Effects Of Stimulus Familiarity Research Articles

Interacting effects of stimulus familiarity, attention and language in the visual word form area

Interacting effects of stimulus familiarity, attention and language in the visual word form area

Identifying task-general effects of stimulus familiarity in the parietal memory network

Studies of human memory have implicated a “parietal memory network” in the recognition of familiar stimuli. However, the automatic vs. top-down nature of information processing within this network is not yet understood. If the network processes stimuli automatically, one can expect repetition-related changes both when familiarity is central to an ongoing task and when it is task-irrelevant. Here, we tested this prediction in a group of 40 human subjects using fMRI. Subjects initially named 100 objects aloud in the scanner. They then repeated the same task with novel and previously-named objects intermixed (where familiarity was not task-relevant) and separately were asked to make old/new recognition decisions in response to pictures of novel and previously-named objects (where familiarity was central to task completion). Accuracy was matched across conditions, and voice reaction times reflected typical behavioral priming effects. Repetition enhancement effects were restricted primarily to parietal cortex—and in particular, the parietal memory network—and were task-general in nature, whereas repetition suppression effects were task-dependent and occurred primarily in frontal and ventral temporal cortex. Task context effects were also present in the parietal memory network and impacted responses to both novel and familiar items. We conclude by discussing implications of these findings with respect to current hypotheses regarding parietal contributions to memory retrieval.

Item strength affects working memory capacity.

Do the processing and online manipulation of stimuli that are less familiar require more working memory (WM) resources? Is it more difficult to solve demanding problems when the symbols involved are less rather than more familiar? We explored these questions with a dual-task paradigm in which subjects had to solve algebra problems of different complexities while simultaneously holding novel symbol-digit associations in WM. The symbols were previously unknown Chinese characters, whose familiarity was manipulated by differential training frequency with a visual search task for nine hour-long sessions over 3 weeks. Subsequently, subjects solved equations that required one or two transformations. Before each trial, two different integers were assigned to two different Chinese characters of the same training frequency. Half of the time, those characters were present as variables in the equation and had to be substituted for the corresponding digits. After attempting to solve the equation, subjects had to recognize which two characters were shown immediately before that trial and to recall the integer associated with each. Solution accuracy and response times were better when the problems required one transformation only; variable substitution was not required; or the Chinese characters were high frequency. The effects of stimulus familiarity increased as the WM demands of the equation increased. Character-digit associations were also recalled less well with low-frequency characters. These results provide strong support that WM capacity depends not only on the number of chunks of information one is attempting to process but also on their strength or familiarity.

Differential Phonological and Semantic Modulation of Neurophysiological Responses to Visual Word Recognition

Background: Reading words for meaning relies on orthographic, phonological and semantic processing. The triangle model implicates a direct orthography-to-semantics pathway and a phonologically mediated orthography-to-semantics pathway, which interact with each other. The temporal evolution of processing in these routes is not well understood, although theoretical evidence predicts early phonological processing followed by interactive phonological and semantic processing. Method: This study used electroencephalography-event-related potential (ERP) analysis and magnetoencephalography (MEG) source localisation to identify temporal markers and the corresponding neural generators of these processes in early (∼200 ms) and late (∼400 ms) neurophysiological responses to visual words, pseudowords and consonant strings. Results: ERP showed an effect of phonology but not semantics in both time windows, although at ∼400 ms there was an effect of stimulus familiarity. Phonological processing at ~200 ms was localised to the left occipitotemporal cortex and the inferior frontal gyrus. At 400 ms, there was continued phonological processing in the inferior frontal gyrus and additional semantic processing in the anterior temporal cortex. There was also an area in the left temporoparietal junction which was implicated in both phonological and semantic processing. In ERP, the semantic response at ∼400 ms appeared to be masked by concurrent processes relating to familiarity, while MEG successfully differentiated these processes. Discussion: The results support the prediction of early phonological processing followed by an interaction of phonological and semantic processing during word recognition. Neuroanatomical loci of these processes are consistent with previous neuropsychological and functional magnetic resonance imaging studies. The results also have implications for the classical interpretation of N400-like responses as markers for semantic processing.

