Similarity, confusability, and the density hypothesis.

Results from several letter- and digit-identification studies have been interpreted (Appelman & Mayzner, 1982; Krumhansl, 1982) as providing support for the hypothesis that psychological similarity is influenced by the local density of items in the stimulus space. This conclusion is questioned on the grounds that density was not directly manipulated in the studies, thus alternative explanations based on other stimulus characteristics cannot be excluded. In the present article six experiments are reported in which stimulus density was manipulated. In three experiments using similarity ratings and two using discrimination confusions, no effect of stimulus density was found. However, the identification counterpart of one of the discrimination studies did provide evidence of an effect of density on response probabilities. It is concluded that stimulus density can affect identification performance through its influence on the choice process implicit in any identification task, but is not an important determinant of psychological similarity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two verbal aspects of language and thought in schizophrenia.

Replicated an experiment by A. Burstein (see PA, Vol. 36:3JQ55B) on the incorrect word choices of schizophrenics, with more rigorous control of the intelligence variable. It was hypothesized that 60 schizophrenics would exceed 50 normals of similar intelligence (as measured by the Shipley-Institute of Living Scale for Measuring Intellectual Impairment Vocabulary test) in choosing homonyms and antonyms when instructed to select synonyms for stimulus words. Results support the hypothesis, indicating that schizophrenics confuse cognitive criteria for determining similarity of word meaning with word sound and opposition of word meaning, regardless of intelligence level. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Psychophysical judgment: electro-cortical and heart rate correlates of accuracy and uncertainty

The relationship between perceptual accuracy and physiological response amplitude was investigated in an auditory pitch discrimination experiment. Confidence ratings were obtained from all subjects following each trial. The stimulus set consisted of three tones of different frequencies spaced in a manner to provide both easy and difficult discriminations. Heart rate, EEG and vertical eye movement were recorded throughout the experiment. The results of the experiment indicated that the largest evoked cardiac rate response was elicited by the stimulus which produced the fewest errors in judgment; larger auditory evoked potentials, particularly the late positive component (P300), were associated with the 'easy' stimulus; greater cortical negativity was associated with the difficult stimuli. Eye activity was found to covary with judgmental accuracy; cortical slow wave activity was particularly sensitive to the confidence, or 'uncertainty' parameter. A 'decision tree' model was hypothesized to describe the processing mechanism involved in solving the discrimination problem.     

Testing response generation rules: A reply to Miller, Schachtman, and Matzel (1988).

In a series of autoshaping studies, Robbins (1988) demonstrated that performance after random presentations of a conditioned stimulus and unconditioned stimulus is not altered by later changes in the value of the training context. These results appear inconsistent with predictions made by the comparator hypothesis of conditioned performance advanced by Miller and Schachtman (1985a). Miller, Schachtman, and Matzel (1988) argue, however, that Robbins's procedures did not provide an appropriate test of the comparator model. They further claim that abundant evidence currently exists to support other predictions of the comparator hypothesis. I argue here that my procedures were particularly well suited to testing unique predictions of the model. Moreover, my results add to body of literature which suggests that the generality of the comparator mechanism as a determinant of performance may be severely limited. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Political orientation and the perceptual effects of an anticipated interaction.

"… to shed further light on the conditions favoring similarity and complementarity in social preference, an experiment was designed to investigate the perception of a political stimulus person… by Ss varying in the strength of their own political orientation… . measured… by… political [scales]… . Ss were led to anticipate interacting with one of the stimulus persons, while in a control condition… there would be no expectation of ever meeting the SP." The results indicated that, "people with a strong need to manipulate their social enviornment tend to devalue others with similar orientation when a competetive interaction is anticipated." 15 refs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of hippocampal lesions in overshadowing and blocking procedures.

The effects of ibotenic acid lesions of the hippocampus on overshadowing and blocking were examined in a Pavlovian appetitive conditioning experiment with rats. In a standard test of performance to the overshadowed or blocked target stimulus, sham-lesioned rats displayed both of these stimulus-selection phenomena. Rats with hippocampal lesions showed normal blocking, but no overshadowing. Subsequent inhibitory learning about the target stimulus was slower after overshadowing or blocking procedures than after a control procedure in sham-lesioned rats, but not in lesioned rats. These results suggest that exposure to these procedures can induce hippocampally mediated losses in conditioned stimulus associability (learning rate parameter), even when those losses are not a major determinant of the stimulus-selection effects themselves. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Testing the density hypothesis: Comment on Corter.

