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This study explores how 7-month-old infants categorize graphical images varying in basic perceptual features by using a fast periodic visual stimulation (FPVS) task. Most participants were Caucasian and their parents had a higher education, but the family's socioeconomic background was mixed. Experiment 1 (N = 23) tested brain responses to configurational versus scrambled image sequences and found an oddball effect for both conditions, with configurational information leading to stronger neural responses. Experiment 2 explored the role of category learning for later FPVS performance: Group A (control; n = 22) participated in the FPVS categorization task only. Group B (fam; n = 21) was first familiarized with standard exemplars. Group C (fam + contrast; n = 29) was presented an additional exemplar of the contrasting category before the FPVS task. Electroencephalogram analyses revealed a decrease in Nc amplitude (measuring attention) throughout the familiarization phase. Long looking at the out-of-category exemplar in Group C indicated infants' visual interest. Brain responses in the subsequently presented FPVS were strong but did not differ between groups. This highlights the ability of the infant brain to organize perceptual input very rapidly without requiring familiarization but also points to the need for further studies exploring brain processes associated with infants' category learning and categorization at the brain level.

Adults and children easily distinguish between fine-grained variations in trustworthiness intensity based on facial appearance, but the developmental origins of this fundamental social skill are still debated. Using a fast periodic visual stimulation (FPVS) oddball paradigm coupled with electroencephalographic (EEG) recording, we investigated neural discrimination of morphed faces that adults perceive as low- and high-trustworthy in a sample of 6-month-old infants (N = 29; 56% male; M[subscript age] = 196.8 days; all White) and young adults (N = 21; 40% male; M[subscript age] = 24.61 years; all White) recruited in Italy. Stimulus sequences were presented at 6 Hz with deviant faces interleaved every fifth stimulus (i.e., 1.2 Hz); oddball category (high/low trustworthiness) was varied within subjects. FPVS responses were analyzed at both frequencies of interest and their harmonics as a function of deviant type (high- vs. low-trustworthy) over occipital and occipitolateral electrode clusters. For both infants and adults, the baseline response did not differ between trustworthiness conditions. Significant responses were centered on the right parietal electrodes in infants, and on the occipital and left occipitotemporal clusters in adults. Oddball responses were significant for both infants and adults, with cross-age differences in the topographical localization of the response on the scalp. Overall, results suggest that, by the age of 6 months, infants discriminate between faces that adults rate as high and low in trustworthiness, extending prior evidence of early sensitivity to this face dimension in humans.

This study investigates attention modulation as a function of infant directed (ID) versus adult directed (AD) speech in seven‐month‐old infants using electroencephalographic measures. In three experiments, infants were presented with either ID speech or AD speech as stimuli, followed by highly variable images of inanimate objects as targets. In Experiment 1 (N = 18), images were preceded by ID or AD speech with semantic content ("Look here"). Contrary to hypothesis, targets preceded by AD speech elicited increased amplitude of the Negative central (Nc) component compared to targets preceded by ID speech, indicating increased attention. Experiment 2 (N = 23) explored whether ID versus AD speech influences attention allocation also without semantic content. The same targets were either preceded by human voice sounds without semantic content ("Uh‐Ah") following the prosody of either ID or AD speech register. No differences in attention allocation or object processing were observed. Experiment 3 (N = 18) contrasted ID speech with and without semantic content and found enhanced attention allocation following stimuli without semantic content, but increased object processing following stimuli with semantic content. Overall, the effects observed here are consistent with the idea that less familiar speech stimuli increase attention for subsequent objects. Semantic content of stimuli increased the depth of object processing in 7‐month‐olds. [ABSTRACT FROM AUTHOR]

This study investigated the development of rapid visual object categorization. N = 20 adults (Experiment 1), N = 21 five to six‐year‐old children (Experiment 2), and N = 140 four‐, seven‐, and eleven‐month‐old infants (Experiment 3; all predominantly White, 81 females, data collected in 2013–2020) participated in a fast periodic visual stimulation electroencephalographic task. Similar categorization of animal and furniture stimuli emerged in children and adults, with responses much reduced by phase‐scrambling (R2 =.34–.73). Categorization was observed from 4 months, but only at 11 months, high‐level cues enhanced performance (R2 =.11). Thus, first signs of rapid categorization were evident from 4 months, but similar categorization patterns as in adults were recorded only from 11 months on. [ABSTRACT FROM AUTHOR]

