Same-different Task Research Articles

How well can young adults and children discriminate between odors?

It is widely believed that people can distinguish between many odors although there is limited empirical evidence. Odor discrimination tasks are employed much less often than other measures of olfaction, but, interestingly, performance is typically ~ 75% correct. This less-than-perfect performance is rarely highlighted, although it suggests that people may not be as good at discriminating odors as is commonly believed. Odor discrimination is understudied in children, and although available evidence suggests that it improves with age, children perform better when the task is simpler. In the present study, we explored odor discrimination in children and young adults with a relatively simple same-different task using common and uncommon odors. We found that children perform as well as young adults, but that overall performance was less than perfect and depended on the odors to be discriminated. We found evidence that ability to discriminate between odors improves as the difference in pleasantness of the odors increases. In a second experiment, we tested this directly by exploring whether odors that differ in pleasantness and edibility, two dimensions that appear to be important in olfactory perception, are easier to discriminate than odors that are the same on those dimensions. We found further evidence that odors that differ in pleasantness are easier to discriminate.

Unconscious Integration of Categorical Relationship of Two Subliminal Numbers in Comparison with "5".

Many studies have shown that the brain can process subliminal numerals, i.e., participants can categorize a subliminal number into two categories: greater than 5 or less than 5. In the context of many studies on the unconscious integration of multiple subliminal stimuli, the issue of whether multiple subliminal numbers can be integrated is contentious. The same-different task is regarded as a perfect tool to explore unconscious integration. In the two experiments reported, we used a same-different task in which a pair of masked prime numbers was followed by a pair of target numbers, and participants were asked to decide whether the two target numbers were on the same (both smaller or larger than 5) or different sides (one smaller, the other larger than 5) of 5 in magnitude. The results indicated that the prime numbers could be categorized unconsciously, which was reflected by the category priming effect, and that the unconscious category relationship of the two prime numbers could affect the judgment on the category relationship of the two target numbers, as reflected by the response priming effect. The duration of the prime-to-target interstimulus interval (ISI) was also manipulated, showing a positive compatibility effect (PCE) of category priming and a negative compatibility effect (NCE) of response priming no matter whether the ISI was short (50 ms) or long (150 ms). The NCE, which occurred when the prime-to-target ISI was relatively short in this study, contradicted the conventional view but was consistent with previous results of unconscious integration based on an attention modulation mechanism. Importantly, this study provided evidence for the still-under-debate issue of numerical information integration.

Sources and goals in memory and language: Fragility and robustness in event representation

Previous research has demonstrated an asymmetry between Sources and Goals in people’s linguistic and non-linguistic encoding of motion events: when describing events such as a fairy going from a tree to a flower, people mention the Goal (“to a flower”) more often than the Source (“from a tree”); similarly, people are better at detecting Goal than Source changes in memory tests. However, all prior work used a single task to probe memory of Sources and Goals and thus left the nature of the fragility of event components open. Here, we probed memory for Sources and Goals using either a Same-different or a Forced-choice task after participants passively viewed (Experiment 1), viewed and described (Experiment 2) or viewed and heard descriptions of (Experiment 3) the same set of motion events. We robustly replicated the linguistic Source-Goal asymmetry. However, across encoding contexts, the memory asymmetry persisted in the Same-different task but disappeared in the Forced-choice task. The Same-different task results did not change even when participants were explicitly asked to attend to Sources (Experiment 4a) and when motion trajectory was removed at test (Experiment 4b), ruling out a purely test-expectation account for the cross-task effect. We conclude that Sources of motion, even when not mentioned in language nor successfully retrieved at memory test, are nevertheless represented as part of a motion event, and their detailed representation can be reinstated at aided retrieval contexts. Our data clarify the nature of event representation and suggest a fine-grained homology between language and event memory.

The psychophysics of human three-dimensional active visuospatial problem-solving

Our understanding of how visual systems detect, analyze and interpret visual stimuli has advanced greatly. However, the visual systems of all animals do much more; they enable visual behaviours. How well the visual system performs while interacting with the visual environment and how vision is used in the real world is far from fully understood, especially in humans. It has been suggested that comparison is the most primitive of psychophysical tasks. Thus, as a probe into these active visual behaviours, we use a same-different task: Are two physical 3D objects visually the same? This task is a fundamental cognitive ability. We pose this question to human subjects who are free to move about and examine two real objects in a physical 3D space. The experimental design is such that all behaviours are directed to viewpoint change. Without any training, our participants achieved a mean accuracy of 93.82%. No learning effect was observed on accuracy after many trials, but some effect was seen for response time, number of fixations and extent of head movement. Our probe task, even though easily executed at high-performance levels, uncovered a surprising variety of complex strategies for viewpoint control, suggesting that solutions were developed dynamically and deployed in a seemingly directed hypothesize-and-test manner tailored to the specific task. Subjects need not acquire task-specific knowledge; instead, they formulate effective solutions right from the outset, and as they engage in a series of attempts, those solutions progressively refine, becoming more efficient without compromising accuracy.

