Novelty and learning in cognitive control: evidence from the Simon task.

While information that is associated with inappropriate responses can interfere with an ongoing task and be detrimental to performance, cognitive control mechanisms and specific contextual conditions can alleviate interference from unwanted information. In the spatial correspondence (Simon) task, interference has been consistently shown to be reduced by spatial non-correspondence in the previous trial (i.e., correspondence sequence effect, CSE); however the mechanisms supporting this sequential effect are not well understood. Here we investigated the role of novelty and trial-to-trial changes in stimulus and response features in a Simon task, observing similar modulation of CSE for novel and non-novel stimulus changes. However, changing the response modality from trial to trial dampened CSE, and this dampening was more pronounced when the probability of switch trials was higher, suggesting a role for long-term learning. The results are consistent with recent accounts, which indicate that spatial interference can be prevented by cognitive control mechanisms triggered by learned bindings.

Contextual Modulation of Emotional Distraction: Attentional Capture and Motivational Significance.

Emotional stimuli engage corticolimbic circuits and capture attention even when they are task-irrelevant distractors. Whether top-down or contextual factors can modulate the filtering of emotional distractors is a matter of debate. Recent studies have indicated that behavioral interference by emotional distractors habituates rapidly when the same stimuli are repeated across trials. However, little is known as to whether we can attenuate the impact of novel (never repeated) emotional distractors when they occur frequently. In two experiments, we investigated the effects of distractor frequency on the processing of task-irrelevant novel pictures, as reflected in both behavioral interference and neural activity, while participants were engaged in an orientation discrimination task. Experiment 1 showed that, compared with a rare distractor condition (20%), frequent distractors (80%) reduced the interference of emotional stimuli. Moreover, Experiment 2 provided evidence that emotional interference was reduced by distractor frequency even when rare, and unexpected, emotional distractors appeared among frequent neutral distractors. On the other hand, in both experiments, the late positive potential amplitude was enhanced for emotional, compared with neutral, pictures, and this emotional modulation was not reduced when distractors were frequently presented. Altogether, these findings suggest that the high occurrence of task-irrelevant stimuli does not proactively prevent the processing of emotional distractors. Even when attention allocation to novel emotional stimuli is reduced, evaluative processes and the engagement of motivational systems are needed to support the monitoring of the environment for significant events.

Categorization Goals Modulate the Use of Natural Scene Statistics.

Understanding natural scenes involves the contribution of bottom-up analysis and top-down modulatory processes. However, the interaction of these processes during the categorization of natural scenes is not well understood. In the current study, we approached this issue using ERPs and behavioral and computational data. We presented pictures of natural scenes and asked participants to categorize them in response to different questions (Is it an animal/vehicle? Is it indoors/outdoors? Are there one/two foreground elements?). ERPs for target scenes requiring a "yes" response began to differ from those of nontarget scenes, beginning at 250 msec from picture onset, and this ERP difference was unmodulated by the categorization questions. Earlier ERPs showed category-specific differences (e.g., between animals and vehicles), which were associated with the processing of scene statistics. From 180 msec after scene onset, these category-specific ERP differences were modulated by the categorization question that was asked. Categorization goals do not modulate only later stages associated with target/nontarget decision but also earlier perceptual stages, which are involved in the processing of scene statistics.

Evaluative ratings and attention across the life span: emotional arousal and gender.

This study was designed to investigate the evolution of emotional processing over the whole adult life span as a function of stimulus arousal and participants' gender. To this end, self-reported affective evaluation and attentional capture prompted by pleasant and unpleasant pictures varying in arousal were measured in a large sample of participants (n = 211) balanced by gender and equally spread across seven decades from 20 to 90 years. Results showed age differences only for affective evaluation of pleasant stimuli, with opposite patterns depending on stimulus arousal. As age increased, low-arousing pleasant cues (e.g. images of babies) were experienced as more pleasant and arousing by both males and females, whereas high-arousing stimuli (e.g. erotic images) were experienced as less pleasant only by females. In contrast, emotional pictures (both pleasant and unpleasant) were effective at capturing attention in a similar way across participants, regardless of age and gender. Taken together, these findings suggest that specific emotional cues prompt different subjective responses across different age groups, while basic mechanisms involved in attentional engagement towards both pleasant and unpleasant stimuli are preserved in healthy ageing.

