored in the dimension of space, whereas processing auditory stimuli is favored in the dimension of time. In the present study, we examined this proposition by using a temporal duration judgment in a bimodal visual–auditory switching paradigm. Two experiments demonstrated that crossmodal interference (i.e., temporal stimulus congruence) was larger for visual stimuli than for auditory stimuli, suggesting auditory dominance when performing temporal judgment tasks. However, attention switch costs were larger for the auditory modality than for visual modality, indicating a dissociation of the mechanisms underlying crossmodal competition in stimulus processing and modality-specific biasing of attentional set.     

Selective attention to the chemosensory modality

Previous studies have shown that behavioral responses to auditory, visual, and tactile stimuli are modulated by expectancies regarding the likely modality of an upcoming stimulus (see Spence & Driver, 1997). In the present study, we investigated whether people can also selectively attend to the chemosensory modality (involving responses to olfactory, chemical, and painful stimuli). Participants made speeded spatial discrimination responses (left vs. right) to an unpredictable sequence of odor and tactile targets. Odor stimuli were presented to either the left or the right nostril, embedded in a birhinally applied constant airstream. Tactile stimuli were presented to the left or the right hand. On each trial, a symbolic visual cue predicted the likely modality for the upcoming target (the cue was a valid predictor of the target modality on the majority of trials). Response latencies were faster when targets were presented in the expected modality than when they were presented in the unexpected modality, showing for the first time that behavioral responses to chemosensory stimuli can be modulated by selective attention.     

Reinforcement of spaced responding in a simultaneous discrimination

Pigeons were exposed to three stimuli simultaneously with responses reinforced according to differential-reinforcement-of-low-rate schedules. Responses to one stimulus (the positive stimulus) that were spaced appropriately resulted in food presentation. The variables manipulated were the time parameter of the schedule (5, 10, 20, 30 sec) and the consequences of responding to the other two stimuli (the negative stimuli). The percentage of the total responses that occurred to each stimulus was independent of the schedule value but was dependent on the consequences of responding to the negative stimuli. If responses to both reset the schedule timer, responding was confined largely to the positive stimulus. If responses to neither had scheduled effects, the birds were more likely to respond to those stimuli. Responding to one negative stimulus could be selectively attenuated by having responses to that stimulus alone reset the timer. With the schedule time value held constant, the absolute rate of responding to the positive stimulus was either stable or decreased with maintained exposure; it did not change as a function of increases or decreases in responding to the negative stimuli. Rather than interacting and affecting each other, responses to the three stimuli were controlled independently by their relation to reinforcement. There was no evidence that responses to the negative stimuli mediated the spacing of responses to the positive stimulus.