Analyses of response time data in the same–different task.

The Same-Different task presents two stimuli in close succession and participants must indicate whether they are completely identical or if there are any attributes that differ. While the task is simple, its results have proven difficult to explain. Notably, response times are characterized by a fast-same effect whereby Same responses are faster than Different responses even though identical stimuli should be exhaustively processed to be accurate. Herein, we examine a little more than a quarter million response times (N = 255,744) obtained from 327 participants who participated in one of 14 variants of the task involving minor changes in the stimuli or their durations. We performed distribution fitting and analyzed estimated parameters stemming from the ex-Gaussian, lognormal, and Weibull distributions to infer the cognitive processing characteristics underlying this task. The results exclude serial processing of the stimuli and do not support dual-route processing. The fast-same effect appears only through a shift of the entire response time distributions, a feature impossible to detect solely with mean response time analyses. An attention-modulated process driven by entropy may be the most adequate model of the fast-same effect. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Priming effects in reading words with vertically and horizontally mirrored letters.

We conducted two masked priming experiments to examine how the orthographic system processes words with mirrored letters. In both experiments, four different primes were used: an identity prime, an unrelated control prime, and two mirror-primes in which letters were either mirrored at their vertical or horizontal axis. Task was varied between experiments: In Experiment 1, we used a lexical decision task, and in Experiment 2, we used a cross-case same-different match task. We expected to see priming effects in both mirror-conditions with stronger effects in the vertically than in the horizontally mirrored letters. In the lexical decision task, we observed only vertical priming effects for words, whereas in the same-different task, priming effects were present in both mirror-conditions and for both words and non-words. We discuss the implications of our findings for extant models of orthographic processing.

How do irrelevant stimuli from another modality influence responses to the targets in a same-different task

It remains unclear whether multisensory interaction can implicitly occur at the abstract level. To address this issue, a same-different task was used to select comparable images and sounds in Experiment 1. Then, the stimuli with various levels of discrimination difficulty were adopted in a modified same-different task in Experiments 2, 3, and 4. The resultsshowed that only when the irrelevant stimuli were easily distinguishable, aconsistency effectcould beobservedin the testing phase. Moreover, when easily distinguishableirrelevant stimuliwere simultaneously presented with difficulttarget stimuli, irrelevant auditorystimuli facilitated responses to visual targets whereas irrelevant visual stimuli interfered with responses to auditorytargetsin the training phase,indicating an asymmetry in the role of visual and auditory in abstract multisensory integration. The results suggested that abstract multisensory information could be implicitly integrated and the inverse effectiveness principle might not apply to high-level processing of abstract multisensory integration.

Can deep convolutional neural networks support relational reasoning in the same-different task?

Same-different visual reasoning is a basic skill central to abstract combinatorial thought. This fact has lead neural networks researchers to test same-different classification on deep convolutional neural networks (DCNNs), which has resulted in a controversy regarding whether this skill is within the capacity of these models. However, most tests of same-different classification rely on testing on images that come from the same pixel-level distribution as the training images, yielding the results inconclusive. In this study, we tested relational same-different reasoning in DCNNs. In a series of simulations we show that models based on the ResNet architecture are capable of visual same-different classification, but only when the test images are similar to the training images at the pixel level. In contrast, when there is a shift in the testing distribution that does not change the relation between the objects in the image, the performance of DCNNs decreases substantially. This finding is true even when the DCNNs’ training regime is expanded to include images taken from a wide range of different pixel-level distributions or when the model is trained on the testing distribution but on a different task in a multitask learning context. Furthermore, we show that the relation network, a deep learning architecture specifically designed to tackle visual relational reasoning problems, suffers the same kind of limitations. Overall, the results of this study suggest that learning same-different relations is beyond the scope of current DCNNs.

