Effects Of Stimulus Complexity Research Articles

Effect of stimulus complexity on psychometric functions

Factors such as semantic and syntactic context, predictability, talker characteristics, background noise characteristics, and spatial differences between the target and maskers play major role in identifying speech in complex listening environments. Here, we present psychometric properties of two closed set speech corpus: (1) co-ordinate response measure (CRM) and (2) Boston University Corpus (BUC) obtained from a group of fifty young normal-hearing, listeners. CRM sentences are of the form “Ready CALLSIGN go to a COLOR NUMBER now” and BUC sentences are of the form “NAME VERB NUMBER ADJECTIVE NOUN.” Method of constant stimuli was used to obtain psychometric functions for the two corpora in the presence of speech and speech shaped noise. One half of the participants were presented the stimuli at a constant level (20 dB SL), while it was presented at comfortable listening levels for the half. The effect of the stimulus complexity, presentation level, and spatial configuration of the target and noise on the identification thresholds and the shape of the psychometric functions will be discussed.

Effect of stimulus complexity on the phonemic restoration effect

The phonemic restoration effect is the increase in speech intelligibility when the silent portions of the interrupted speech were replaced by a noisethat is louder than the speech signal itself. Previous research has demonstrated that the phonemic restoration effect is maximum when the interruption rate is between 1.5 and 3 Hz with a 50% duty cycle. Here we present phonemic restoration results obtained using five different speech corpora varying in stimulus complexity (least complex – most complex): (1) Callsign Acquisition Test (CAT); (2) Co-ordinate Response Measure (CRM); (3) Boston University Corpus (BUC); (4) IEEE sentences; and (5) R-PRESTO obtained from a group of young normal-hearing, listeners. Interruption rates of 2 Hz and 3 Hz were used and speech shaped noise was used to fill the silent interruptions. Initial analyses of the data revealed that the phonemic restoration effect was absent for the least complex stimuli (CAT) because of ceiling effects and the amount of restoration increased as the complexity of the stimulus increased. The effect of interruption rate and signal-to-noise ratio between the speech and noise on the phonemic restoration effect will also be discussed.

Visual working memory for connected 3D objects: effects of stimulus complexity, dimensionality and connectivity

Visual working memory (VWM) is typically measured using arrays of two-dimensional isolated stimuli with simple visual identities (e.g., color or shape), and these studies typically find strong capacity limits. Science, technology, engineering and mathematics (STEM) experts are tasked with reasoning with representations of three-dimensional (3D) connected objects, raising questions about whether those stimuli would be subject to the same limits. Here, we use a color change detection task to examine working memory capacity for 3D objects made up of differently colored cubes. Experiment 1a shows that increasing the number of parts of an object leads to less sensitivity to color changes, while change-irrelevant structural dimensionality (the number of dimensions into which parts of the structure extend) does not. Experiment 1b shows that sensitivity to color changes decreases similarly with increased complexity for multipart 3D connected objects and disconnected 2D squares, while sensitivity is slightly higher with 3D objects. Experiments 2a and 2b find that when other stimulus characteristics, such as size and visual angle, are controlled, change-irrelevant dimensionality and connectivity have no effect on performance. These results suggest that detecting color changes on 3D connected objects and on displays of isolated 2D stimuli are subject to similar set size effects and are not affected by dimensionality and connectivity when these properties are change-irrelevant, ruling out one possible explanation for scientists’ advantages in storing and manipulating representations of complex 3D objects.

An Experimental Study on Tracking Identity of Moving Shapes: Do Stimulus Complexity and Familiarity Affect Tracking Accuracy of Male and Female Students?

The current study explored the effects of stimulus complexity and familiarity on tracking accuracy between male and female postgraduate students in Malaysia. Since online courses are not restricted by location, the convenience of recording classes has become a steady trend, especially during the COVID-19 period. However, some are also skeptical about the efficacy of online teaching and learning through the digital environment and believe that the stimulus generated on these foundations will result in undesirable consequences (Dhawan, 2020). As student attention determines their tracking accuracy, external factors like stimulus complexity and familiarity tend to be an obstacle for students to be attentive. In this quantitative experimental study named "Simon Effect", 24 postgraduate students (12 males and 12 females) in a Malaysian public research university were used as samples to test whether or not gender plays a role in tracking accuracy. Results show that gender does not influence the tracking accuracy of postgraduate students. At the same time, the stimulus complexity and familiarity do influence the tracking accuracy of the postgraduate students. The implication of the study lies in promoting the teaching and learning sessions not only for a postgraduate student but for all the students in different educational levels during the COVID-19 period and maximizing the educational outcomes.

