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Behavioral responses to a perceptual stimulus are typically faster with repeated exposure to the stimulus (behavioral priming). This implicit learning mechanism is critical for survival but impaired in a variety of neurological disorders, including Alzheimer's disease. Many studies of the neural bases for behavioral priming have encountered an interesting paradox: in spite of faster behavioral responses, repeated stimuli usually elicit weaker neural responses (repetition suppression). Several neurophysiological models have been proposed to resolve this paradox, but noninvasive techniques for human studies have had insufficient spatial-temporal precision for testing their predictions. Here, we used the unparalleled precision of electrocorticography (ECoG) to analyze the timing and magnitude of task-related changes in neural activation and propagation while patients named novel vs repeated visual objects. Stimulus repetition was associated with faster verbal responses and decreased neural activation (repetition suppression) in ventral occipito-temporal cortex (VOTC) and left prefrontal cortex (LPFC). Interestingly, we also observed increased neural activation (repetition enhancement) in LPFC and other recording sites. Moreover, with analysis of high gamma propagation we observed increased top-down propagation from LPFC into VOTC, preceding repetition suppression. The latter results indicate that repetition suppression and behavioral priming are associated with strengthening of top-down network influences on perceptual processing, consistent with predictive coding models of repetition suppression, and they support a central role for changes in large-scale cortical dynamics in achieving more efficient and rapid behavioral responses.

Object perception is inherently multidimensional: information about color, material, texture and shape all guide how we interact with objects. We developed a paradigm that quantifies how two object properties (color and material) combine in object selection. On each experimental trial, observers viewed three blob-shaped objects—the target and two tests—and selected the test that was more similar to the target. Across trials, the target object was fixed, while the tests varied in color (across 7 levels) and material (also 7 levels, yielding 49 possible stimuli). We used an adaptive trial selection procedure (Quest+) to present, on each trial, the stimulus test pair that is most informative of underlying processes that drive selection. We present a novel computational model that allows us to describe observers’ selection data in terms of (1) the underlying perceptual stimulus representation and (2) a color-material weight, which quantifies the relative importance of color vs. material in selection. We document large individual differences in the color-material weight across the 12 observers we tested. Furthermore, our analyses reveal limits on how precisely selection data simultaneously constrain perceptual representations and the color-material weight. These limits should guide future efforts towards understanding the multidimensional nature of object perception., Author summary Much is known about how the visual system extracts information about individual object properties, such as color or material. Considerably less is known about how percepts of these properties interact to form a multidimensional object representation. We report the first quantitative analysis of how perceived color and material combine in object selection, using a task designed to reflect key aspects of how we use vision in real life. We introduce a computational model that describes observers’ selection behavior in terms of (1) how objects are represented in an underlying subjective perceptual color-material space and (2) how differences in perceived object color and material combine to guide selection. We find large individual differences in the degree to which observers select objects based on color relative to material: some base their selections almost entirely on color, some weight color and material nearly equally, and others rely almost entirely on material. A fine-grained analysis clarifies the limits on how precisely selection data may be leveraged to simultaneously understand the underlying perceptual representations on one hand and how the information about perceived color and material combine on the other. Our work provides a foundation for improving our understanding of visual computations in natural viewing.

The current study investigated whether or not the physical aspect of stimulus size has an effect on neuronal correlates of feedback processing. A time estimation task was administered applying three different feedback stimulus categories: small, middle, and large size stimuli. Apart from early visual ERPs such as P1 and N1 components, later feedback processing stages were also affected by the size of feedback stimuli. In particular, small size stimuli compared to middle and large size ones led to diminished amplitudes in both FRN and P300 components, despite intact discrimination between negative and positive outcomes in these two ERPs. In contrast, time estimation performance was not influenced by feedback size. The current results indicate that small size feedback stimuli were perceived as less salient and hence were processed less deeply than the others. This suggests that future feedback studies could manipulate feedback salience simply by presenting differently sized feedback stimuli, at least when the focus lies on FRN and P300 amplitude variation.

The present study addressed the question of whether temporal preparation influences perceptual stimulus processing in a selective manner. In three visual search experiments, we examined whether temporal preparation aids spatial selection and thus reduces distraction caused by the onset of a task-irrelevant item. In each trial, participants had to detect a target amongst five non-targets and report a basic feature of the target. In some trials, an additional task-irrelevant singleton item (abrupt onset) appeared on the screen which distracted attention away from the target. To manipulate the degree of distraction, we varied the spatial distance and the stimulus-onset asynchrony between target and singleton. Temporal preparation for the target varied by means of constant foreperiods of different lengths. Though we observed overall faster responding in the case of high temporal preparation in all three experiments, temporal preparation did not reduce spatial distraction by the abrupt onset, even when the spatial position of the target was predictable. In sum, this pattern of results does not provide support for an influence of temporal preparation on spatial selection. Instead, it indicates that temporal preparation affects early visual processing in a non-selective manner.