Corter (1987) reported a series of six experiments examining three measures of psychological proximity (similarity judgments, discrimination confusions, and identification errors) for effects of adding context stimuli similar to one of the target elements. The density hypothesis (Krumhansl, 1978) and the diagnosticity principle (Tversky, 1977) both predict that the added context elements should decrease the proximity of elements similar to the added context elements relative to elements dissimilar from the added context elements. This comment discusses various theoretical and practical considerations in assessing context effects on psychological proximity. A reanalysis of the data of Corter's first experiment shows a relatively large effect of the density manipulation consistent with predictions. That the remaining experiments do not show the predicted effect may be attributed to the small number of stimuli and limited control over the similarity structure of the stimulus sets. Difficulties are noted in interpreting density effects in identification data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age-related functional field losses are not eccentricity dependent

Previous studies have found an increase in peripheral target localization errors in normally sighted older adults. These results have been interpreted as indicative of a constriction of the "useful field of view". In the present study, we parametrically manipulated masking, distractors and stimulus luminance and examined the relationships between peripheral target localization and age. We found that backward masking and/or flashed distractors increased error rates. This decrement in performance was larger for more peripherally located targets and largest for the older subjects at all stimulus locations. Stimulus luminance (either 2 or 78 cd/m2) had no effect on peripheral localization performance at any age. We also demonstrated that all subjects, regardless of age, had higher localization error rates to more peripherally located targets. In older subjects, error rates increased equally at all eccentricities; that is, there was an eccentricity independent increase in the number of target localization errors as a function of age. This finding does not support the interpretation of a selective constriction of the functional visual field in older subjects.     

Effects of stimulus complexity on mental rotation rate of polygons.

Both spatial and propositional theories of imagery predict that the rate at which mental images can be rotated is slower the more complex the stimulus. Four experiments (three published and one unpublished) testing that hypothesis found no effect of complexity on rotation rate. It is argued that despite continued methodological improvements, subjects in the conditions of greater complexity may have found it sufficient to rotate only partial images, thereby vitiating the prediction. The two experiments reported here are based on the idea of making the discriminative response sufficiently difficult so as to force the rotation of complete images. The first one scaled the similarity between standard polygons and certain systematically mutated versions. From the ratings so obtained, two levels of perceived similarity, high and low, were defined and served as separate conditions in a response-time, image rotation experiment. The second experiment tested the complexity hypothesis by examining the effect of similarity on rotation rates and its interaction with levels of complexity. The results support the complexity hypothesis, but only for the highly similar stimuli. Rotation times were also generally slower for high as compared with low similarity. It is argued that these results arise because subjects rotate incomplete images when the stimuli are not very similar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Timing and reaction time.

Because reaction time (RT) tasks are generally repetitive and temporally regular, participants may use timing strategies that affect response speed and accuracy. This hypothesis was tested in 3 serial choice RT experiments in which participants were presented with stimuli that sometimes arrived earlier or later than normal. RTs increased and errors decreased when stimuli came earlier than normal, and RTs decreased and errors increased when stimuli came later than normal. The results were consistent with an elaboration of R. Ratcliff's diffusion model (R. Ratcliff, 1978; R. Ratcliff & J. N. Rouder, 1998; R. Ratcliff, T. Van Zandt, & G. McKoon, 1999), supplemented by a hypothesis developed by D. Laming (1979a, l979b), according to which participants initiate stimulus sampling before the onset of the stimulus at a time governed by an internal timekeeper. The success of this model suggests that timing is used in the service of decision making. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An experimental reunion of psychoanalytic theory with perceptual vigilance and defense.

"This experiment was designed to test, within the framework of perceptual behavior, two psychoanalytic hypotheses: (a) the unconscious striving for expression of underlying psychosexual impulses (vigilance); and (b) the warding off of these threatening impulses as they begin to approach conscious awareness (defense)." Using Blacky Pictures, the vigilance hypothesis was supported in 11 of the 14 cases tested; the defense hypothesis was supported in 12 of the 14 cases tested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reading ability and semantic processing: Isolating speed of access.