What is the Effect of Stimulus Complexity on Attention to Repeating and Changing Information in Autism?

Slower habituation to repeating stimuli characterises Autism, but it is not known whether this is driven by difficulties with information processing or an attentional bias towards sameness. We conducted eye-tracking and presented looming geometrical shapes, clocks with moving arms and smiling faces, as two separate streams of stimuli (one repeating and one changing), to 7–15 years old children and adolescents (n = 103) with Autism, ADHD or co-occurring Autism+ADHD, and neurotypical children (Study-1); and to neurotypical children (n = 64) with varying levels of autistic traits (Study-2). Across both studies, autistic features were associated with longer looks to the repeating stimulus, and shorter looks to the changing stimulus, but only for more complex stimuli, indicating greater difficulty in processing complex or unpredictable information.

Age differences in item selection behaviors and subsequent memory for new foreign language vocabulary: Evidence for a region of proximal learning heuristic.

We examined younger and older adults' item selection behaviors to assess heuristics for self-regulating learning of English meanings of Chinese characters varying widely in figural complexity. Two study-test trials were used to assess whether (a) item selection behaviors on the first study opportunity would show evidence for a difficulty-based heuristic as posited by Metcalfe's (2002) region of proximal learning (RPL) theory, or alternatively, influences of habitual English-language reading order (i.e. left-to-right, top-to-bottom); (b) whether second-trial selection behaviors were better predicted by RPL or by the discrepancy reduction model (DRM; Dunlosky & Hertzog, 1998); and (c) whether Trial 1 test performance would alter Trial 2 study in a manner predicted by RPL. DRM stipulates people select any item for study at Trial 2 that was not previously recalled. RPL states that people study only items they believe they can learn, avoiding complex items above their subjective RPL. Stimuli were 36 Chinese-English vocabulary pairs randomly presented in six 2 × 3-element grids. Both habitual reading order and stimulus complexity at Trial 1 affected order of study, with participants of both age groups manifesting a preference to study less complex characters. However, older adults showed larger effects of stimulus complexity whereas younger adults had larger effects of habitual reading order. At Trial 2, older adults showed a greater tendency to avoid studying the most complex Chinese characters, consistent with RPL, which contributed to their lower rates of vocabulary acquisition. Older adults' more conservative RPLs appeared to constrain their degree of self-regulated learning. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Stimulus Complexity and Mouse Strain Drive Escalation of Operant Sensation Seeking Within and Across Sessions in C57BL/6J and DBA/2J Mice.

Sensation seeking is a heritable trait that is genetically correlated with substance use; the shared genetic mechanisms underlying these traits are largely unknown. The relationship of sensation seeking and substance use has practical importance because discovering genes that drive sensation seeking can reveal genes driving substance use, and quantification of sensation seeking in mice is higher throughput and less technically challenging than quantification of volitional drug use. In order to fully understand the genetic mechanisms driving sensation seeking, it is critical to first understand the nongenetic factors driving sensation seeking. In the present study, we used the operant sensation seeking paradigm to assess the effects of stimulus complexity on sensation seeking in C57BL/6J and DBA/2J mice. These strains are the founders of the BXD recombinant inbred mouse panel which enables the discovery of genes driving phenotypic variation. This study led to four principal conclusions. First, all sensory stimuli used in the study, regardless of complexity or number of stimulus modalities, served as reinforcers for C57BL/6J and DBA/2J mice. Second, for both C57BL/6J and DBA/2J mice, sensation seeking for a high complexity sensory stimulus was significantly greater than sensation seeking for a low complexity sensory stimulus. Third, for both C57BL/6J and DBA/2J mice, sensation seeking escalated significantly within-session when a multimodal sensory stimulus of medium or high complexity was used but not when a unimodal sensory stimulus of low complexity was used. Finally, both the magnitude of sensation seeking and the magnitude of within-session escalation of sensation seeking were significantly greater in mice from the DBA/2J strain relative to mice from the C57BL/6J strain. Collectively, these findings indicate that stimulus complexity and genetic background drive escalation of operant sensation seeking within and across sessions, and that the BXD recombinant inbred mouse panel can be used to discover the genetic mechanisms underlying these phenomena.