Would it be helpful to inform a driver about when a conflicting traffic situation is going to occur? We tested whether temporal orienting of attention could enhance executive control to select among conflicting stimuli and responses. Temporal orienting was induced by presenting explicit cues predicting the most probable interval for target onset, which could be short (400 ms) or long (1,300 ms). Executive control was measured both by flanker and Simon tasks involving conflict between incompatible responses and by the spatial Stroop task involving conflict between perceptual stimulus features. The results showed that temporal orienting facilitated the resolution of perceptual conflict by reducing the spatial Stroop effect, whereas it interfered with the resolution of response conflict by increasing flanker and Simon effects. Such opposite effects suggest that temporal orienting of attention modulates executive control through dissociable mechanisms, depending on whether the competition between conflicting representations is located at perceptual or response levels.

The slope of the distance-time relationship from maximal 200 and 400 m bouts (S(200-400)) has been increasingly employed for setting training intensities in swimming. However, physiological and mechanical responses at this speed are poorly understood. Thus, this study investigated blood lactate, heart rate (HR), stroke rate (SR), stroke length (SL) and RPE responses to an interval swimming set at S(200-400) in trained swimmers. In a 50-m pool, twelve athletes (16.5+/-1.2 yr, 176+/-7 cm, 68.4+/-5.4 kg, and 7.8+/-2.5% body fat) performed maximal 200 and 400 m crawl trials for S(200-400) determination (1.28+/-0.05 m/s). Thereafter, swimmers were instructed to perform 5 x 400 m at this speed with 1.5 min rest between repetitions. Three athletes could not complete the set (exhaustion at 21.0+/-3.1 min). For the remaining swimmers (total set duration=32.0+/-1.3 min) significant increases (p

Generating a detailed, memory-based description of a non-verbal perceptual stimulus can impair later recognition of that stimulus—an effect termed verbal overshadowing (VO). After viewing a face for 10 seconds, half the participants wrote a description of it; the others completed an unrelated task. Participants then either imagined their proximal or distant future, or completed an unrelated task. Following a recognition test for the face previously presented, all the 75 participants attempted to solve three insight problems. A robust VO effect was observed for participants who imagined their proximal future; that is, providing a description of the face impaired their later recognition of that face. In contrast, those who imagined their distal future showed no such impairment. Furthermore, distal imagining participants solved more insight problems compared to proximal, and control condition participants. The results of this study provide support for a processing shift interpretation of VO. Copyright © 2007 John Wiley & Sons, Ltd.

Previous research suggests that the repeated performance of approach and avoidance (AA) actions in response to a stimulus causes changes in stimulus evaluations. Kawakami, Phills, Steele, and Dovidio (2007) and Jones, Vilensky, Vasey, and Fazio (2013) provided evidence that these AA training effects occur even when stimuli are presented only subliminally. We also examined whether reliable AA training effects can be observed with subliminal stimulus presentations but added more sensitive checks of perceptual stimulus discriminability. Three experiments, including a direct replication of the study by Kawakami et al. (2007), failed to provide any evidence for effects of subliminal AA training on implicit or explicit evaluations. Bayesian analyses indicated that our data provide robust evidence that subliminal AA training does not cause changes in evaluations. In contrast, we observed changes in evaluations when participants were provided with (either correct or incorrect) information about the stimulus-action contingencies in the subliminal AA training task and when participants performed a supraliminal AA training task that allowed participants to detect these contingencies. These findings support the idea that contingency awareness is necessary for the occurrence of AA training effects.

Motivated by the Weber’s Law, this paper proposes an efficient and robust shape descriptor based on the perceptual stimulus model, called Weber’s Law Shape Descriptor (WLSD). It is based on the theory that human perception of a pattern depends not only on the change of stimulus intensity, but also on the original stimulus intensity. Invariant to scale and rotation is the intrinsic properties of WLSD. As a global shape descriptor, WLSD has far lower computation complexity while is as discriminative as state-of-art shape descriptors. Experimental results demonstrate the strong capability of the proposed method in handling shape retrieval.

Threatening, friendly, and neutral faces were presented to test the hypothesis of the facilitated perceptual processing of threatening faces. Dense sensor event-related brain potentials were measured while subjects viewed facial stimuli. Subjects had no explicit task for emotional categorization of the faces. Assessing early perceptual stimulus processing, threatening faces elicited an early posterior negativity compared with nonthreatening neutral or friendly expressions. Moreover, at later stages of stimulus processing, facial threat also elicited augmented late positive potentials relative to the other facial expressions, indicating the more elaborate perceptual analysis of these stimuli. Taken together, these data demonstrate the facilitated perceptual processing of threatening faces. Results are discussed within the context of an evolved module of fear (A. Öhman & S. Mineka, 2001).