Behavioural and recent neural evidence indicates that young infants discriminate broad stimulus categories. However, little is known about the categorical perception of humans represented as full bodies with heads and their discrimination from inanimate objects. This study compares infants' brain processing of human and furniture pictures, probing infants' categorization skills with an event-related potential (ERP) paradigm. Seven-month-old infants (n = 23) were tested in a rapid repetition ERP paradigm. Trials consisted of two consecutive stimuli: prime and target. Different ERP parameters (Nc, PSW) were compared across human and furniture items and for repeated and unrepeated categories. The PSW was consistently enhanced for unrepeated compared to repeated categories, thus indicating category discrimination. Nc amplitude was enhanced for furniture primes compared to human primes, but not for corresponding targets. In sum, these findings suggest that ERP rapid repetition studies are suitable for probing perceptual category discrimination in infancy. 7-month-olds discriminated between humans, presented as full body pictures, and furniture exemplars, but did not seem to prefer either of these categories.

The current study examines the processing of upright and inverted faces in 3-year-old children (n = 35). Event-related potentials (ERPs) were recorded during a passive looking paradigm including adult and newborn face stimuli. We observed three face-sensitive components, the P1, the N170 and the P400. Inverted faces elicited shorter P1 latency and larger P400 amplitude. P1 and N170 amplitudes were larger for adult faces. To examine the role of experience in the development of face processing, the processing of adult and newborn faces was compared for children with a younger sibling (n = 23) and children without a younger sibling (n = 12). Age of sibling at test correlated negatively with P1 amplitude for adult and newborn faces. This may indicate more efficient processing of different face ages in children with a younger sibling and potentially reflects a more flexible face representation.

Behavioural and recent neural evidence indicates that young infants discriminate broad stimulus categories. However, little is known about the categorical perception of humans represented as full bodies with heads and their discrimination from inanimate objects. This study compares infants' brain processing of human and furniture pictures, probing infants' categorization skills with an event-related potential (ERP) paradigm. Seven-month-old infants ( n = 23) were tested in a rapid repetition ERP paradigm. Trials consisted of two consecutive stimuli: prime and target. Different ERP parameters (Nc, PSW) were compared across human and furniture items and for repeated and unrepeated categories. The PSW was consistently enhanced for unrepeated compared to repeated categories, thus indicating category discrimination. Nc amplitude was enhanced for furniture primes compared to human primes, but not for corresponding targets. In sum, these findings suggest that ERP rapid repetition studies are suitable for probing perceptual category discrimination in infancy. 7-month-olds discriminated between humans, presented as full body pictures, and furniture exemplars, but did not seem to prefer either of these categories. Highlights 7-month-olds' ability to categorize humans and furniture items was tested using rapid repetition ERPs., The PSW was enhanced for unrepeated categories, indicating broad categorization., The Nc, indicating neural attention, was not enhanced for humans compared to furniture items. [ABSTRACT FROM AUTHOR]

To investigate whether infants show neural signatures of recognizing unfamiliar human faces, we tested 9-month-olds ( N = 31) in a rapid repetition ERP paradigm. Pictures of unfamiliar male and female faces (targets) were preceded either by a central attractor (Unprimed) or by a face (Primed). In the latter case, the prime faces were either identical to the target (Repeated) or not (Unrepeated). We compared processing of primed versus unprimed faces as well as processing of repeated versus unrepeated faces. Primed stimuli elicited decreased P1 amplitude, P1 latency and N290 amplitude, indicating categorical repetition effects very early during the stream of processing. For repeated relative to unrepeated faces, N290 latency was reduced. In addition, we observed an enhanced late positivity at occipital channels for unrepeated compared to repeated male faces, but no difference for female faces. Taken together, these results suggest that 9-month-olds categorize faces before discriminating them individually. Furthermore, infants' ability to recognize face identity seems to depend on familiarity with the given face category, as indicated by differences in brain responses to male and female faces. [ABSTRACT FROM AUTHOR]