Gradual formation of visual working memory representations of motion directions.

Although it is well accepted that the formation of visual working memory (VWM) representations from simple static features is a rapid and effortless process that completes within several hundred milliseconds, the storage of motion information in VWM within that time scale can be challenging due to the limited processing capacity of the visual system. Memory formation can also be demanding especially when motion stimuli are visually complex. Here, we investigated whether the formation of VWM representations of motion direction is more gradual than that of static orientation and examined the effects of stimulus complexity on that process. To address these issues, we examined how the number and the precision of stored items in VWM develop over time by using a continuous report procedure. Results showed that while a viewing duration of several seconds was required for the successful storage of multiple motion directions in VWM regardless of motion complexity, the accumulation of memory precision was much slower when the motion stimulus was visually complex (Experiments 1 & 2). Additional experiments showed that the difference in memory performance for simple and complex motion stimuli cannot be explained by differences in signal-to-noise levels of the stimulus (Experiment 3). These results demonstrate remarkable temporal limitations in the formation of VWM representations for dynamic objects, and further show how this process is affected by stimulus properties such as visual complexity and signal-to-noise levels.

The effects of stimulus complexity and conceptual fluency on aesthetic judgments of abstract art: Evidence for a default–interventionist account

ABSTRACTWe report an experiment investigating how stimulus complexity and conceptual fluency (i.e., the ease of deriving meaning) influence aesthetic liking judgments for abstract artworks. We presented participants with paintings at two levels of complexity (high vs. low) and five levels of conceptual fluency (determined from a prior norming study) and requested separate ratings of beauty and creativity. Our predictions were derived from the PIA Model (Pleasure-Interest Model of Aesthetic Liking), which views aesthetic preferences as being formed by two, distinct fluency-based processes: an initial, automatic, stimulus-driven, default process and a subsequent, perceiver-driven deliberative process. A key trigger for deliberative processing is assumed to be disfluency at the default stage, as caused by factors such as visual complexity. We predicted that complexity and conceptual fluency would interact in determining aesthetic liking, with people preferring complex stimuli, but only when these are relatively easy to process conceptually. Our results supported this prediction for beauty judgments, although creativity judgments showed a curiously uniform profile. Nevertheless, the predictive capacity of the PIA Model in relation to beauty judgments attests to the explanatory strength of this default–interventionist theory of aesthetic liking. We conclude by noting important parallels between the PIA Model and the Revised Optimal Innovation Hypothesis, which likewise has broad reach in explaining how defaultness and non-defaultness affect pleasure across a range of linguistic and pictorial stimuli.

The effects of stimulus complexity on the preattentive processing of self-generated and nonself voices: An ERP study

The ability to differentiate one's own voice from the voice of somebody else plays a critical role in successful verbal self-monitoring processes and in communication. However, most of the existing studies have only focused on the sensory correlates of self-generated voice processing, whereas the effects of attentional demands and stimulus complexity on self-generated voice processing remain largely unknown. In this study, we investigated the effects of stimulus complexity on the preattentive processing of self and nonself voice stimuli. Event-related potentials (ERPs) were recorded from 17 healthy males who watched a silent movie while ignoring prerecorded self-generated (SGV) and nonself (NSV) voice stimuli, consisting of a vocalization (vocalization category condition: VCC) or of a disyllabic word (word category condition: WCC). All voice stimuli were presented as standard and deviant events in four distinct oddball sequences. The mismatch negativity (MMN) ERP component peaked earlier for NSV than for SGV stimuli. Moreover, when compared with SGV stimuli, the P3a amplitude was increased for NSV stimuli in the VCC only, whereas in the WCC no significant differences were found between the two voice types. These findings suggest differences in the time course of automatic detection of a change in voice identity. In addition, they suggest that stimulus complexity modulates the magnitude of the orienting response to SGV and NSV stimuli, extending previous findings on self-voice processing.