Although much attention has focused on the efficiency of access to semantic information as a determinant of reading ability, previous research has confounded information access and decision processes. The authors used a matching task to study the time course of semantic access among college students. They studied the time course of processing by varying the stimulus onset between the two members of a stimulus pair. Semantic encoding functions obtained from this paradigm were used to isolate semantic access from the decision component of the matching task. Regression analyses indicated that the often-obtained correlation between speed of semantic processing and measures of reading ability is based on unique contributions from both semantic access and decision processes. The results undermine the hypothesis that the efficiency of access to semantic codes is a relatively age-variant contributor to individual differences in reading. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relationship between real similarity and assumed similarity with favorability controlled.

"The present study tests the hypothesis that subjects who share a number of characteristics in common with a stimulus person tend to assume greater similarity to him in common with him. Special attention is given to controlling the influence of favorability on the measurements of assumed similarity… . The data almost completely fail to support the hypothesis that… [assumed similarity] varies with… [real similarity] when the favorability component is controlled… . the data suggest that, when the stimulus object is relatively socially acceptable and has characteristics with which all S's are relatively familiar… [assumed similarity] is determined primarily by the favorability response set… and is almost uninfluenced by… [real similarity]." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Spontaneous Recovery From Forward and Backward Blocking.

This article demonstrates and analyzes spontaneous recovery of stimulus control following both forward and backward blocking in a conditioned suppression preparation with rats. Experiment 1 found, in first-order conditioning, robust forward blocking and an attenuation of it following a retention interval. Experiment 2 showed, in sensory preconditioning, recovery of responding following both forward and backward blocking. Also, the results of this experiment indicated that response recovery to the blocked stimulus cannot be explained by an impaired status of the blocking stimulus after a retention interval. Experiment 3, also in sensory preconditioning, suggested that spontaneous recovery following both forward and backward blocking in Experiment 2 was due to impaired associative activation of the blocking stimulus' representation during testing with the blocked stimulus. Although no contemporary model of associative learning can explain these results, a modification of R. R. Miller and L. D. Matzel's (1988) comparator hypothesis is proposed to do so. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organizational factors in selective attention: The interplay of acoustic distinctiveness and auditory streaming in the irrelevant sound effect.

A series of studies further explored the way in which irrelevant sound disrupts the serial recall of visually presented verbal sequences. The hypothesis that distinctiveness (stimulus mismatch) within auditory irrelevant sequences is a critical determinant of disruption of serial recall was tested. Experiment 1 showed that the degree of disruption was related to the degree of mismatch between successive stimuli. However, in Experiment 2, changes in 2 attributes of a stimulus produced less disruption than when only 1 was changed, suggesting mismatch alone was not the key factor. These results were reconciled with the changing-state hypothesis in Experiment 3 in which change and disruption were monotonically related up to the point at which mismatch created 2 streams. Object-based theories are able to explain this pattern of results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Amount of verbal information and ear-differences in 5- and 6-year old boys and girls

Tow experiments were performed. The first was to determine the effects of varying the amount of information in verbal instructions presented monaurally on differences between ears and sex in 5-yr.-old boys and girls. Verbal instructions were given for the performance of a visual-motor task. The results indicated that the amount of verbal information affects ear-asymmetry in girls and not boys. The second experiment was performed to determine the effects of varying the amount of verbal information in verbal instructions presented monaurally on differences between ears, sexes, and reading ability of 6-yr.-old boys and girls. The findings indicated that above average readers performed better than below average readers. Ear-asymmetry was observed across sex and reading abilities for sentences containing 7 and 8 stimulus attributes. No ear-asymmetry was observed in sentences containg 9 stimulus attributes. The results appear to support the progressive lateralization hypothesis which states that ear-asymmetry is dependent on task conditions. The results also support sex differences in the development of brain lateralization.     

Dishabituation of the electrodermal orienting response following decay of sensitization