Where is mirror invariance? Masked priming effects by mirrored and rotated transformations of reversible and nonreversible letters

The cognitive mechanism underpinning mirror priming effects for letters (e.g., IDEA primed by ibea) is still unclear: it could be about mirror invariance (perceptual equivalence of mirror images - d and b - which does not extend to other orientation contrasts like plane rotations - d and p) or about visual similarity (b, d, and p share the same visual features and shape). To enlighten it and investigate the modulatory role of task and orthographic context (words vs single letters), we manipulated letter (nonreversible; reversible) and prime condition (identity, mirrored, rotated, control) in four masked priming experiments: lexical decision with conventional and sandwich paradigms (Experiments 1 and 2), same-different task on words and single letters (Experiments 3 and 4). All experiments replicated the differential mirror priming effect: inhibitory for reversible letters, facilitatory for nonreversible letters. Notably, similar priming effects were found for plane rotations. Regardless of task or orthographic context, a reliably larger orientation cost was found for reversible than nonreversible letters for both mirror images and plane rotations. These results suggest that the underlying mechanism is not mirror invariance, but rather visual similarity allied with prelexical dynamics.

Spatial Alignment Facilitates Visual Comparison in Children

Visual comparison is a key process in everyday learning and reasoning. Recent research has discovered the spatial alignment principle, based on the broader framework of structure‐mapping theory in comparison. According to the spatial alignment principle, visual comparison is more efficient when the figures being compared are arranged in direct placement—that is, juxtaposed with parallel structural axes. In this placement, (1) the intended relational correspondences are readily apparent, and (2) the influence of potential competing correspondences is minimized. There is evidence for the spatial alignment principle in adults’ visual comparison (Matlen et al., 2020). Here, we test whether it holds for children. Six‐ and eight‐year‐old children performed a same‐different task over visual pairs. The results indicated that direct placement led to faster and more accurate comparison, both for concrete same‐different matches (matches of both objects and relations) and for purely relational matches—evidence that the same structural alignment process holds for visual comparison in 6‐ and 8‐year‐olds as in adults. These findings have implications for learning and education.

Paper wasps form abstract concept of 'same and different'.

Concept formation requires animals to learn and use abstract rules that transcend the characteristics of specific stimuli. Abstract concepts are often associated with high levels of cognitive sophistication, so there has been much interest in which species can form and use concepts. A key abstract concept is that of sameness and difference, where stimuli are classified as either the same as or different than an original stimulus. Here, we used a simultaneous two-item same-different task to test whether paper wasps (Polistes fuscatus) can learn and apply a same-different concept. We trained wasps by simultaneously presenting pairs of same or different stimuli (e.g. colours). Then, we tested whether wasps could apply the concept to new stimuli of the same type (e.g. new colours) and to new stimulus types (e.g. odours). We show that wasps learned a general concept of sameness or difference and applied it to new samples and types of stimuli. Notably, wasps were able to transfer the learned rules to new stimuli in a different sensory modality. Therefore, P. fuscatus can classify stimuli based on their relationships and apply abstract concepts to novel stimulus types. These results indicate that abstract concept learning may be more widespread than previously thought.

Speaker discrimination as a function of vowel realization: does focus affect perception?

The acoustic-phonetic characteristics of speech sounds are influenced by their linguistic position in the syllable or sentence. Because of acoustic-phonetic differences between different speech sounds, sounds vary in the amount of speaker information they contain. However, do spectral and durational differences between realizations of the same sound that were sampled from different linguistic positions also impact speaker information? We investigated speaker discrimination in [−focus] versus [+focus] word realizations. Twenty-one Dutch listeners participated in a same-different task, using stimuli varying in focus, vowel ([aː], [u]), and word context ([ɦ_k], [v_t]), spoken by 11 different speakers. Results showed that an effect of focus on speaker-dependent information was present, but limited to words containing [u]. Moreover, performance on [u] words was influenced by (interactions of) word context and trial type (same-vs. different-speaker). Context-dependent changes in a speech sound’s acoustics may affect its speaker-dependent information, albeit under specific conditions only.

Is the fast-same phenomenon that fast? An investigation of identity priming in the same-different task.

The same-different task is a classic paradigm that requires participants to judge whether two successively presented stimuli are the same or different. While this task is simple, with results that have been replicated many times, response times (RTs) and accuracy for both same and different decisions remain difficult to model. The biggest obstacle in modeling the task lies within its effect referred to as the fast-same phenomenon whereby participants are much faster at responding "same" than "different," while most standard cognitive models predict the opposite. In this study, we investigated whether this effect is the result of identity priming activated by the first stimulus. We ran four variants of the same-different task in which identity priming is intended to be attenuated or cancelled in half of the trials. Results for all four variants show that a complete visual match between both stimuli is necessary to observe a fast-same effect and that hampering this relation attenuates same RTs while different RTs remained relatively unchanged. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Elucidating the Common Basis for Task-Dependent Differential Manifestations of Category Advantage: A Decision Theoretic Approach.