Electrodermal Response to Reward and Non‐Reward Among Children With Autism

Pervasive social difficulties among individuals with autism spectrum disorder (ASD) are often construed as deriving from reduced sensitivity to social stimuli. Behavioral and neurobiological evidence suggests that typical individuals show preferential processing of social (e.g., voices, faces) over nonsocial (e.g., nonvocal sounds, images of objects) information, whereas individuals with ASD may not. This reduction in sensitivity may reflect disrupted reward processing [Dawson & Bernier, ], with significant developmental consequences for affected individuals. In this study, we explore effects of social and monetary reward on behavioral and electrodermal responses (EDRs) among 8- to 12-year-old boys with (n = 18) and without (n = 18) ASD, with attention to the potential moderating effects of stimulus familiarity. During a simple matching task, participants with and without ASD had marginally slower reactions during social vs. nonsocial reward, and boys with ASD had less accurate responses than controls. Compared to baseline, reward and non-reward conditions elicited more frequent and larger EDRs for participants as a whole, and both groups showed similar patterns of EDR change within reward blocks. However, boys with and without ASD differed in their EDRs to non-reward, and response amplitude was correlated with social and emotional functioning. These findings provide some support for altered reward responding in ASD at the autonomic level, and highlight the discontinuation of reward as an important component of reward-based learning that may play a role in shaping behavior and guiding specialized brain development to subserve social behavior and cognition across the lifespan.

The effect of stimulus familiarity on the subsequent information processing: An ERP study

The effect of stimulus familiarity on the subsequent information processing: An ERP study

Both predictability and familiarity facilitate contour integration

Research has shown that contour detection is impaired in the visual periphery for snake-shaped Gabor contours but not for circular and elliptical contours. This discrepancy in findings could be due to differences in intrinsic shape properties, including shape closure and curvature variation, as well as to differences in stimulus predictability and familiarity. In a detection task using only circular contours, the target shape is both more familiar and more predictable to the observer compared with a detection task in which a different snake-shaped contour is presented on each trial. In this study, we investigated the effects of stimulus familiarity and predictability on contour integration by manipulating and disentangling the familiarity and predictability of snakelike stimuli. We manipulated stimulus familiarity by extensively training observers with one particular snake shape. Predictability was varied by alternating trial blocks with only a single target shape and trial blocks with multiple target shapes. Our results show that both predictability and familiarity facilitated contour integration, which constitutes novel behavioral evidence for the adaptivity of the contour integration mechanism in humans. If familiarity or predictability facilitated contour integration in the periphery specifically, this could explain the discrepant findings obtained with snake contours as compared with circles or ellipses. However, we found that their facilitatory effects did not differ between central and peripheral vision and thus cannot explain that particular discrepancy in the literature.

Strategies for longitudinal neuroimaging studies of overt language production

Longitudinal fMRI studies of language production are of interest for evaluating recovery from post-stroke aphasia, but numerous methodological issues remain unresolved, particularly regarding strategies for evaluating single subjects at multiple timepoints. To address these issues, we studied overt picture naming in eleven healthy subjects, scanned four times each at one-month intervals. To evaluate the natural variability present across repeated sessions, repeated scans were directly contrasted in a unified statistical framework on a per-voxel basis. The effect of stimulus familiarity was evaluated using explicitly overtrained pictures, novel pictures, and untrained pictures that were repeated across sessions. For untrained pictures, we found that activation declined across multiple sessions, equally for both novel and repeated stimuli. Thus, no repetition priming for individual stimuli at one-month intervals was found, but rather a general effect of task habituation was present. Using a set of overtrained pictures identical in each session, no decline was found, but activation was minimized and produced less consistent patterns across participants, as measured by intra-class correlation coefficients. Subtraction of a baseline task, in which subjects produced a stereotyped utterance to scrambled pictures, resulted in specific activations in the left inferior frontal gyrus and other language areas for untrained items, while overlearned stimuli relative to pseudo pictures activated only the fusiform gyrus and supplementary motor area. These findings indicate that longitudinal fMRI is an effective means of detecting changes in neural activation magnitude over time, as long as the effect of task habituation is taken into account.

Dissociating object familiarity from linguistic properties in mirror word reading

