Sequence effects in categorization of simple perceptual stimuli

Categorization research typically assumes that the cognitive system has access to a (more or less noisy) representation of the absolute magnitudes of the properties of stimuli and that this information is used in reaching a categorization decision. However, research on identification of simple perceptual stimuli suggests that people have very poor representations of absolute magnitude information and that judgments about absolute magnitude are strongly influenced by preceding material. The experiments presented here investigate such sequence effects in categorization tasks. Strong sequence effects were found. Classification of a borderline stimulus was more accurate when preceded by a distant member of the opposite category than by a distant member of the same category. It is argued that this category contrast effect cannot be accounted for by extant exemplar or decision-bound models of categorization. The effect suggests the use of relative magnitude information in categorization. A memory and contrast model illustrates how relative magnitude information may be used in categorization.     

Rating the similarity of simple perceptual stimuli: asymmetries induced by manipulating exposure frequency.

When judging the similarity of two stimuli, people's ratings often differ depending on the order in which the comparison is presented (A vs. B or B vs. A). Such directional asymmetries have typically been demonstrated using complex concepts that have a large number of semantic features and a standard explanation is that different sets of features are emphasized depending on the direction of the comparison. In this study, we show that directional asymmetries in the similarity of simple perceptual stimuli can be predictably manipulated merely by presenting each member of a pair with different frequency. Participants rated the similarity of color patches before and after performing an irrelevant training task in which a subset of colors was presented ten times more frequently than others. The similarity ratings after training were significantly more asymmetric than the ratings before training. We discuss the implications of these findings for models of similarity judgment and propose a computationally explicit explanation based on asymmetries in representational stability.     

Affective shifts: mood,emotion and well-being

Synthese - It is a familiar feature of our affective psychology that our moods ‘crystalize’ into emotions, and that our emotions ‘diffuse’ into moods. Providing a detailed...     

Cue utilization in emotion attribution from auditory stimuli

Electronically synthesized tone sequences with systematic manipulation of amplitude and pitch variation, pitch level and contour, tempo, envelope, and filtration were rated on emotional expressiveness. The results show that two-thirds to three-quarters of the variance in the emotion attributions can be explained by the manipulation of the acoustic cues, and that a linear model of the judges' cue utilization seems to be a good approximation to their response system. Implications for phylogenetic and ontogenetic aspects of the vocal expression of emotion and for the psychology of music are discussed.This paper is based on research supported by NIMH grant MH 19-569-01 to the first author while at the University of Pennsylvania. The authors gratefully acknowledge comments and suggestions by Paul Ekman, Ursula Scherer, and two anonymous reviewers.     

How to tell a wife from a hat: Affective feedback in perceptual categorization

How do people understand that their perception is correct? In line with the recurring idea of perception as prediction, the affective feedback account of hypotheses testing suggests that correct perceptual predictions are reinforced with positive affect. In four experiments, we tested whether correct categorization of a degraded image will lead to more positive liking ratings. The obtained findings supported the proposed approach: subjects liked the images they were able to perceive correctly more than others. Importantly, these findings were independent of the initial affective valence of stimuli. A further investigation demonstrated that this effect exists only when answers are at least moderately confident. The obtained findings add to the growing amount of literature on the role of affect in basic cognitive processing.     

Affective guidance of intelligent agents: How emotion controls cognition

How do emotions and moods color cognition? In this article, we examine how such reactions influence both judgments and cognitive performance. We argue that many affective influences are due, not to affective reactions themselves, but to the information they carry about value. The specific kind of influence that occurs depends on the focus of the agent at the time. When making evaluative judgments, for example, an agent’s positive affect may emerge as a positive attitude toward a person or object. But when an agent focuses on a cognitive task, positive affect may act like feedback about the value of one’s approach. As a result, positive affect tends to promote cognitive, relational processes, whereas negative affect tends to inhibit relational processing, resulting in more perceptual, stimulus-specific processing. As a consequence, many textbook phenomena from cognitive psychology occur readily in happy moods, but are inhibited or even absent in sad moods (149).     

