Extraversion and neuroticism in orienting reflex dishabituation

The present study examined the effects of extraversion (E) and neuroticism (N) as individual difference dimensions and of stimulus intensity on electrodermal orienting response habituation, test response, and dishabituation. Subjects were 162 college students selected from a screening sample of 860 as representing extreme groups of high, medium, and low E crossing with high, medium, and low N. Subjects in all nine resulting groups were habituated to criterion on auditory stimuli of 60, 80, and 100 db. A novel (test) stimulus and a dishabituating standard stimulus followed criteron habituation at each intensity. Results indicated that response amplitude for initial, test, and dishabituation responses was a direct function and that habituation rate (trials-to-criterion) was an inverse function of stimulus intensity. Extraverts habituated more rapidly than introverts at high intensity and gave smaller test and dishabituation responses. Some results differed when regression coefficients defined habituation rate and when first stimulus intensities alone were examined. Correlations among initial, test, and dishabituation responses and between each of these and the two measures of habituation rate are also reported. Results were interpreted as partially supportive of Eysenck's theory.     

Pitch and pitch change interact in auditory displays

Designing auditory displays requires understanding how different attributes of sound are processed. Operators must often listen to a particular stimulus dimension and make control actions contingent on the auditory information. Three experiments used a selective-listening paradigm to examine interactions between auditory dimensions. Participants were instructed to attend to either relative pitch or direction of pitch change of dynamic stimuli. With vertically arranged keypress responses, reactions to both dimensions showed stimulus-response compatibility effects, indicating that pitch is treated spatially. Direction of pitch change affected responses to pitch; level of pitch more strongly affected responses to pitch change. To reduce deleterious effects of irrelevant pitch information, auditory display designers can restrict the pitch range used to display dynamic data.     

Spontaneous number discrimination of multi-format auditory stimuli in cotton-top tamarins (Saguinus oedipus)

Studies using operant training have demonstrated that laboratory animals can discriminate the number of objects or events based on either auditory or visual stimuli, as well as the integration of both auditory and visual modalities. To date, studies of spontaneous number discrimination in untrained animals have been restricted to the visual modality, leaving open the question of whether such capacities generalize to other modalities such as audition. To explore the capacity to spontaneously discriminate number based on auditory stimuli, and to assess the abstractness of the representation underlying this capacity, a habituation-discrimination procedure involving speech and pure tones was used with a colony of cotton-top tamarins. In the habituation phase, we presented subjects with either two- or three-speech syllable sequences that varied with respect to overall duration, inter-syllable duration, and pitch. In the test phase, we presented subjects with a counterbalanced order of either two- or three-tone sequences that also varied with respect to overall duration, inter-syllable duration, and pitch. The proportion of looking responses to test stimuli differing in number was significantly greater than to test stimuli consisting of the same number. Combined with earlier work, these results show that at least one non-human primate species can spontaneously discriminate number in both the visual and auditory domain, indicating that this capacity is not tied to a particular modality, and within a modality, can accommodate differences in format.     

Effects of multimodal presentation and stimulus familiarity on auditory and visual processing

Two experiments examined the effects of multimodal presentation and stimulus familiarity on auditory and visual processing. In Experiment 1, 10-month-olds were habituated to either an auditory stimulus, a visual stimulus, or an auditory-visual multimodal stimulus. Processing time was assessed during the habituation phase, and discrimination of auditory and visual stimuli was assessed during a subsequent testing phase. In Experiment 2, the familiarity of the auditory or visual stimulus was systematically manipulated by prefamiliarizing infants to either the auditory or visual stimulus prior to the experiment proper. With the exception of the prefamiliarized auditory condition in Experiment 2, infants in the multimodal conditions failed to increase looking when the visual component changed at test. This finding is noteworthy given that infants discriminated the same visual stimuli when presented unimodally, and there was no evidence that multimodal presentation attenuated auditory processing. Possible factors underlying these effects are discussed.     

Habituation and the human evoked potential

Habituation of human scalp-recorded cerebral evoked potentials was studied in response to auditory and visual repetitive stimuli of different intensities. Changes in magnitudes of evoked potentials with stimulus repetition were examined according to the parametric characteristics of habituation, generalization, and dishabituation. In addition, tests of the predictions of two theories of habituation were made regarding the degree and direction of intensity generalization of habituation. Both auditory and visual evoked potentials exhibited decrements in response magnitudes across the repetitive stimuli consistent with the parametric criteria of habituation. Early evoked potential peak components showed a pattern of intensity generalization of habituation consistent with the predictions of the dual-process theory of habituation. Intensity generalization of late evoked potential peak components occurred in a manner more consistent with the predictions of the stimulus comparator theory of habituation. These results provide further evidence that evoked potentials can be used as electrophysiological indexes of plasticity in humans.     