The fate of unattended stimuli and emotional habituation: Behavioral interference and cortical changes.

The interference produced by the viewing of emotional distractors has been interpreted as evidence that emotional cues are processed in a fairly mandatory fashion, and that they divert attention from the primary ongoing task. However, few studies have examined how behavioral emotional interference varies with repeated presentation of the same emotional distractors. In two experiments, while participants were engaged in a parity judgment task, we investigated the effects of repetition of task-irrelevant emotional pictures, as reflected in both behavioral interference (Experiments 1 and 2) and neural activity (Experiment 2). Both experiments showed that the slowing of reaction times that was observed when viewing emotional, compared to neutral, scenes disappeared after only a few repetitions, suggesting diminished attention allocation to repeated emotional pictures. Conversely, in Experiment 2, neural correlates of picture processing revealed that the late positive potential (LPP) amplitude continued to be enhanced for emotional, compared to neutral, distractors despite picture repetition and the presence of a concurrent task. Altogether, these findings suggest that while evaluative processes are mandatory, and continue to engage cortico-limbic appetitive and defensive systems even after massive repetition, as suggested by the affective modulation of the LPP, attentional processes are not necessary after several repetitions of the same stimulus, as indicated by the rapid decline of behavioral emotional interference.

Imaging distributed and massed repetitions of natural scenes: spontaneous retrieval and maintenance.

Repetitions that are distributed (spaced) across time prompt enhancement of a memory-related event-related potential, compared to when repetitions are massed (contiguous). Here, we used fMRI to investigate neural enhancement and suppression effects during free viewing of natural scenes that were either novel or repeated four times with massed or distributed repetitions. Distributed repetition was uniquely associated with a repetition enhancement effect in a bilateral posterior parietal cluster that included the precuneus and posterior cingulate and which has previously been implicated in episodic memory retrieval. Unique to massed repetition, conversely, was enhancement in a right dorsolateral prefrontal cluster that has been implicated in short-term maintenance. Repetition suppression effects for both types of spacing were widespread in regions activated during novel picture processing. Taken together, the data are consistent with a hypothesis that distributed repetition prompts spontaneous retrieval of prior occurrences, whereas massed repetition prompts short-term maintenance of the episodic representation, due to contiguous presentation. These processing differences may mediate the classic spacing effect in learning and memory.

Memory for faces: the effect of facial appearance and the context in which the face is encountered.

We investigated the effects of appearance of emotionally neutral faces and the context in which the faces are encountered on incidental face memory. To approximate real-life situations as closely as possible, faces were embedded in a newspaper article, with a headline that specified an action performed by the person pictured. We found that facial appearance affected memory so that faces perceived as trustworthy or untrustworthy were remembered better than neutral ones. Furthermore, the memory of untrustworthy faces was slightly better than that of trustworthy faces. The emotional context of encoding affected the details of face memory. Faces encountered in a neutral context were more likely to be recognized as only familiar. In contrast, emotionally relevant contexts of encoding, whether pleasant or unpleasant, increased the likelihood of remembering semantic and even episodic details associated with faces. These findings suggest that facial appearance (i.e., perceived trustworthiness) affects face memory. Moreover, the findings support prior evidence that the engagement of emotion processing during memory encoding increases the likelihood that events are not only recognized but also remembered.

Modulation of early ERPs by accurate categorization of objects in scenes.

The categorization of objects within natural scenes is carried out in a sequence of stages, which may build on the detection of perceptual regularities in the visual appearance of objects or may represent a more semantic level of categorization. Here, we examined the neural correlates of correct categorization of objects in scenes, using natural scenes which were equalized in color and spectral amplitude, and controlled in terms of spatial coherence. Event-related potentials (ERPs) were used to track the early stages of visual processing. Participants viewed degraded (phase-scrambled) versions of natural scenes and then categorized them as depicting animals or people. At an intermediate scrambling level, a negative-going occipitotemporal ERP modulation by categorization accuracy was observed, beginning approximately 150 ms after stimulus onset; at more degraded levels, no ERP modulation was observed. These results suggest that this early negative-going ERP modulation reflects processing of perceptual evidence which is predictive of later correct categorization, even when low-level differences in color, spectral amplitude, and spatial coherence are balanced or controlled.