In this article, we examine how emotional and perceptual stimulus factors influence visual search efficiency. In an initial task, we run a visual search task, using a large number of target/distractor emotion combinations. In two subsequent tasks, we then assess measures of perceptual (rated and computational distances) and emotional (rated valence, arousal and potency) stimulus properties. In a series of regression analyses, we then explore the degree to which target salience (the size of target/distractor dissimilarities) on these emotional and perceptual measures predict the outcome on search efficiency measures (response times and accuracy) from the visual search task. The results show that both emotional and perceptual stimulus salience contribute to visual search efficiency. The results show that among the emotional measures, salience on arousal measures was more influential than valence salience. The importance of the arousal factor may be a contributing factor to contradictory history of results within this field.

Many psychologists and philosophers believe that the close correlation between human language and human concepts makes the attribution of concepts to nonhuman animals highly questionable. I argue for a three-part approach to attributing concepts to animals. The approach goes beyond the usual discrimination tests by seeking evidence for self-monitoring of discrimination errors. Such evidence can be collected without relying on language and, I argue, the capacity for error-detection can only be explained by attributing a kind of internal representation that is reasonably identified as a concept. Thus I hope to have shown that worries about the empirical intractability of concepts in languageless animals are misplaced.

Some stimuli can orient attentional resources and access awareness even if they appear outside the focus of voluntary attention. Stimuli with low-level perceptual salience and stimuli with an emotional content can modulate attention independently of voluntary processes. In Experiment 1, we used a spatial cuing task to investigate whether stimuli that are controlled for their perceptual salience can modulate the rapid orienting of attention based exclusively on their affective relevance. Affective relevance was manipulated through a Pavlovian conditioning paradigm in which an arbitrary and affectively neutral perceptual stimulus was associated with a primary reward (i.e., a chocolate odor). Results revealed that, after conditioning, attentional resources were rapidly oriented toward the stimulus that was previously associated with the reward. In Experiment 2, we used the very same conditioning procedure, but we devaluated the reward after conditioning for half of the participants through a sensory-specific satiation procedure. Strikingly, when the reward was devaluated, attention was no longer oriented toward reward-associated stimuli. Our findings therefore suggest that reward associations rapidly modulate visual processing independently of both voluntary processing and the perceptual salience of the stimulus. This supports the notion that stimuli associated with primary rewards modulate rapid attention orienting on the basis of the affective relevance of the stimulus.

Color is a ubiquitous perceptual stimulus, yet relatively little empirical and even less theoretical work exists on color and psychological functioning. The research that has been conducted has tended to lack the scientific precision and rigor evident in other areas of inquiry in psychology. In response, we have set out to develop a general model of color and psychological functioning—color-in-context theory—which we present herein. We also overview several lines of empirical work that have emerged from this theoretical framework, starting with research on red in achievement contexts, moving on to research on red in affiliation contexts, and concluding with research on other colors in other contexts. In addition, we articulate the need to carefully attend to the fact that color comprises three attributes—hue, lightness, and chroma—in creating color manipulations in experimental work. We close by highlighting the conceptual, empirical, and practical implications of viewing color as a functional, as well as aesthetic, stimulus, and by sounding the call for more research in this important yet overlooked area.

P. A. van der Helm and E. L. J. Leeuwenberg (1996) outlined a holographic account of figural goodness of a perceptual stimulus. The theory is mathematically precise and can be applied to a broad spectrum of empirical data. The authors argue, however, that the account is inadequate on both theoretical and empirical grounds, The theoretical difficulties concern the internal consistency of the account and its reliance on unspecified auxiliary assumptions. The account also makes counterintuitive empirical predictions, which do not fit past data or the results of a series of new experimental studies.

In a series of experiments the learning of tactile speech has been investigated. The experiment to be reported was concerned with the role of physiological measures in interpreting perceptual stimulus processing. Five untrained participants underwent seven sessions of an identification test on six tactile syllables. The electrocutaneous stimuli representing three fortis and three lenis fricatives followed by a schwa were constructed as dynamical patterns and delivered to the left forearm (place of articulation from labial to velar: distal to proximal stimulation, fortis patterns moving faster than lenis patterns). Correct and incorrect answers as well as skin conductance reactions (SCR) and eye blinks were registered. For statistical analysis SCR‐peak amplitudes and blink rate (BR) were calculated from stimulus onset to end of interstimulus interval. A MANOVA on SCR and blink rate shows significantly decreasing SCRs and increasing BRs over sessions. BR is higher in the case of correct identification. On t...