Transfer of noncorresponding spatial associations to the auditory Simon task

Four experiments examined transfer of noncorresponding spatial stimulus-response associations to an auditory Simon task for which stimulus location was irrelevant. Experiment 1 established that, for a horizontal auditory Simon task, transfer of spatial associations occurs after 300 trials of practice with an incompatible mapping of auditory stimuli to keypress responses. Experiments 2-4 examined transfer effects within the auditory modality when the stimuli and responses were varied along vertical and horizontal dimensions. Transfer occurred when the stimuli and responses were arrayed along the same dimension in practice and transfer but not when they were arrayed along orthogonal dimensions. These findings indicate that prior task-defined associations have less influence on the auditory Simon effect than on the visual Simon effect, possibly because of the stronger tendency for an auditory stimulus to activate its corresponding response.     

Autoshaping in the rat: The effects of localizable visual and auditory signals for food

Two experiments investigated autoshaping in rats to localizable visual and auditory conditioned stimuli predicting response-independent food. In Experiment 1 considerable conditioned-stimulus approach behavior was generated by a localizable visual conditioned stimulus that was situated approximately 35 cm from the food tray. Using the same apparatus in Experiment 2 we found that the conditioned-stimulus approach was generated only to a visual conditioned stimulus and not to a localizable auditory conditioned stimulus even though subjects (1) could discriminate presentations of the auditory conditioned stimulus, (2) had associated it with food, (3) could localize it, and (4) would approach the auditory stimulus if this behavior constituted an instrumental response to food. The predominant conditioned responses to the auditory stimuli were goal tracking (entering the food tray) and orienting towards the food-paired conditioned stimulus by head turning and rearing and turning. These results imply that rats do not invariably approach a localizable appetitive Pavlovian conditioned stimulus but that stimulus-approach responses depend on the nature and modality of the conditioned stimulus.     

Are crossmodal correspondences relative or absolute? Sequential effects on speeded classification

Crossmodal correspondences have often been demonstrated using congruency effects between pairs of stimuli in different sensory modalities that vary along separate dimensions. To date, however, it is still unclear the extent to which these correspondences are relative versus absolute in nature: that is, whether they result from pre-defined values that rigidly link the two dimensions or rather result from flexible values related to the previous occurrence of the crossmodal stimuli. Here, we investigated this issue in a speeded classification task featuring the correspondence between auditory pitch and visual size (e.g., congruent correspondence between high pitch/small disc and low pitch/large disc). Participants classified the size of the visual stimuli (large vs. small) while hearing concurrent high- or low-pitched task-irrelevant sounds. On some trials, visual stimuli were paired instead with “intermediate” pitch, that could be interpreted differently according to the auditory stimulus on the preceding trial (i.e., as “lower” following the presentation of a high pitch tone, but as “higher” following the presentation of a low pitch tone). Performance on sequence-congruent trials (e.g., when a small disc paired with the intermediate-pitched tone was preceded by a low pitch tone) was compared to sequence-incongruent trials (e.g., when a small disc paired with the intermediate-pitch tone was by a high-pitched tone). The results revealed faster classification responses on sequence-congruent than on sequence-incongruent trials. This demonstrates that the effect of the pitch/size correspondence is relative in nature, and subjected to trial-by-trial interpretation of the stimulus pair.     

Form categorization in 10-month-olds

In five experiments, 10-month-olds were habituated to exemplars of a form category and tested for categorization in paired-comparison trials involving in-category versus out-of-category stimuli. Across these experiments, color was systematically manipulated during habituation and/or test trials. Infants categorized form when color was either held constant or varied during habituation, but failed to categorize form when exposed to color-constant stimuli during habituation and tested for categorization with novel-color form exemplars. Two subsequent experiments traced this failure to the narrow experience of exposure to color-constant exemplars during habituation. These results suggest that (a) infants' internal representation for a category will not include a stimulus dimension not varied in the exemplars from which the category was derived, but (b) if variation in that dimension is experienced, exemplars constructed of novel instances of that dimension will still be regarded as belonging to the category.     