Cross-category hues are differentiated easier than otherwise equidistant hues that belong to the same linguistic category. This effect is typically manifested through both accuracy and response time gains in tasks with a memory component, whereas only response times are affected when there is no memory component. This raises the question of whether there is a common generative process underlying the differential behavioral manifestations of category advantage in color perception. For instance, within the framework of noisy evidence accumulation models, changes in accuracy can be readily attributed to an increase in the efficacy of perceptual evidence integration (after controlling for threshold setting), whereas changes in response time can also be attributed to shorter nondecisional delays (e.g., due to facilitated signal detection). To address the latent decision processes underlying category advantage across different behavioral demands, we introduce a decision-theoretic perspective (i.e., diffusion decision model) to categorical color perception in three complementary experiments. In Experiment 1, we collected data from a binary color naming task (1) to determine the green-blue boundary in our sample and (2) to trace how parameter estimates of interest in the model output change as a function of color typicality. In Experiments 2 and 3, we used same-different task paradigms (with and without a memory component, respectively) and traced the category advantage in color discrimination in two parameters of the diffusion decision model: nondecision time and drift rate. An increase in drift rate predominantly characterized the category advantage in both tasks. Our results show that improved efficiency in perceptual evidence integration is a common driving force behind different manifestations of category advantage.

Repeated letters increase the ambiguity of strings: Evidence from identification, priming and same-different tasks

Letters are often repeated in words in many languages. The present work explored the mechanisms underlying processing of repeated and unique letters in strings across three experimental paradigms. In a 2AFC perceptual identification task, the insertion but not the deletion of a letter was harder to detect when it was repeated than when it was unique (Exp. 1). In a masked primed same-different task, deletion primes produced the same priming effect regardless of deletion type (repeated, unique; Exp. 2), but insertion primes were more effective when the additional inserted letter created a repetition than when it did not (Exp. 3). In a same-different perceptual identification task, foils created by modifying a repetition, by either repeating the wrong letter or substituting a repeated letter, were harder to reject than foils created by modifying unique letters (Exp. 4). Thus, repetition effects were task-dependent. Since considering representations alone would suggest repetition effects would always occur or never occur, this indicates the importance of modelling task-specific processes. The similarity calculations embedded in the Overlap Model (Gomez et al., 2008) appeared to always predict a repetition effect, but its decision rule for the task of Experiment 1 allowed it to predict the asymmetry between insertions and deletions. In the Letters in Time and Retinotopic Space (LTRS; Adelman, 2011) model, repetition effects arise only from briefly presented stimuli as their perception is incomplete. It was therefore consistent with Experiments 2–4 but required a task-specific response bias to account for the insertion-deletion asymmetry of Experiment 1.

A naturalistic environment to study visual cognition in unrestrained monkeys.

Macaque monkeys are widely used to study vision. In the traditional approach, monkeys are brought into a lab to perform visual tasks while they are restrained to obtain stable eye tracking and neural recordings. Here, we describe a novel environment to study visual cognition in a more natural setting as well as other natural and social behaviors. We designed a naturalistic environment with an integrated touchscreen workstation that enables high-quality eye tracking in unrestrained monkeys. We used this environment to train monkeys on a challenging same-different task. We also show that this environment can reveal interesting novel social behaviors. As proof of concept, we show that two naive monkeys were able to learn this complex task through a combination of socially observing trained monkeys and solo trial-and-error. We propose that such naturalistic environments can be used to rigorously study visual cognition as well as other natural and social behaviors in freely moving monkeys.

ERP Correlates of Altered Orthographic-Phonological Processing in Dyslexia.

Automatic visual word recognition requires not only well-established phonological and orthographic representations but also efficient audio-visual integration of these representations. One possibility is that in developmental dyslexia, inefficient orthographic processing might underlie poor reading. Alternatively, reading deficit could be due to inefficient phonological processing or inefficient integration of orthographic and phonological information. In this event-related potential study, participants with dyslexia (N = 25) and control readers (N = 27) were presented with pairs of words and pseudowords in an implicit same-different task. The reference-target pairs could be identical, or different in the identity or the position of the letters. To test the orthographic-phonological processing, target stimuli were presented in visual-only and audiovisual conditions. Participants with and without dyslexia processed the reference stimuli similarly; however, group differences emerged in the processing of target stimuli, especially in the audiovisual condition where control readers showed greater N1 responses for words than for pseudowords, but readers with dyslexia did not show such difference. Moreover, after 300 ms lexicality effect exhibited a more focused frontal topographic distribution in readers with dyslexia. Our results suggest that in developmental dyslexia, phonological processing and audiovisual processing deficits are more pronounced than orthographic processing deficits.