Subjective Affective Responses to Natural Scenes Require Understanding, Not Spatial Frequency Bands.

It is debated whether emotional processing and response depend on semantic identification or are preferentially tied to specific information in natural scenes, such as global features or local details. The present study aimed to further examine the relationship between scene understanding and affective response while manipulating visual content. To this end, we presented affective and neutral natural scenes which were progressively band-filtered to contain global features (low spatial frequencies) or local details (high spatial frequencies) and assessed both affective response and scene understanding. We observed that, if scene content was correctly reported, subjective ratings of arousal and valence were modulated by the affective content of the scene, and this modulation was similar across spatial frequency bands. On the other hand, no affective modulation of subjective ratings was observed if picture content was not correctly reported. The present results indicate that subjective affective response requires content understanding, and it is not tied to a specific spatial frequency range.

Sustained training with novel distractors attenuates the behavioral interference of emotional pictures but does not affect the electrocortical markers of emotional processing.

Introduction: Research has recently shown that behavioral interference prompted by emotional distractors is subject to habituation when the same exemplars are repeated, but promptly recovers in response to novel stimuli. The present study investigated whether prolonged experience with distractors that were all novel was effective in shaping the attentional filter, favoring stable and generalizable inhibition effects. Methods: To test this, the impact of emotional distractors was measured before and after a sustained training phase with only novel distractor pictures, and that for a group of participants depicted only a variety of neutral contents, whereas a different group was exposed only to emotional contents. Results: Results showed that emotional interference on reaction times was attenuated after the training phase (compared to the pre-test), but emotional distractors continued to interfere more than neutral ones in the post-test. The two groups did not differ in terms of training effect, suggesting that the distractor suppression mechanism developed during training was not sensitive to the affective category of natural scenes with which one had had experience. The affective modulation of neither the LPP or Alpha-ERD showed any effect of training. Discussion: Altogether, these findings suggest that sustained experience with novel distractors may attenuate attention allocation toward task irrelevant emotional stimuli, but the evaluative processes and the engagement of motivational systems are always needed to support the monitoring of the environment for significant cues.

Spatial frequencies and emotional perception.

It has been suggested that, during evolution, specific mechanisms developed in order to optimize the detection of threats and opportunities even in perceptually degraded conditions. A naturalistic example of perceptual degradation can be found in blurry images, which contain the coarsest elements of a scene (low spatial frequencies) but lack the fine-grained details (high spatial frequencies). In the past decade, several studies have examined the relation between spatial frequencies and emotions, using a variety of methods, stimuli, and rationales. Here, we conduct a literature survey on the studies that have examined the relation between emotion and spatial frequencies. Some studies have suggested that the low spatial frequencies of emotional stimuli may be processed by a subcortical neural pathway, eventually eliciting emotional responses. However, the evidence provided by the reviewed studies does not support this possibility, for conceptual and methodological reasons (e.g., mistaking the processing of a fuzzy stimulus for subcortical processing). Here, the conceptual and methodological problems present in the reviewed studies are analyzed and discussed, along with suggestions for future research.

Visual-cortical enhancement by acoustic distractors: The effects of endogenous spatial attention and visual working memory load.

Past work has shown that when a peripheral sound captures our attention, it activates the contralateral visual cortex as revealed by an event-related potential component labelled the auditory-evoked contralateral occipital positivity (ACOP). This cross-modal activation of the visual cortex has been observed even when the sounds were not relevant to the ongoing task (visual or auditory), suggesting that peripheral sounds automatically activate the visual cortex. However, it is unclear whether top-down factors such as visual working memory (VWM) load and endogenous attention, which modulate the impact of task-irrelevant information, may modulate this spatially-specific component. Here, we asked participants to perform a lateralized VWM task (change detection), whose performance is supported by both endogenous spatial attention and VWM storage. A peripheral sound that was unrelated to the ongoing task was delivered during the retention interval. The amplitude of sound-elicited ACOP was analyzed as a function of the spatial correspondence with the cued hemifield, and of the memory array set-size. The typical ACOP modulation was observed over parieto-occipital sites in the 280-500 ms time window after sound onset. Its amplitude was not affected by VWM load but was modulated when the location of the sound did not correspond to the hemifield (right or left) that was cued for the change detection task. Our results suggest that sound-elicited activation of visual cortices, as reflected in the ACOP modulation, is unaffected by visual working memory load. However, endogenous spatial attention affects the ACOP, challenging the hypothesis that it reflects an automatic process.