Newborns discriminate schematic faces from scrambled faces.

Newborn attention to, and discrimination of, facelike patterns was examined in three experiments employing 35 one- to three-day-old infants. Differential eye tracking and head turning to three moving stimuli (a schematic face, a scrambled face, and a luminance-matched blank) were measured in two of the three experiments. The newborns turned their eyes and heads farther to follow patterned stimuli, containing facelike features, than to a luminance-matched blank, but they did not turn farther to a stimulus with the features arranged in a facelike manner compared to features scrambled. A third experiment tested newborns' ability to discriminate between the facelike and scrambled face patterns. Using an infant-controlled procedure, infants showed similar initial fixation times and similar numbers of trials to reach a 60% response decrement criterion to both patterned stimuli. Following habituation, novelty responding indicated that infants discriminated between the schematic face and the scrambled face patterns. Although infants did not show a preference for a facelike stimulus compared to a features-scrambled pattern in the present experiments, they could discriminate the two patterns based on the internal arrangement of the facial features.     

Influence of auditory and audiovisual stimuli on the right–left prevalence effect

When auditory stimuli are used in two-dimensional spatial compatibility tasks, where the stimulus and response configurations vary along the horizontal and vertical dimensions simultaneously, a right–left prevalence effect occurs in which horizontal compatibility dominates over vertical compatibility. The right–left prevalence effects obtained with auditory stimuli are typically larger than that obtained with visual stimuli even though less attention should be demanded from the horizontal dimension in auditory processing. In the present study, we examined whether auditory or visual dominance occurs when the two-dimensional stimuli are audiovisual, as well as whether there will be cross-modal facilitation of response selection for the horizontal and vertical dimensions. We also examined whether there is an additional benefit of adding a pitch dimension to the auditory stimulus to facilitate vertical coding through use of the spatial-musical association of response codes (SMARC) effect, where pitch is coded in terms of height in space. In Experiment 1, we found a larger right–left prevalence effect for unimodal auditory than visual stimuli. Neutral, non-pitch coded, audiovisual stimuli did not result in cross-modal facilitation, but did show evidence of visual dominance. The right–left prevalence effect was eliminated in the presence of SMARC audiovisual stimuli, but the effect influenced horizontal rather than vertical coding. Experiment 2 showed that the influence of the pitch dimension was not in terms of influencing response selection on a trial-to-trial basis, but in terms of altering the salience of the task environment. Taken together, these findings indicate that in the absence of salient vertical cues, auditory and audiovisual stimuli tend to be coded along the horizontal dimension and vision tends to dominate audition in this two-dimensional spatial stimulus–response task.     

Pitch as a phonemic cue

Three experiments that were designed to determine how pitch information is represented in auditory memory are reported. A same-different reaction time was used in all three experiments. Previous experiments have interpreted the finding of faster “same” responses to acoustically identical pairs than to pairs that are phonemically identical but acoustically distinct as indicating that there is a memory that preserves auditory information. It has been assumed that this can be used to match “same” pairs only if the formant frequencies of the members of the pair are the same. In the first experiment, the size of this matching advantage for pairs with identical formant frequencies was not altered when the members of the pair were on different pitches. This indicates that pitch is represented separately from the formants at the auditory level. The second and third experiments used a bigger pitch difference when the pairs were on a different pitch, which, for one of the stimulus sets, resulted in a change in vowel quality but not in the identity of the consonant. In the other stimulus set, both phonemes of the syllable remained the same when presented on different pitches. The matching advantage was reduced when the stimuli were on different pitches for both stimulus sets. This indicates that a difference in pitch can prevent matching at the auditory level under some circumstances. An additional finding, a reduced residual matching advantage when the syllable changes, indicates that at least a syllable-length representation is held in auditory memory. The results are discussed with respect to how the representation in auditory memory might be used in the perception of speech produced by different speakers.     

Habituation and dishabituation of the electrodermal orienting reflex in relation to extraversion and neuroticism

Orienting reflex (OR) habituation and dishabituation may be influenced by individual difference variables, including Eysenck's Extraversion (E) and Neuroticism (N) dimensions. Ninety subjects formed nine groups based on the crossover of high, medium, and low E and N. Each subject received, at each of two auditory stimulus intensities, two blocks of tone presentations. The last standard stimulus trial was followed by a novel stimulus and four repetitions of the standard stimulus. Using square root SCR, extraverts showed smaller initial response amplitudes than introverts at the low intensity of stimulation, while the reverse was true at high intensity. E and N were unrelated to SCR habituation rate. However, extraverts showed no dishabituation, while introverts did dishabituate.     