Interpreting ambiguous stimuli: Separating perceptual and judgmental biases

Interpreting ambiguous situations is not a purely data-driven process but can be biased towards positive interpretations by top-down influences. The present study tries to identify the underlying processes of these top-down influences. There are two separable types of processes that can be influenced by motivational biases: A perceptual bias affects information uptake whereas a judgmental bias affects acceptance criteria for positive and negative outcomes. In the present study, motivated influences on perception and judgment were investigated with a simple color discrimination task in which ambiguous stimuli had to be classified according to their dominating color. One of two colors indicated a financial gain or a loss, whereas a third color was neutral. To separate perceptual and judgmental biases, Ratcliff’s [Ratcliff, R. (1978). A theory of memory retrieval. Psychological Review, 85, 59–108] diffusion model was employed. Results revealed motivational influences on perception and judgment.     

Misremembering emotion: Inductive category effects for complex emotional stimuli

Memories of objects are biased toward what is typical of the category to which they belong. Prior research on memory for emotional facial expressions has demonstrated a bias towards an emotional expression prototype (e.g., slightly happy faces are remembered as happier). We investigate an alternate source of bias in memory for emotional expressions – the central tendency bias. The central tendency bias skews reconstruction of a memory trace towards the center of the distribution for a particular attribute. This bias has been attributed to a Bayesian combination of an imprecise memory for a particular object with prior information about its category. Until now, studies examining the central tendency bias have focused on simple stimuli. We extend this work to socially relevant, complex, emotional facial expressions. We morphed facial expressions on a continuum from sad to happy. Different ranges of emotion were used in four experiments in which participants viewed individual expressions and, after a variable delay, reproduced each face by adjusting a morph to match it. Estimates were biased toward the center of the presented stimulus range, and the bias increased at longer memory delays, consistent with the Bayesian prediction that as trace memory loses precision, category knowledge is given more weight. The central tendency effect persisted within and across emotion categories (sad, neutral, and happy). This article expands the scope of work on inductive category effects to memory for complex, emotional stimuli.     

Individual differences in perceptual space for tactile textures: evidence from multidimensional scaling

Ratio scaling was used to obtain from 5 subjects estimates of the subjective dissimilarity between the members of all possible pairs of 17 tactile surfaces. The stimuli were a diverse array of everyday surfaces, such as corduroy, sandpaper, and synthetic fur. The results were analyzed using the multidimensional scaling (MDS) program ALSCAL. There was substantial, but not complete, agreement across subjects in the spatial arrangement of perceived textures. Scree plots and multivariate analysis suggested that, for some subjects, a two-dimensional space was the optimal MDS solution, whereas for other subjects, a three-dimensional space was indicated. Subsequent to their dissimilarity scaling, subjects rated each stimulus on each of five adjective scales. Consistent with earlier research, two of these (rough/smooth and soft/hard) were robustly related to the space for all subjects. A third scale, sticky/slippery, was more variably related to the dissimilarity data: regressed into three-dimensional MDS space, it was angled steeply into the third dimension only for subjects whose scree plots favored a nonplanar solution. We conclude that the sticky/slippery dimension is perceptually weighted less than the rough/smooth and soft/hard dimensions, materially contributing to the structure of perceptual space only in some individuals.     

Affective habituation: subliminal exposure to extreme stimuli decreases their extremity

Following a functional perspective on evaluation, the authors hypothesized that subliminal exposure to extreme stimuli (e.g., extremely negative or positive words) would lead these stimuli to be perceived as less extreme. This process--affective habituation--was tested in 4 experiments. In Experiment 1, participants were subliminally exposed to extremely positive and extremely negative words. In a subsequent explicit-judgment task, these words were rated as less extreme than extreme words that had not been presented. In Experiment 2, these results were replicated with an implicit evaluation measure. In Experiments 3 and 4, subliminal exposure to extreme positive and negative words made the words "behave" as words that are only moderately positive or negative. Several implications are discussed.     