The judgmental accuracy was measured in situations where absolute judgments about various categories on a response continuum are required. Instead of presenting a perceptual stimulus to which a subject must assign a numerical response, he is given a number from 1 to N and must then generate a corresponding motor response. The amounts of transmitted information in producing vocal sounds varying in only one dimension, either their intensity or duration, are compared to the amounts in identifying analogous signals. It has been concluded that decoding and encoding processes are similarly limited in information processing. By studying the anchor effects, it has also been hypothesized that every categorial judgment is binary.

The net speed of arm movement made in response to sounds of 45, 65 and 85 db. loudness was measured by chronoscope. Reaction time was excluded. Thirty-six college men were tested. In another experiment, the force of successive contractions of the forearm muscles in response to serial auditory stimuli spaced 5 sec. apart was measured by a recording dynamometer. In both experiments there was a balanced order of presenting the three stimulus intensities. In general, the louder sounds produced faster arm movements and stronger contractions of the muscles. In explanation, it is postulated that greater perceived stimulus intensity results in stronger excitation of the pyramidal tracts and consequently more forceful muscular contractions.

Systematic measurements of perceptual learning were performed in the presence of external or stimulus noise. In the new external noise method (Dosher, B, & Lu, Z.-L. (1997). In6estigati6e Ophthalmology and Visual Science, 38, S687; Lu, Z.-L., & Dosher, B. (1998). Vision Research, 38, 1183‐1198), increasing amounts of external noise (white Gaussian random noise) is added to the visual stimulus in order to identify mechanisms of perceptual learning. Performance improved (threshold contrast was reduced) over days of practice on a peripheral orientation discrimination task—labelling Gabor patches as tilted slightly to the right or left. Practice improvements were largely specific to the trained quadrant of the display. Performance improved at all levels of external noise. The external noise method and perceptual template model (PTM) of the observer identifies the mechanism(s) of performance improvements as due to stimulus enhancement, external noise exclusion ,o rinternal noise suppression. The external noise method was further extended by measuring thresholds at two threshold performance levels, allowing identification of mixtures in the PTM model. Perceptual learning over 8‐10 days improved the filtering or exclusion of external noise by a factor of two or more, and improved suppression of additive internal noise—equivalent to stimulus enhancement—by 50% or more. Coupled improvements in external noise exclusion and stimulus enhancement in the PTM model may reflect channel weighting. Perceptual learning may not reflect neural plasticity at the level of basic visual channels, nor cognitive adjustments of strategy, but rather plasticity at an intermediate level of weighting inputs to decision. © 1999 Elsevier Science Ltd. All rights reserved.

Instead of presenting a perceptual stimulus to which a subject must assign numerical response, he is given a number from 1 to N and must then generate corresponding motor response. The amounts of information transmitted in producing acoustical signals varying in only one dimension, either their SPL (between 50 and 105 dB) or their frequency (between 50 and 6000 Hz), are compared to the amounts of transmitted information in identifying analogous signals.

Publisher Summary This chapter discusses cerebral specialization in deaf individuals. In hearing individuals, there is a division of labor between the two hemispheres. It has been demonstrated that the direction of hemispheric advantage for the recognition of complex perceptual material may depend upon somewhat subtle changes in the nature of the stimuli presented, which may affect the type of processing utilized. Similarly, the hemispheric advantage shown for the recognition of sign language may differ with various types of stimuli and depend upon the type of processing required for the recognition of the stimuli presented. Therefore, individuals may show a right-hemisphere advantage when the signs can be recognized predominantly on the basis of the configuration of the perceptual stimulus but may show a left-hemisphere advantage when analytic processing is required for the recognition of signs. Therefore, the hemisphere that shows an advantage in processing an individual sign may depend upon particular properties of the sign itself, such as the type of movement involved and the type of visual information presented for recognition.

Summary In recent years there has been an increasing body of evidence attempting to validate the hypothesis that subliminal stimuli may affect behavior. Supposedly, a faint perceptual stimulus may affect behavior even when this stimulus is below threshold, Gudmund and his associates (1959) studied the effects of subliminal verbal stimuli and reported that the difference between meanings registered below a recognition threshold can affect conscious thoughts. In an investigation of the effects of subliminal stimuli of aggressive content upon conscious cognition, Eagle (1959) notes that stimuli that are not conscious and that are non-aggressive affected subjects' impressions of a consciously perceived stimulus. These findings support the contention that stimuli which are not consciously perceived or directly experienced can influence cognition. This study was undertaken in an attempt to investigate the effect of noxious subliminal stimuli on the modification of attitudes toward alcoholism. It is hypothesized that the programmed exposure of noxious subliminal stimuli will modify attitudes toward alcoholism. It is hoped that findings from this pilot study will shed some light on the nature of the effect of subliminal stimulation on the modification of attitudes toward alcoholism.