Differences in sensory processing of German vowels and physically matched non-speech sounds as revealed by the mismatch negativity (MMN) of the human event-related brain potential (ERP)

We compared processing of speech and non-speech by means of the Mismatch Negativity (MMN). For this purpose, the MMN elicited by vowels was compared to those elicited by two non-speech stimulus types: spectrally rotated vowels, having the same stimulus complexity as the speech stimuli, and sounds based on the bands of formants of the vowels, representing non-speech stimuli of lower complexity as compared to the other stimulus types. This design allows controlling for effects of stimulus complexity when comparing neural correlates of processing speech to non-speech. Deviants within a modified multi-feature design differed either in duration or spectral property. Moreover, the difficulty to discriminate between the standard and the two deviants was controlled for each stimulus type by means of an additional active discrimination task. Vowels elicited a larger MMN compared to both non-speech stimulus types, supporting the concept of language-specific phoneme representations and the role of the participants’ prior experience.

Stimulus complexity effects on the event-related potentials to task-irrelevant stimuli

The effects of irrelevant stimuli complexity on event-related potentials were investigated in 3 conditions using both auditory and visual oddball tasks. In Conditions 1 and 2, simple standard and target stimuli were presented in series with complex, identical (Condition 1) or variable (Condition 2), task-irrelevant stimuli. In Condition 3, complex standards and targets were presented with simple, identical, task-irrelevant stimuli. In Conditions 1 and 2, but not Condition 3, the irrelevant stimuli elicited the P3a component in both auditory and visual modalities and the N2b component in the visual modality. While we found that variable, irrelevant stimuli evoked larger P3a in the auditory modality compared with identical irrelevant stimuli, we observed the opposite effect in the visual modality. These results suggest that stimuli rareness and irrelevance are not sufficient for eliciting P3a. This component is only elicited by irrelevant stimuli that are at least as complex as the task-related stimuli.

Emotional picture and word processing: an FMRI study on effects of stimulus complexity.

Neuroscientific investigations regarding aspects of emotional experiences usually focus on one stimulus modality (e.g., pictorial or verbal). Similarities and differences in the processing between the different modalities have rarely been studied directly. The comparison of verbal and pictorial emotional stimuli often reveals a processing advantage of emotional pictures in terms of larger or more pronounced emotion effects evoked by pictorial stimuli. In this study, we examined whether this picture advantage refers to general processing differences or whether it might partly be attributed to differences in visual complexity between pictures and words. We first developed a new stimulus database comprising valence and arousal ratings for more than 200 concrete objects representable in different modalities including different levels of complexity: words, phrases, pictograms, and photographs. Using fMRI we then studied the neural correlates of the processing of these emotional stimuli in a valence judgment task, in which the stimulus material was controlled for differences in emotional arousal. No superiority for the pictorial stimuli was found in terms of emotional information processing with differences between modalities being revealed mainly in perceptual processing regions. While visual complexity might partly account for previously found differences in emotional stimulus processing, the main existing processing differences are probably due to enhanced processing in modality specific perceptual regions. We would suggest that both pictures and words elicit emotional responses with no general superiority for either stimulus modality, while emotional responses to pictures are modulated by perceptual stimulus features, such as picture complexity.

Inducing closing-in phenomenon in healthy young adults: the effect of dual task and stimulus complexity on drawing performance

Closing-in (CI) is the tendency to act very close to the model in tasks such as drawing, 3D construction, gesture imitation, or writing. Closing-in is observed in degenerative and focal brain diseases, but also in normally developing children. In the present paper, three experiments were conducted to evaluate whether CI can be triggered during a copying task in normal young adults by increasing stimulus complexity and attentional load. Participants were required to copy complex lines in one of three conditions: without interfering activities (baseline), during counting, or during execution of a 2-back short-term memory task. In Experiment 1, participants were required to reproduce horizontally aligned stimuli, starting from a dot placed below each stimulus and proceeding from left to right; in Experiment 2, stimuli were again horizontally aligned, but the starting dot was placed above each stimulus, and writing proceeded from right to left; in Experiment 3, stimuli were aligned vertically and copying proceeded in upward direction. Results from all experiments showed that when normal young adults are engaged in an attentional-demanding concurrent activity, they tend to approach to the model, whereas the effect of stimulus complexity disappeared with unusual writing direction (Experiments 2 and 3). These findings demonstrate that even in normal young adults, a reduction in available attentional resources can release an attraction toward the model.