BackgroundIt is known that the orthographic properties of linguistic stimuli are processed within the left occipitotemporal cortex at about 150–200 ms. We recorded event-related potentials (ERPs) to words in standard or mirror orientation to investigate the role of visual word form in reading. Word inversion was performed to determine whether rotated words lose their linguistic properties.MethodsAbout 1300 Italian words and legal pseudo-words were presented to 18 right-handed Italian students engaged in a letter detection task. EEG was recorded from 128 scalp sites.ResultsERPs showed an early effect of word orientation at ~150 ms, with larger N1 amplitudes to rotated than to standard words. Low-resolution brain electromagnetic tomography (LORETA) revealed an increase in N1 to rotated words primarily in the right occipital lobe (BA 18), which may indicate an effect of stimulus familiarity. N1 was greater to target than to non-target letters at left lateral occipital sites, thus reflecting the first stage of orthographic processing. LORETA revealed a strong focus of activation for this effect in the left fusiform gyrus (BA 37), which is consistent with the so-called visual word form area (VWFA). Standard words (compared to pseudowords) elicited an enhancement of left occipito/temporal negativity at about 250–350 ms, followed by a larger anterior P3, a reduced frontal N400 and a huge late positivity. Lexical effects for rotated strings were delayed by about 100 ms at occipito/temporal sites, and were totally absent at later processing stages. This suggests the presence of implicit reading processes, which were pre-attentive and of perceptual nature for mirror strings.ConclusionThe contrast between inverted and standard words did not lead to the identification of a purely linguistic brain region. This finding suggests some caveats in the interpretation of the inversion effect in subtractive paradigms.

Repetition effects for words and nonwords as indexed by event-related fMRI: a preliminary study.

We have previously shown differential effects of stimulus familiarity on the repetition-related responses in right fusiform cortex to both faces and symbols. Repetition of familiar stimuli produced a response decrease, whereas repetition of unfamiliar stimuli produced a response increase. In the present experiment, we used words and nonwords as the familiar and unfamiliar stimuli respectively. In this case, the only fusiform region showing the familiarity-by-repetition interaction was in anterior left fusiform. This left-lateralisation of the fusiform interaction is consistent with our hypothesis that these repetition-related effects occur in the same regions responsible for perceptual recognition of familiar stimuli.

The Representation of Shape in the Context of Visual Object Categorization Tasks

To investigate the role of human fusiform gyrus in shape processing, we determined the effect of shape degradation on BOLD contrast in this region with fMRI during three tasks requiring subjects to determine either whether two successively presented nonsense shapes had the same global orientation (OR task); whether two successively presented meaningful objects belonged to the same basic level category (CAT task); or whether two successively presented objects represented the same exemplar of a category (EX task). On the behavioral level, shape degradation by locally shifting the pixels constituting the lines of stimuli had no effect on performance in the OR task, while it was detrimental to performance in the CAT and EX tasks. In comparison to the OR task, both the CAT and EX tasks were associated with activations in the occipitotemporal and parietal cortex. When shape degradation was applied, activation in the middle fusiform gyrus was reduced in all tasks. The occurrence of this effect in the OR task indicates that it is independent of memory representations. The persistence of the effect in both tasks that showed a behavioral effect of degradation suggests that it does not reflect the amount of shape processing performed on the stimuli, but rather the specificity of the final perceptual representation that can be built from the shape information that is available. Other studies have shown effects of stimulus familiarity and task requirements in the fusiform gyrus, suggesting that there is no need to assume different modules for perceptual representation and representation in memory.

Developmental differences in children's understanding of epistemic authority

An experiment was carried out to examine age differences in children's understanding of epistemic authority and its role in conversation. Two hundred and forty-six children from two age groups (6–7 and 11–12 years) were asked to make an independent judgement as to the equality or inequality of two lines in an optical illusion. Experimental conditions varied; ‘expertise’ in the task was given by training in a measurement algorithm and ‘familiarity with related stimuli’ by being shown illusions other than the test stimulus in training. Subjects who had answered independently that the lines were equal in length were paired with a same-age subject who had responded that they were unequal, and the two were then asked to arrive at agreement. Results showed that younger children rely on external features of a situation in justifying their beliefs. Gender differences in conversations suggest younger children have difficulty differentiating status and knowledge attributes of authority. Older children displayed an awareness of self as a necessarily autonomous element in the process of knowledge acquisition. Unexpected gender effects of stimulus familiarity in the process of persuasion are probably due to differences in subjects' behavioural styles.

The effect of stimulus familiarity on magnitude‐estimation scaling of different languages

The purpose of this study was to examine listener’s abilities to judge the subjective parameter of loudness of familiar and unfamiliar spoken languages. Two groups of subjects consisting of 20 adults each, ranging in age from 20–32 years, participated. Group 1 consisted of subjects who were familiar with English and not familiar with Hindi. Group 2 consisted of subjects who were familiar with English as well as Hindi. Two separate magnitude‐estimation scaling tasks were performed. For the first task, subjects in both groups were instructed to assign a numerical value that corresponded to the loudness of each of nine suprathreshold intensity levels of an English sentence. For the second task, subjects in both groups were instructed to assign a numerical value that corresponded to the loudness of each of nine suprathreshold intensity levels of the same sentence spoken in Hindi. Statistical analysis showed no significant difference between the two groups in the scaling of the English and Hindi sentences. Results suggested that magnitude‐estimation scaling appears to be an effective measure of loudness of familiar and unfamiliar languages, and that subjects scale the loudness of a familiar language the same way as they scale the loudness of an unfamiliar language.