Perceptibility of schematic face stimuli: Evidence for a perceptual Gestalt

The perceptibility of face, scrambled face, and single-feature stimuli was investigated in three experiments. Stimuli were presented tachistoscopically, followed by a visual noise mask and a forced-choice test of one of three features (eyes, nose, and mouth). In Experiment I, two processing strategies which have been proposed for word perception (involving expectancy and redundancy) were investigated for the stimuli employed here. In Experiments II and III, experimentally induced familiarity was studied for its effect on recognition and perception, and an immediate and delayed perceptual test was employed. Across all three experiments, perception of single-feature and face stimuli were consistently superior to scrambled faces; in Experiment III, differences between single features and faces were eliminated. The effects of perceptual expectancy, internal feature redundancy, familiarity, guessing biases, etc., were shown to be insufficient to account for the superiority of face to scrambled face stimuli. It was argued that the perceptibility of nonredundant features are enhanced when those features are aligned in a well-defined form class. The view that familiarity operates directly on recognitive processes but indirectly on perceptual ones was discussed.     

Affective auditory stimuli: Adaptation of the International Affective Digitized Sounds (IADS-2) for European Portuguese

In this study, we present the normative values of the adaptation of the International Affective Digitized Sounds (IADS-2; Bradley & Lang, 2007a) for European Portuguese (EP). The IADS-2 is a standardized database of 167 naturally occurring sounds that is widely used in the study of emotions. The sounds were rated by 300 college students who were native speakers of EP, in the three affective dimensions of valence, arousal, and dominance, by using the Self-Assessment Manikin (SAM). The aims of this adaptation were threefold: (1)?to provide researchers with standardized and normatively rated affective sounds to be used with an EP population; (2)?to investigate sex and cultural differences in the ratings of affective dimensions of auditory stimuli between EP and the American (Bradley & Lang, 2007a) and Spanish (Fernández-Abascal et al., Psicothema 20:104–113 2008; Redondo, Fraga, Padrón, & Piñeiro, Behavior Research Methods 40:784–790 2008) standardizations; and (3)?to promote research on auditory affective processing in Portugal. Our results indicated that the IADS-2 is a valid and useful database of digitized sounds for the study of emotions in a Portuguese context, allowing for comparisons of its results with those of other international studies that have used the same database for stimulus selection. The normative values of the EP adaptation of the IADS-2 database can be downloaded along with the online version of this article.     

The paradox of emotion attribution: explanation biases perceptual memory for emotional expressions

People who explain why ambiguous faces are expressing anger perceive and remember those faces as angrier than do people who explain why the same faces are expressing sadness. This phenomenon may be explained by a two-stage process in which language decomposes a facial configuration into its component features, which are then reintegrated with emotion categories available in the emotion explanation itself. This configural-decomposition hypothesis is consistent with experimental results showing that the explanation effect is attenuated when configural face processing is impaired (e.g., when the faces are inverted). Ironically, although people explain emotional expressions to make more accurate attributions, the process of explanation itself can decrease accuracy by leading to perceptual assimilation of the expressions to the emotions being explained.     

Dutch modality exclusivity norms: Simulating perceptual modality in space

Perceptual information is important for the meaning of nouns. We present modality exclusivity norms for 485 Dutch nouns rated on visual, auditory, haptic, gustatory, and olfactory associations. We found these nouns are highly multimodal. They were rated most dominant in vision, and least in olfaction. A factor analysis identified two main dimensions: one loaded strongly on olfaction and gustation (reflecting joint involvement in flavor), and a second loaded strongly on vision and touch (reflecting joint involvement in manipulable objects). In a second study, we validated the ratings with similarity judgments. As expected, words from the same dominant modality were rated more similar than words from different dominant modalities; but – more importantly – this effect was enhanced when word pairs had high modality strength ratings. We further demonstrated the utility of our ratings by investigating whether perceptual modalities are differentially experienced in space, in a third study. Nouns were categorized into their dominant modality and used in a lexical decision experiment where the spatial position of words was either in proximal or distal space. We found words dominant in olfaction were processed faster in proximal than distal space compared to the other modalities, suggesting olfactory information is mentally simulated as “close” to the body. Finally, we collected ratings of emotion (valence, dominance, and arousal) to assess its role in perceptual space simulation, but the valence did not explain the data. So, words are processed differently depending on their perceptual associations, and strength of association is captured by modality exclusivity ratings.     

