1,720,995 research outputs found
Unconventionally trendy: The pluralistic endeavour of Cortex into the human cognitive neurosciences
No full textThis viewpoint summarizes conversations between three generations of cognitive neuropsychologists about Cortex's contributions to our understanding of human cognition. We structured our conversation along a historical timeline and focused on selected key topics, that we also contributed to. Beginning with the advent of neuropsychology, and its focus on language disorders and hemispheric lateralisation, we quickly moved to the birth of Cortex in the 1960s pausing our conversion on spatial cognition and the critical window offered by unilateral neglect on its representational understanding. Realising that as time went by, the initial focus on impaired cognition expanded towards healthy individuals too, we noticed it coincided with the emergence of sophisticated imaging methods, and with them, the possibility to better draw the functional architecture of the brain across all known cognitive domains. In parallel, research on neuropsychological disorders had to include those implied by ageing, which rapidly became a critical topic due to the impressive increase of older individuals in Western societies. With the massive availability of data and shared information in the last decades, we observed a rise in open science practices and identified a clear future, yet to be fully unclosed, for a re-definition of neuropsychological profiles through big data in what is labelled as precision psychology. Across this journey, Cortex stood up for its unconventionally trendy, pluralistic and unbiased approach, which we hope will continue to be faithful to those core elements that are necessary to explain human cognition, which is, undoubtedly, among the most complex scientific subjects to tackl
The upside of cumulative conceptual interference on exemplar-level mnemonic discrimination.
Full text linkpeer reviewedAlthough long-term visual memory (LTVM) has a remarkable capacity, the fidelity of its episodic representations can be influenced by at least two intertwined interference mechanisms during the encoding of objects belonging to the same category: the capacity to hold similar episodic traces (e.g., different birds) and the conceptual similarity of the encoded traces (e.g., a sparrow shares more features with a robin than with a penguin). The precision of episodic traces can be tested by having participants discriminate lures (unseen objects) from targets (seen objects) representing different exemplars of the same concept (e.g., two visually similar penguins), which generates interference at retrieval that can be solved if efficient pattern separation happened during encoding. The present study examines the impact of within-category encoding interference on the fidelity of mnemonic object representations, by manipulating an index of cumulative conceptual interference that represents the concurrent impact of capacity and similarity. The precision of mnemonic discrimination was further assessed by measuring the impact of visual similarity between targets and lures in a recognition task. Our results show a significant decrement in the correct identification of targets for increasing interference. Correct rejections of lures were also negatively impacted by cumulative interference as well as by the visual similarity with the target. Most interestingly though, mnemonic discrimination for targets presented with a visually similar lure was more difficult when objects were encoded under lower, not higher, interference. These findings counter a simply additive impact of interference on the fidelity of object representations providing a finer-grained, multi-factorial, understanding of interference in LTVM
Age-related differences during visual search: the role of contextual expectations and cognitive control mechanisms
No full textDuring the visual search, cognitive control mechanisms activate to inhibit distracting information and efficiently orient attention
towards contextually relevant regions likely to contain the search target. Cognitive ageing is known to hinder cognitive control
mechanisms, however little is known about their interplay with contextual expectations, and their role in visual search. In two eyetracking experiments, we compared the performance of a younger and an older group of participants searching for a target object varying in semantic consistency with the search scene (e.g., a basket of bread vs. a clothes iron in a restaurant scene) after
being primed with contextual information either congruent or incongruent with it (e.g., a restaurant vs. a bathroom). Primes were administered either as scenes (Experiment 1) or words (Experiment 2, which included scrambled words as neutral primes). Participants also completed two inhibition tasks (Stroop and Flanker) to assess their cognitive control. Older adults had greater difficulty than younger adults when searching for inconsistent objects, especially when primed with congruent information (Experiment 1), or a scrambled word (neutral condition, Experiment 2). When the target object violates the semantics of the search context, congruent expectations or perceptual distractors, have to be suppressed through cognitive control, as they are irrelevant to the search. In fact, higher cognitive control, especially in older participants, was associated with better target detection in these more challenging conditions, although it did not influence eye-movement responses. These results shed new light on the links between cognitive control, contextual expectations and visual attention in healthy ageing
Differential effects of intrinsic properties of natural scenes and interference mechanisms on recognition processes in long-term visual memory
No full textHumans display remarkable long-term visual memory (LTVM) processes. Even though images may be intrinsically memorable, the fidelity of their visual representations, and consequently the likelihood of successfully retrieving them, hinges on their similarity when concurrently held in LTVM. In this debate, it is still unclear whether intrinsic features of images (perceptual and semantic) may be mediated by mechanisms of interference generated at encoding, or during retrieval, and how these factors impinge on recognition processes. In the current study, participants (32) studied a stream of 120 natural scenes from 8 semantic categories, which varied in frequencies (4, 8, 16 or 32 exemplars per category) to generate different levels of category interference, in preparation for a recognition test. Then they were asked to indicate which of two images, presented side by side (i.e. two-alternative forced-choice), they remembered. The two images belonged to the same semantic category but varied in their perceptual similarity (similar or dissimilar). Participants also expressed their confidence (sure/not sure) about their recognition response, enabling us to tap into their metacognitive efficacy (meta-d'). Additionally, we extracted the activation of perceptual and semantic features in images (i.e. their informational richness) through deep neural network modelling and examined their impact on recognition processes. Corroborating previous literature, we found that category interference and perceptual similarity negatively impact recognition processes, as well as response times and metacognitive efficacy. Moreover, images semantically rich were less likely remembered, an effect that trumped a positive memorability boost coming from perceptual information. Critically, we did not observe any significant interaction between intrinsic features of images and interference generated either at encoding or during retrieval. All in all, our study calls for a more integrative understanding of the representational dynamics during encoding and recognition enabling us to form, maintain and access visual information