Drawing Familiar or Unfamiliar Cards: Stimulus Familiarity, Chance Orientation, and the Illusion of Control

This study examined a condition under which the effect of stimulus familiarity on the illusion of control is suppressed. According to Langer, stimulus familiarity induces a skill orientation even in a chance situation. However, this effect is postulated to obtain only as long as the person's focus of attention remains on the stimulus familiarity. When the focus of attention turns toward the chance elements in the situation, the illusion of control should disappear Subjects participated in a wagering session with an experimenter by picking a card out of a shuffled pack. The cards either were normal looking (familiar cards) or had a striking "Egyptian" look (unfamiliar cards). As predicted, people wagered more money when playing with the familiar cards unless they had to evaluate their probability of winning before placing their bet.

Hippocampus and medial temporal cortex: Neuronal activity related to behavioural responses during the performance of memory tasks by primates

Neuronal activity was recorded in the hippocampal formation, the parahippocampal gyrus and medial inferotemporal cortex of monkeys performing memory tasks. In a modified delayed matching to sample task in which 2 sequentially presented stimuli were compared on each trial, a match condition required a right panel press, whereas a non-match condition required a left panel press. The activity of 336 736 (45.7%) neurons was related to the behavioural responses (left or right panel presses) in this task. The incidence of response-related activity was 57.4% in cortical areas adjacent to the rhinal sulcus plus medial inferotemporal cortex, and 40.2% for the hippocampal formation. For 58.9% of these response-related neurons, the activity change associated with the behavioural response was greater than that during presentation of the sensory stimuli, though neurons commonly responded (33.2% of all recorded neurons) to both sensory and motor events. The activity of 198 neurons (26.9%) differed between go-left and go-right trials; such neurons were found in all areas but were nearly twice as common in the posterior as in the anterior hippocampal formation. The importance of visual stimuli for the response-related neuronal activity was examined during the performance of a delayed alternation task without visual cues indicating direction of response. The response-related activity of 8 neurons recorded during the delayed alternation and the delayed matching tasks was similar in both tasks, indicating that memory for the behavioural responses influences the activity of the response-related neurons. In order to test the effects of stimulus familiarity and non-spatial responses on medial temporal neurons, recognition memory and visual discrimination tasks requiring lick responses were performed. The activity of 2 375 (0.5%) neurons was related to the lick responses; 3 68 neurons in the inferomedial temporal cortex responded on the basis of stimulus novelty and none reflected their reinforcement value. It is concluded that the hippocampal formation, the parahippocampal gyrus and medial inferotemporal cortex all have a role in the utilisation of sensory, mnemonic and motor information underlying the selection of spatially-directed behavioural responses.

Developmental Studies of Alertness and Encoding Effects of Stimulus Repetition

The findings reviewed here suggest a broadened view of the stimulus-familiarization effect as one of a general class of phenomena resulting from repetition-induced changes in the processes of alterness and encoding. Cantor's original observation of slowed responding to familiarized stimuli can be attributed on this account to experimental conditions under which the magnitude of alterness decrement is greater than encoding facilitation. Exactly the opposite result can be obtained by arranging conditions so as to highlight the encoding facilitation effect relative to the alterness decrement effect. For example, faster responding to familiarized stimuli has been found under conditions in which (1) the imperative stimulus is preceded by a neutral warning signal or, (2) a delay is imposed between the familiarization and the test phases. Earlier, it was noted that the experimental technique of repeated stimulus presentation is widely used in the study of infant perception, with little concern for the mechanisms responsible for what is generically referred to as habituation. Posner and Rothbart (1980) made a similar observation and suggested, on the basis of Kraut's (1976) results, that Habituation in the infant can be viewed as a reduction in the flow of information from the recognition pathway [encoding] into the alerting system. Input is still processed along the recognition pathway, but its failure to activate the alerting system reduces the availability of the central processor and hence of nonhabitual responses. We have developed a model of attention that accounts for our findings and embodies Posner and Rothbart's general idea. It suggests that both the alertness and the encoding functions must reach separate threshold levels for a correct recognition response. The time required to get to each threshold level is changed as a function of stimulus repetition. Repetition slows alertness "rise time," but it speeds encoding "rise time." In comparing the responses to a familiarized color versus those to a novel color, the model can be seen in Fig. 1a. Because any response must await an appropriate level of alertness, the familiarized stimulus is responded to more slowly than the novel one, even though encoding rise time to the familiarized stimulus if fast. Either a delay between familiarization and test or a warning signal acts to mitigate the effects of familiarization on alertness. Alertness rise time for the familiarized stimulus is similar to that for the novel stimulus, but encoding rise time for the familiarized stimulus is faster than for the novel.(ABSTRACT TRUNCATED AT 400 WORDS)

Word identification in reading proceeds from spelling to sound to meaning.