Emergent simple discrimination in children: Preference for non-preferred stimuli

Previous research (Smeets, 1991) suggested that when given a new discrimination, children respond on the basis of physical similarity with previously discriminated stimuli. They respond to a stimulus similar to another preferred stimulus (S+ transfer) and respond away from a stimulus similar to another nonpreferred stimulus (S- transfer). When both types of transfer apply to the same stimulus, S+ transfer prevails, S+ Priority Transfer (S+PT). The present study demonstrated that S+PT also occurs when the criterion task consists of two nonpreferred stimuli. When given a choice between two previously nonpreferred stimuli, one similar and one dissimilar to other preferred stimuli, children select the first one. They do not so, however, when a nonpreferred stimulus resembling another preferred stimulus is presented with a new nonpreferred stimulus. These findings suggest that the children's preferences were not based on the physical resemblance with other (non)preferred stimuli but on the functions (S+, S-, S0) of individual stimulus components. A theoretical model is presented that accounts for all experimental data reported in the previous and present study. The model implies that discriminative responding not only results from but also determines the functional properties of individual stimulus elements.     

When 9 is not on the right: Implications from number-form synesthesia

Number-form synesthetes consciously experience numbers in spatially-defined locations. For non-synesthete individuals, a similar association of numbers and space appears in the form of an implicit mental number line as signified by the distance effect–reaction time decreases as the numerical distance between compared numbers increases. In the current experiment, three number-form synesthetes and two different non-synesthete control groups (Hebrew speaking and English speaking) performed a number comparison task. Synesthete participants exhibited a sizeable distance effect only when presented numbers were congruent with their number-form. In contrast, the controls exhibited a distance effect regardless of congruency or presentation type. The findings suggest that: (a) number-form synesthesia impairs the ability to represent numbers in a flexible manner according to task demands; (b) number-form synesthesia is a genuine tangible experience, triggered involuntarily; and (c) the classic mental number line can be more pliable than previously thought and appears to be independent of cultural-lingo direction.     

Immediate and short memory: Recall of simple auditory stimuli

Experiments were carried out on conditions affecting the successful recall of simple, non-verbalised auditory stimuli. The effectiveness of recall of a given stimulus was measured by the ability to assess the pitch of one stimulus as compared to another stimulus presented after an interval of given length. The results indicate that the storage in memory of a simple auditory stimulus is possible, even in the case of pairs of stimuli separated in time by more than 5 min. In all experiments (stimuli differing by 2 semitones or by one semitone, and equal in intensity, or differing by ± 25 dB) the curve of errors shows a sharp increase when the interval between the two stimuli is 80 sec. It is possible that this sudden deterioration in the effectiveness of recall is connected with same alteration of the mechanism of memory. It is postulated that this alteration is due to a “switch-over” from immediate memory to short-term memory. The analysis of the errors shows that in certain circumstances there is a tendency towards a marked preponderance of errors resulting from underestimation rather than from overestimation of the first stimulus. This preponderance is obtained when we have pairs of equal loudness and it is even more marked when the first stimulus is softer than the second, and it is decreases when the first stimulus is louder than the second. These results suggest that in differentiating pitches of stimuli (in the 700–2000 Hz band) presented one after the other at certain fixed intervals of time, we are to find a phenomenon analogous to the classic time error found in estimations of loudness.