Which Factors Modulate Letter Position Coding in Pre-literate Children?

One of the central landmarks of learning to read is the emergence of orthographic processing (i.e., the encoding of letter identity and letter order): it constitutes the necessary link between the low-level stages of visual processing and the higher-level processing of words. Regarding the processing of letter position, many experiments have shown worse performance in various tasks for the transposed-letter pair judge-JUDGE than for the orthographic control jupte-JUDGE. Importantly, 4-y.o. pre-literate children also show letter transposition effects in a same-different task: TZ-ZT is more error-prone than TZ-PH. Here, we examined whether this effect with pre-literate children is related to the cognitive and linguistic skills required to learn to read. Specifically, we examined the relation of the transposed-letter in a same-different task with the scores of these children in phonological, alphabetic and metalinguistic awareness, linguistic skills, and basic cognitive processes. To that end, we used a standardized battery to assess the abilities related with early reading acquisition. Results showed that the size of the transposed-letter effect in pre-literate children was strongly associated with the sub-test on basic cognitive processes (i.e., memory and perception) but not with the other sub-tests. Importantly, identifying children who may need a pre-literacy intervention is crucial to minimize eventual reading difficulties. We discuss how this marker can be used as a tool to anticipate reading difficulties in beginning readers.

Deciphering human decision rules in motion discrimination

We investigated the eight decision rules for a same-different task, as summarized in Petrov (Psychonomic Bulletin & Review, 16(6), 1011–1025, 2009). These rules, including the differencing (DF) rule and the optimal independence rule, are all based on the standard model in signal detection theory. Each rule receives two stimulus values as inputs and uses one or two decision criteria. We proved that the false alarm rate p(F) ≤ 1/2 for four of the rules. We also conducted a same-different rating experiment on motion discrimination (n = 54), with 4∘ or 8∘ directional difference. We found that the human receiver operating characteristic (ROC) spanned its full range [0,1] in p(F), thus rejecting these four rules. The slope of the human Z-ROC was also < 1, further confirming that the independence rule was not used. We subsequently fitted in the four-dimensional (pAA, pAB, pBA, pBB) space the human data to the remaining four rules—DF and likelihood ratio rules, each with one or two criteria, where pXY = p(responding “different” given stimulus sequence XY). We found that, using residual distribution analysis, only the two criteria DF rule (DF2) could account for the human data.

Dysnumeria in Sign Language: Impaired Construction of the Decimal Structure in Reading Multidigit Numbers in a Deaf ISL Signer.

We report on the first in-depth analysis of a specific type of dysnumeria, number-reading deficit, in sign language. The participant, Nomi, is a 45-year-old signer of Israeli Sign Language (ISL). In reading multidigit numbers (reading-then-signing written numbers, the counterpart of reading aloud in spoken language), Nomi made mainly decimal, number-structure errors– reading the correct digits in an incorrect (smaller) decimal class, mainly in longer numbers of 5–6-digits. A unique property of ISL allowed us to rule out the numeric-visual analysis as the source of Nomi's dysnumeria: In ISL, when the multidigit number signifies the number of objects, it is signed with a decimal structure, which is marked morphologically (e.g., 84 → Eight-Tens Four); but a parallel system exists (e.g., for height, age, bus numbers), in which multidigit numbers are signed non-decimally, as a sequence of number-signs (e.g., 84 → Eight, Four). When Nomi read and signed the exact same numbers, but this time non-decimally, she performed significantly better. Additional tests supported the conclusion that her early numeric-visual abilities are intact: she showed flawless detection of differences in length, digit-order, or identity in same-different tasks. Her decimal errors did not result from a number-structure deficit in the phonological-sign output either (no decimal errors in repeating the same numbers, nor in signing multidigit numbers written as Hebrew words). Nomi had similar errors of conversion to the decimal structure in number comprehension (number-size comparison tasks), suggesting that her deficit is in a component shared by reading and comprehension. We also compared Nomi's number reading to her reading and signing of 406 Hebrew words. Nomi's word reading was in the high range of the normal performance of hearing controls and of deaf signers and significantly better than her multidigit number reading, demonstrating a dissociation between number reading, which was impaired, and word reading, which was spared. These results point to a specific type of dysnumeria in the number-frame generation for written multidigit numbers, whereby the conversion from written multidigit numbers to the abstract decimal structure is impaired, affecting both reading and comprehension. The results support abstract, non-verbal decimal structure generation that is shared by reading and comprehension, and also suggest the existence of a non-decimal number-reading route.