This study tested one of the basic propositions of dual-process theory (Groves and Thompson, 1970) that 'dishabituation' results from an independent, superimposed process of excitation and not from disruption of the habituation process as proposed by Sokolov (1963). Skin conductance level (SCL) was employed as a measure of sensitization. On the basis of dual-process theory, it was hypothesized that if sensitization produced by the 'dishabituating' stimulus has decayed prior to re-presentation of the habituating stimulus, skin conductance response (SCR) amplitude to the habituating stimulus will not differ from that displayed by a control group which did not receive presentation of the 'dishabituating' stimulus. In experiment 1 (N = 10), subjects received 13 presentations of a 1000 Hz, 70 dB tone of 3 sec duration with interstimulus intervals of 40, 50 and 60 sec. Between trials 11 and 12, there was one presentation of a dishabituating (light) stimulus. Analysis of SCL indicated that an interval of 50 sec between trials 12 and 13 was sufficient to allow sensitization to decline to the pre-light level. The experimental conditions in experiment 2 (N = 32) were the same as in experiment 1 except that only half the subjects received presentation of the dishabituating stimulus. The results indicated that although there were no group differences in SCR amplitude on trials 1-11, experimental subjects displayed significantly larger responses on trial 13 than did control subjects. These results suggest that interpolation of a different stimulus in an habituation series does, in fact, disrupt the habituation process.     

Are selective adaptation and contrast effects really distinct?

Although there is evidence that selective adaptation and contrast effects in speech perception are produced by the same mechanisms, J. R. Sawusch and P. Jusczyk (see record 1982-00351-001) reported a dissociation between the effects and concluded that adaptation and contrast occur at separate processing levels. They found that an ambiguous test stimulus was more likely to be labeled b following adaptation with [pha] and more likely to be labeled p following adaptation with [ba] or [spa], the latter consisting of [ba] preceded by [s] noise. In the contrast session, where a single context stimulus occurred with a single test item, the [ba] and [pha] contexts had contrastive effects similar to those of the [ba] and [pha] adaptors, but the [spa] context produced an increase in b responses to the test stimulus, an effect opposite to that of the [spa] adaptor. One interpretation of this difference is that the rapid presentation of the [spa] adaptor gave rise to streaming, whereby the [s] was perceptually segregated from the [ba]. The present experiment, with 37 undergraduates, essentially replicated the results of Sawusch and Jusczyk, using procedures similar to theirs. An increase in the interadaptor interval to remove the likelihood of stream segregation produced a convergence between the adaptation and contrast effects. It is concluded that the relationship between the feature-detection hypothesis and adaptation results remains highly equivocal. (46 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Common and distinctive features of verbal and pictorial stimuli as determinants of psychophysiological responsivity.

The present study focuses on the relation between stimulus features and psychophysiological responsivity by using a modified version of the information detection paradigm. Compound pictorial and verbal stimuli were used as the relevant stimuli that Ss were instructed to memorize. Skin conductance responses were measured during the subsequent presentation of a sequence of test stimuli. We hypothesized that the electrodermal responsivity to the critical stimulus would reflect the degree it matches the relevant one. The results indicated that when the critical stimulus was identical to the relevant stimulus, responsivity was maximal. Neutral stimuli produced minimal responsivity, and critical stimuli that only partially matched the relevant one produced intermediate levels of responsivity (in spite of the subjects' awareness of the differences between the critical and the relevant stimuli). Comparison of the geometric and contrast models for similarity showed that the pattern of responsivity violated the minimality and symmetry assumptions of the geometric model. The relation between cognitive processes and psychophysiological responsivity is discussed, as are implications for the application of the guilty knowledge technique for detecting information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Attitude and activity preference similarity: Differential bases of interpersonal attraction for low and high self-monitors.

The paradigmatic research of Byrne (1971) on the similarity–attraction relation has been recently challenged by the view that it is the similarity of people's pastime preferences more than the similarity of their attitudes that may better predict both friendship and initial attraction (Werner & Parmelee, 1979). An integration of these two views is proposed in the hypothesis that the personality variable of self-monitoring (Snyder, 1974) may moderate both the attitude similarity–attraction relation and the activity preference similarity–attraction relation in initial interpersonal attraction. An experiment is reported in which low and high self-monitors formed impressions of four same-gender persons representing each of the crossed combinations of high and low value-based attitude similarity, and high and low activity preference similarity. As predicted, for low self-monitors, attitude similarity influenced initial attraction to the stimulus persons more than did activity perference similarity, and this was expressed most strongly on attraction ratings relevent to the attitude domain (i.e., judgments of respect and inferences of intellectually desirable personality traits). By contrast, for high self-monitors, activity preference similarity influenced initial attraction more than did attitude similarity, and this was expressed most strongly on attraction ratings relevant to the activity preference domain (i.e., judgments of liking and inferences of socially desirable personality traits). (PsycINFO Database Record (c) 2010 APA, all rights reserved)