Van Orden (1987) reported that false positive errors in a categorization task are elevated for homophonic foils (e.g., HARE for A PART OF THE HUMAN BODY). Two new experiments replicate this finding and extend it to nonword homophone foils (e.g., SUTE FOR AN ARTICLE OF CLOTHING). False positive errors to nonword homophone foils substantially exceed false positive errors to nonhomophonic nonword spelling controls, showing that the phonological characteristics of the nonword foils are critical. Because nonwords are not represented in the lexicon, this new result implicates computed phonological codes as a source of the categorization errors. Additionally, in each of two experiments, matched word and nonword homophones produced virtually identical error rates. If stimulus nonword homophones are viewed as extremely unfamiliar words, compared with the relatively familiar stimulus word homophones, then our failure to observe an effect of stimulus familiarity strengthens the case that phonological coding plays a role in the identification of all printed words. The fact that the results are obtained in a categorization task that requires reading for meaning (rather than a lexical decision task) makes it difficult to avoid the conclusion that phonological mediation plays a role in normal reading of text for meaning.

Effects of two types of familiarity on children's referential communication abilities

Stimulus familiarity has been shown to facilitate children's performance on referential communication tasks. The facilitative effects of stimulus familiarity could result either from prior stimulus recognizability or from immediate experience with experimental stimuli. The present study separated the effects of stimulus recognizability and experience. Kindergarten and third grade children communicated about both familiar and novel stimuli. Half the children were exposed to both types of stimuli prior to participation. The results indicated that older children chose the correct referent more often than younger children; children who received experience performed better than children who did not, and familiar stimuli were described more accurately than novel stimuli. The effects of stimulus recognizability and experience were independent. Third‐grade listeners were more likely to ask for additional information than kindergarten listeners, and third‐grade speakers tended to respond to such requests more often by providing new information. Results were discussed in terms of the independence of stimulus recognizability and experimental experience.

The effect of stimulus familiarity on the use of criteria and justifications in children's social reasoning

Early studies of moral judgement described young children's thought as undifferentiated and oriented toward external features of transgressions. However, more recent evidence suggests that young children distinguish between domains of social transgression and justify moral judgements with reference to the transgression itself, rather than to external features such as rules, authority directives, or sanctions. The present study hypothesized a possible explanation for this discrepancy: that undifferentiated reasoning occurs with the use of unfamiliar stimulus events or stimulus events not clearly differentiated with respect to social domain. Sixty‐one 6‐, 8‐, and 10‐year‐olds were interviewed about four types of social transgression: familiar moral, unfamiliar moral, familiar conventional, and unfamiliar conventional. Assessments were made of several dimensions of judgement hypothesized to be criterial for the differentiation of social domains; responses were also analysed for types of justification used. For familiar stimuli all age groups showed a differentiated understanding of moral and conventional issues, both in judgement and in justification. Younger subjects showed less differentiation in judgement than older subjects when stimuli were unfamiliar. Age differences were also found in the types of justification given, both for familiar and for unfamiliar moral issues. The findings indicate that stimulus familiarity is a more significant factor in the moral reasoning of younger than of older children.

Effect of familiarity of Multielement matching.

The effect of stimulus familiarity on physical matching was examined in three experiments. In Experiment 1, subjects matched English and Armenian letters. String length varied from one to three items. Familiarity had no effect when two single items were compared, but it had increasingly marked effects with two- and three-item strings. The pattern of same/different responses and serial position effects implicated the comparison process for three-item matches. Experiment 2 varied stimulus onset asynchrony to assess the contribution of familiarity to speeding up encoding and/or to maintaining a representation in memory; only two-item strings were used. Encoding Armenian letters required more time than encoding English, but there was no additional decrement due to holding the representation in memory. In Experiment 3, one group of subject learned names for the Armenian letters and another group practiced drawing the letters. The availability of names did not decrease the familiarity effect. These data suggest that familiarity invariably has a strong effect on the encoding process and influences comparison processes when task requirements are sufficiently demanding.