Similar mechanisms of temporary bindings for identity and location of objects in healthy ageing: An eye-tracking study with naturalistic scenes
No full textThe ability to maintain visual working memory (VWM) associations about the identity and location
of objects has at times been found to decrease with age. To date, however, this age-related difficulty
was mostly observed in artificial visual contexts (e.g., object arrays), and so it is unclear whether it
may manifest in naturalistic contexts, and in which ways. In this eye-tracking study, 26 younger and
24 healthy older adults were asked to detect changes in a critical object situated in a photographic
scene (192 in total), about its identity (the object becomes a different object but maintains the same
position), location (the object only changes position) or both (the object changes in location and
identity). Aging was associated with a lower change detection performance. A change in identity was
harder to detect than a location change, and performance was best when both features changed,
especially in younger adults. Eye movements displayed minor differences between age groups (e.g.,
shorter saccades in older adults) but were similarly modulated by the type of change. Latencies to the
first fixation were longer and the amplitude of incoming saccades was larger when the critical object
changed in location. Once fixated, the target object was inspected for longer when it only changed
in identity compared to location. Visually salient objects were fixated earlier, but saliency did not
affect any other eye movement measures considered, nor did it interact with the type of change.
Our findings suggest that even though aging results in lower performance, it does not selectively
disrupt temporary bindings of object identity, location, or their association in VWM, and highlight
the importance of using naturalistic contexts to discriminate the cognitive processes that undergo
detriment from those that are instead spared by aging
Typicality in the brain during semantic and episodic memory decisions
Full text linkTypicality is a key semantic dimension supporting the categorical organization of items based on their features. Typical items share more features with other members of their category than atypical items, which are more distinctive. Typicality influences episodic recollection. Yet, the neural substrates of this effect have never been studied. This fMRI study investigated the neural correlates of typicality during semantic and episodic memory decisions . 26 subjects performed a categorization task on typical and atypical word concept and completed a recognition memory task. During the correct recognition of old items, regions from the core recollection network were activated, and typical items were reinstated more than atypical ones in several regions including the anterior temporal lobe. Results suggest that the centrality of this region in the processing of typicality extends to memory retrieval, and that the correct retrieval of typical items requires finer-grained, item-specific, processing, possibly to resolve their greater confusability with other category members.</p
Conceptual Knowledge Modulates the Temporal Dynamics of Novelty Preference for Real-world Objects in a Visual Paired Comparison Task
No full textOur visual system tends to prioritise novel information, and this allocation of attention, as examined with the Visual Paired Comparison Task (VPC), is taken as an indirect index of memory processes. At present, research on the emergence of a novelty preference (NP) remains unclear about its temporal dynamics and agnostic about the role that the organisation of conceptual knowledge may play in it. These two gaps are addressed in this eye-tracking study, which adapts the VPC task to enable a finer temporal tracking of the NP while manipulating categorical and functional relationships between pairs of real-world visual objects to examine the impact conceptual associations bear on it. We found that NP significantly increases with increasing delay between the familiarisation and the test phase, especially for pairs of objects that were both categorically and functionally related (e.g., dart/dartboard). Our findings provide fresh evidence about the interplay between overt attention, conceptual knowledge and memory processes on novelty preference while offering valuable insights into the temporal dynamics of NP and its conceptual implications for mechanisms governing visual short-term memory
Locations of objects are better remembered than their identities in naturalistic scenes:An eye-tracking experiment in mild cognitive impairment
Full text linkObjective: Retaining the identity or location of decontextualized objects in visual short-term working memory (VWM) is impaired by healthy and pathological ageing, but research remains inconclusive on whether these two features are equally impacted by it. Moreover, it is unclear whether similar impairments would manifest in naturalistic visual contexts. Method: 30 people with mild cognitive impairment (MCI) and 32 age-matched control participants (CPs) were eye-tracked within a change detection paradigm. They viewed 120 naturalistic scenes, and after a retention interval (1 s) asked whether a critical object in the scene had (or not) changed on either: identity (became a different object), location (same object but changed location), or both (changed in location and identity). Results: MCIs performed worse than CP but there was no interaction with the type of change. Changes in both were easiest while changes in identity alone were hardest. The latency to first fixation and first-pass duration to the critical object during successful recognition was not different between MCIs and CPs. Objects that changed in both features took longer to be fixated for the first time but required a shorter first pass compared to changes in identity alone which displayed the opposite pattern. Conclusions: Locations of objects are better remembered than their identities; memory for changes is best when involving both features. These mechanisms are spared by pathological ageing as indicated by the similarity between groups besides trivial differences in overall performance. These findings demonstrate that VWM mechanisms in the context of naturalistic scene information are preserved in people with MCI
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