Effects of stimulus duration and intensity on the rate and specificity of behavioural habituation

Tone stimuli were presented to rats once per day until habituation was reached. Neither the duration nor the intensity of the stimulus affected the rate of habituation. Habituation was specific to both these stimulus parameters as shown by the distraction produced by either an increase or a decrease in the original stimulus value. It is suggested that some of the discrepancies in the literature might be resolved if a distinction is drawn between habituation of orienting responses and the decrement of more specific responses.     

Optional processes in similarity judgments

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configurai dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identifled-beforernandatory processes can be understood.     

Optional processes in similarity judgments.

This research investigates the nature of similarity relations among three pairs of interacting dimensions: (1) the integral dimensions of auditory pitch and loudness, (2) the configural dimensions of paired parentheses, and (3) the cross-modally corresponding dimensions of visual position and auditory pitch. We evaluated the rules by which information from each dimension combines in similarity judgments. Our claim is that, when judging similarity, processes that are obligatory, or what we call mandatory processes, can commingle with processes of choice, or what we call optional processes. By varying instructions, we found strong evidence of optional processing. Instructions to rate overall similarity encouraged subjects to attend to stimuli as wholes and led to a Euclidean rule in similarity scaling. Instructions to focus on dimensions encouraged subjects to consider each stimulus dimension separately and led to a city-block rule. We argue that optional processes may obscure mandatory ones, and so need to be identified before mandatory processes can be understood.     

S.I.M.P.L.E. control and measurement of auditory events

A SIMPLE interactive programming language is shown to be useful for psychological research involving auditory stimuli and responses. It is helpful in recording spoken stimulus tapes with program control of event sequencing and timing; it can control on-line interactive auditory and bisensory experiments; and it can calibrate the stimulus durations and pause times for auditory events.     

Sex differences in fetal habituation

There is some evidence for sex differences in habituation in the human fetus, but it is unknown whether this is due to differences in central processing (habituation) or in more peripheral processes, sensory or motor, involved in the response. This study examined whether the sex of the fetus influenced auditory habituation at 33 weeks of gestation, and whether this was due to differences in habituation or in the sensory or motor components using a set of four experiments. The first experiment found that female fetuses required significantly fewer stimulus presentations to habituate than males. The second experiment revealed no difference in the spontaneous motor behaviour of male and female fetuses. The third experiment examined auditory intensity thresholds for the stimuli used to habituate the fetus. No differences in thresholds were found between males and females, although there was inter-individual variability in thresholds. A final experiment, using stimuli individualized for that particular fetus' auditory intensity threshold, found that female fetuses habituated faster than males. In combination, the studies reveal that habituation in the human fetus is affected by sex and this is due to a difference in central 'information processing' of the stimuli rather than peripheral aspects of the response. It is argued that male and female fetuses present different neurobehavioural developmental trajectories, with females more advanced at 33 weeks than males. This study suggests that research examining prenatal behaviour should consider the factor of fetal sex. This may be particularly pertinent where there is an intention to use the results diagnostically.     

Selective attention to multidimensional auditory stimuli

Event-related brain potentials (ERPs) elicited by multidimensional auditory stimuli were recorded from the scalp in a selective-attention task. Subjects listened to tone pips varying orthogonally between two levels each of pitch, location, and duration and responded to longer duration target stimuli having specific values of pitch and location. The discriminability of the pitch and location attributes was varied between groups. By examining the ERPs to tones that shared pitch and/or locational cues with the designated target, we inferred interrelationships among the processing of these attributes. In all groups, stimuli that failed to match the target tone in an easily discriminable cue elicited only transitory ERP signs of selective processing. Tones sharing the "easy" but not the "hard" cue with the target elicited ERPs that indicated more extensive processing, but not as extensive as stimuli sharing both cues. In addition, reaction times and ERP latencies to the designated targets were not influenced by variations in the discriminability of pitch and location. This pattern of results is consistent with parallel, self-terminating models and holistic models of processing and contradicts models specifying either serial or exhaustive parallel processing of these dimensions. Both the parallel, self-terminating models and the holistic models provide a generalized mechanism for hierarchical stimulus selections that achieve an economy of processing, an underlying goal of classic, multiple-stage theories of selective attention.