Alpha-band oscillations and emotion: A review of studies on picture perception.

Although alpha-band activity has long been a focus of psychophysiological research, its modulation by emotional value during picture perception has only recently been studied systematically. Here, we review these studies and report that the most consistent alpha oscillatory pattern indexing emotional processing is an enhanced desynchronization (ERD) over posterior sensors when viewing emotional compared with neutral pictures. This enhanced alpha ERD is not specific to unpleasant picture content, as previously proposed for other measures of affective response, but has also been observed for pleasant stimuli. Evidence suggests that this effect is not confined to the alpha band but that it also involves a desynchronization of the lower beta frequencies (8-20 Hz). The emotional modulation of alpha ERD occurs even after massive stimulus repetition and when emotional cues serve as task-irrelevant distractors, consistent with the hypothesis that evaluative processes are mandatory in emotional picture processing. A similar enhanced ERD has been observed for other significant cues (e.g., conditioned aversive stimuli, or in anticipation of a potential threat), suggesting that it reflects cortical excitability associated with the engagement of the motivational systems.

Delayed ocular disengagement from arousing scenes.

Visual exploration of the world is supported by eye movements which can be speeded up or delayed depending on bottom-up stimulation, top-down goals, and prior associations. Previous studies observed faster initiation of saccades toward emotional than neutral natural scenes; however, less is known concerning saccades which originate from emotional, compared with neutral, scenes. Here, we addressed this issue by examining a task in which participants continuously moved their gaze from and toward pictures (natural scenes), which could be emotional or neutral, and changed position in every trial. Saccades were initiated later when the starting picture was emotional compared to neutral, and this slowing was associated with the arousal value of the picture, suggesting that ocular disengagement does not vary with stimulus valence but is affected by engaging picture contents such as erotica and threat/injuries.

Scene identification and emotional response: which spatial frequencies are critical?

Emotional responses are regulated by basic motivational systems (appetitive and defensive), which allow for adaptive behavior when opportunities and threats are detected. It has been suggested that specific ranges of spatial frequencies of the visual input may contain information that is diagnostic for discriminating emotionally relevant from less relevant contents, and that specialized neural modules may analyze these spatial frequencies to allow efficient detection and response to life-threatening or life-sustaining stimuli. However, there is no evidence supporting this possibility regarding natural scenes, which are highly varied in terms of pictorial composition. The present study examines how low and high spatial frequency filtering affects the understanding of natural scene contents and modulates the amplitude of the late positive potential (LPP), a well-known component of the event-related potentials that reflects motivational significance. The content of an initially degraded (low- or high-passed) picture was progressively revealed in a sequence of steps by adding high or low spatial frequencies. At each step, human participants reported whether they identified the gist of the image. The results showed that the affective modulation of the LPP varied with picture identification similarly for low-passed and high-passed pictures. The engagement of corticolimbic appetitive and defensive systems, reflected in the LPP affective modulation, varied with picture identification, and did not critically or preferentially depend on either low or high spatial frequencies.

Eye tracking applied to tobacco smoking: current directions and future perspectives.