Auditory‐musical processing in autism spectrum disorders: a review of behavioral and brain imaging studies

Autism spectrum disorder (ASD) is a complex neurodevelopmental condition characterized by atypical social and communication skills, repetitive behaviors, and atypical visual and auditory perception. Studies in vision have reported enhanced detailed ("local") processing but diminished holistic ("global") processing of visual features in ASD. Individuals with ASD also show enhanced processing of simple visual stimuli but diminished processing of complex visual stimuli. Relative to the visual domain, auditory global-local distinctions, and the effects of stimulus complexity on auditory processing in ASD, are less clear. However, one remarkable finding is that many individuals with ASD have enhanced musical abilities, such as superior pitch processing. This review provides a critical evaluation of behavioral and brain imaging studies of auditory processing with respect to current theories in ASD. We have focused on auditory-musical processing in terms of global versus local processing and simple versus complex sound processing. This review contributes to a better understanding of auditory processing differences in ASD. A deeper comprehension of sensory perception in ASD is key to better defining ASD phenotypes and, in turn, may lead to better interventions.

P32-10 The effects of stimulus complexity on viewers' initial brain response and subsequent viewing duration

P32-10 The effects of stimulus complexity on viewers' initial brain response and subsequent viewing duration

The effects of stimulus complexity and meaningfulness on the anterior N2, visual exploration, and subjective interest of the viewer

The effects of stimulus complexity and meaningfulness on the anterior N2, visual exploration, and subjective interest of the viewer

The Effects of Geographic Familiarity and Map Complexity on Mental Rotation

The present study examined the effects of stimulus complexity and geographic familiarity upon mental rotation while simultaneously engaging participants in a simulated flight task. Nineteen licensed pilots (16 men and 3 women) participated in a mental rotation task. Results indicated a piecemeal strategy was used with maps representing an unfamiliar geographic area. Further, an exploratory analysis indicated that unfamiliar condition participants may have used a strategy described by Loftus (1978), in which two rotations are performed - the first from the cue orientation to the nearest cardinal direction, and the second from the cardinal direction to the target orientation. Those in the familiar condition used a nonrotational strategy (i.e., a piecemeal comparison between the presented map and their cognitive map) to perform the rotation task. Unfamiliar condition flight performance was more affected by the experimental manipulations. This suggests that cognitive transformations performed on unfamiliar geographic images are cognitively more demanding than those using familiar geographic images.

Perceptual equivalence between vision and touch is complexity dependent

We experience the shape of objects in our world largely by way of our vision and touch but the availability and integration of information between the senses remains an open question. The research presented in this article examines the effect of stimulus complexity on visual, haptic and crossmodal discrimination. Using sculpted three-dimensional objects whose features vary systematically, we perform a series of three experiments to determine perceptual equivalence as a function of complexity. Two unimodal experiments – vision and touch-only, and one crossmodal experiment investigating the availability of information across the senses, were performed. We find that, for the class of stimuli used, subjects were able to visually discriminate them reliably across the entire range of complexity, while the experiments involving haptic information show a marked decrease in performance as the objects become more complex. Performance in the crossmodal condition appears to be constrained by the limits of the subjects’ haptic representation, but the combination of the two sources of information is of some benefit over vision alone when comparing the simpler, low-frequency stimuli. This result shows that there is crossmodal transfer, and therefore perceptual equivalency, but that this transfer is limited by the object’s complexity.

Effects of Feedback Frequency and Timing on Acquisition, Retention, and Transfer of Speech Skills in Acquired Apraxia of Speech

Two studies examined speech skill learning in persons with apraxia of speech (AOS). Motor-learning research shows that delaying or reducing the frequency of feedback promotes retention and transfer of skills. By contrast, immediate or frequent feedback promotes temporary performance enhancement but interferes with retention and transfer. These principles were tested in the context of a common treatment for AOS. Two studies (N = 4, N = 2) employed single-subject treatment designs to examine acquisition and retention of speech skills in adults with AOS under different feedback conditions. Reduced-frequency or delayed feedback enhanced learning in 3 participants with AOS. Feedback manipulation was not an influential variable in 3 other cases in which stimulus-complexity effects may have masked treatment effects. These findings demonstrate that individuals with AOS can benefit from structured intervention. They provide qualified support for reduction and delay of feedback, although interaction with other factors such as stimulus complexity or task difficulty needs further exploration. This study adds to the growing body of literature investigating the use of principles of motor learning in treating AOS and provides impetus for consideration of pre-treatment variables that affect outcome in treatment studies.