Over the years the general awareness of the health costs associated with tobacco smoking has motivated scientists to apply the measurement of eye movements to this form of addiction. On one hand they have investigated whether smokers attend and look preferentially at smoking related scenes and objects. In parallel, on the other hand eye tracking has been used to test how smokers and nonsmokers interact with the different types of health warning that policymakers have mandated in tobacco advertisements and packages. Here we provide an overview of the main findings from the different lines of research, such as the evidence related to the attentional bias for smoking cues in smokers and the evidence that graphic warning labels and plain packages measurably increase the salience of the warning labels. We point to some open questions, such as the conditions that determine whether heavy smokers exhibit a tendency to actively avoid looking at graphic warning labels. Finally we argue that the research applied to gaze exploration of warning labels would benefit from a more widespread use of the more naturalistic testing conditions (e.g. mobile eye tracking or virtual reality) that have been introduced to study the smokers' attentional bias for tobacco-related objects when freely exploring the surrounding environment.

Stimulus novelty and emotionality interact in the processing of visual distractors.

Novel distractors are prioritized for attentional selection. When distractors also convey emotional content, they divert attention from the primary task more than neutral stimuli do. In the present study, while participants were engaged in a central task, we examined the impact of peripheral distractors that varied for emotional content and novelty. Results showed that emotional interference on reaction times completely habituated with repetition and promptly recovered with novelty. The enhanced LPP for emotional pictures was attenuated by repetitions and, interestingly, stimulus novelty only affected emotional, but not neutral distractors, in both the RTs and LPP. Alpha-ERD was similarly reduced for repeated emotional and neutral distractors. Altogether, these findings suggest that the impact of peripheral distractors can be attenuated through a non-strategic learning mechanism mediated by mere stimulus repetition, which is fine-tuned to detect changes in emotional distractors only, supporting the hypothesis that novelty and emotion share the same motivational circuits.

Luminance and timing control during visual presentation of natural scenes.

In the study of visual cognition, accurate control of stimulus presentation is of primary importance yet is complicated by hardware malfunctioning, software variability, and visual materials used. Here, we describe VISTO 2.0, a low-cost and open-source device which is capable to measure the timing and temporal luminance profile of visual stimuli. This device represents a major improvement over VISTO (De Cesarei, Marzocchi, & Loftus, 2021), as it is only sensitive to a light spectrum in the visible range, is easier to assemble, and has a modular design that can be extended to other sensory modalities.

Detecting novelty and significance.

Studies of cognition often use an "oddball" paradigm to study effects of stimulus novelty and significance on information processing. However, an oddball tends to be perceptually more novel than the standard, repeated stimulus as well as more relevant to the ongoing task, making it difficult to disentangle effects due to perceptual novelty and stimulus significance. In the current study, effects of perceptual novelty and significance on ERPs were assessed in a passive viewing context by presenting repeated and novel pictures (natural scenes) that either signaled significant information regarding the current context or not. A fronto-central N2 component was primarily affected by perceptual novelty, whereas a centro-parietal P3 component was modulated by both stimulus significance and novelty. The data support an interpretation that the N2 reflects perceptual fluency and is attenuated when a current stimulus matches an active memory representation and that the amplitude of the P3 reflects stimulus meaning and significance.

Time will tell: Object categorization and emotional engagement during processing of degraded natural scenes.

The aim of the present study was to examine the relationship between object categorization in natural scenes and the engagement of cortico-limbic appetitive and defensive systems (emotional engagement) by manipulating both the bottom-up information and the top-down context. Concerning the bottom-up information, we manipulated the computational load by scrambling the phase of the spatial frequency spectrum, and asked participants to classify natural scenes as containing an animal or a person. The role of the top-down context was assessed by comparing an incremental condition, in which pictures were progressively revealed, to a condition in which no probabilistic relationship existed between each stimulus and the following one. In two experiments, the categorization and response to emotional and neutral scenes were similarly modulated by the computational load. The Late Positive Potential (LPP) was affected by the emotional content of the scenes, and by categorization accuracy. When the phase of the spatial frequency spectrum was scrambled by a large amount (>58%), chance categorization resulted, and affective LPP modulation was eliminated. With less degraded scenes, categorization accuracy was higher (.82 in Experiment 1, .86 in Experiment 2) and affective modulation of the LPP was observed at a late window (>800 ms), indicating that it is possible to delay the time of engagement of the motivational systems which are responsible for the LPP affective modulation. The present data strongly support the view that semantic analysis of visual scenes, operationalized here as object categorization, is a necessary condition for emotional engagement at the electrocortical level (LPP).