Effects of categorical labels on similarity judgments: a critical analysis of similarity-based approaches

Sad expressions during encoding enhance facial identity recognition in visual working memory in depression: Behavioural and electrophysiological evidence

BACKGROUND

Mood-congruent memory biases are prominently featured in cognitive theories of depression. However, how sad expressions during encoding affect facial identity recognition in visual working memory (WM) and the electrophysiological correlates in depressed individuals are unclear.

METHODS

Event-related potentials (ERPs) were recorded from 30 depressed participants and 31 controls during a delayed face discrimination task.

RESULTS

The depressed participants showed lower discrimination power in facial identity recognition than the controls. However, the depressed participants showed higher discrimination power in facial identity recognition for neutral probe faces preceded by sad expressions than for those preceded by happy expressions, while the controls showed no difference. Furthermore, hits (correctly recognizing studied faces) and associated vertex positive potential (VPP), P3b, and late positive potential (LPP) amplitudes were significantly higher for probe faces preceded by sad expressions than for those preceded by happy expressions in the depressed individuals, whereas the controls showed no differences. No such effects were found for correct rejections (correctly rejecting unstudied faces).

LIMITATIONS

The present study is limited due to the relatively small sample size and homogenous university population.

CONCLUSIONS

The findings suggest that for depressed individuals, sad expressions during encoding enhanced discrimination power in facial identity recognition, especially correct recognition of studied faces in visual WM, which was associated with an increase in early structural encoding and more late attentional and perceptual resources following facial identity during retrieval, reflecting a mood-congruent memory bias.

Eleven-Month-Olds Link Sound Properties With Animal Categories

We examined 11-month-olds' tendency to generalize properties to category members, an ability that may contribute to the inductive reasoning abilities observed in later developmental periods. Across three experiments, we tested 11-month-olds' (N = 113) generalization of properties within the cat and dog categories. In each experiment, infants were familiarized to animal-sound pairings (i.e., dog barking; cat meowing) and tested on this association and the generalization of the sound property to new members of the familiarized categories. After familiarization with a single exemplar, 11-month-olds generalized the sound to new category members that were both highly similar and less similar to the familiarized animal (Experiment 1). When familiarized with mismatched animal-sound pairings (Experiment 2; i.e., dog meowing; cat barking), 11-month-olds did not learn or generalize the sound properties, suggesting that infants have pre-existing expectations about the links between the characteristic sound properties and the animal categories. When familiarized with unfamiliar sound-animal pairings (Experiment 3; i.e., dog-unfamiliar sound), 11-month-olds linked the animals with the novel sounds but did not generalize to new category members. Taken together, these findings highlight the conditions under which young infants generalize properties from one exemplar to other category members.

Sad expressions during encoding attenuate recognition of facial identity in visual working memory: behavioural and electrophysiological evidence

The current study investigated how sad expressions during encoding affected recognition of facial identity in visual working memory (WM) and its electrophysiological correlates. Event-related potentials were obtained from 36 individuals during a delayed face discrimination task. The hit (correctly recognising studied faces) rates, correct rejection (CR: correctly rejecting unstudied faces) rates, sensitivity d' (discrimination power of face identity recognition), and N170 (150-200 ms), the vertex positive potential (VPP; 150-200 ms), N250 (250-300 ms), P3b (350-450 ms), and late positive potential (LPP; 550-800 ms) amplitudes elicited by the neutral probe faces (previously encoded with sad and happy expressions) during hits and CR conditions were analysed. The participants showed lower hits and CRs and therefore had a lower discrimination power for facial identity preceded by sad expressions compared to happy expressions. For hits, neutral probe faces previously encoded with sad expressions exhibited increased N170, VPP, N250, P3b and LPP amplitudes compared to amplitudes following encoding with happy expressions. For correct rejections, the ERP effect of sad/happy expressions was absent. These results indicate that sad expressions during encoding attenuated the recognition of facial identity in visual WM. The reduced facial identity recognition for previously encoded sad expressions may be associated with increased early structural encoding, more late attention and perceptual resource engagement.

The influence of theoretical knowledge on similarity judgment

The similarity of the features between two entities has been assumed to be the essential factor for distinguishing these two entities across a variety of cognitive acts; however, the mechanism underlying the similarity processing remains unclear. The perceptual-based account suggests that similarity judgment is based on perceptual features between entities, whereas other accounts assume that similarity judgment relies heavily on one's previous knowledge of the entities. In Experiment 1, we explored the influence of theoretical knowledge on similarity judgment when perceptual features conflict with conceptual information. In Experiment 2, we examined whether categorization tasks further influence the results of the similarity judgment. Our results showed that the theoretical knowledge contributed to the overall similarity of the stimuli. In addition, carrying out a categorization task or not did not contribute more to the processes of the similarity judgment. Overall, these findings suggest that the conceptual information is more important than perceptual features while judging the similarity of two entities; if sufficient theoretical knowledge is available, the criteria for carrying out the categorization task might be consistent with those for the similarity judgment in the present study.

What the [beep]? Six-month-olds link novel communicative signals to meaning

Over the first year, infants tune into the signals of their native language and begin to link them to meaning. Here, we ask whether infants, like adults, can also infer the communicative function of otherwise arbitrary signals (here, tone sequences) and link these to meaning as well. We examined 6-month-olds' object categorization in the context of sine-wave tones, a signal that fails to support categorization at any point during their first year. However, before the categorization task, we exposed infants to tones in one of two vignettes. In one, the tones were produced by an actor in a rich communicative exchange; in the other, infants heard the very same tones, but these were uncoupled from the actors' activity. Infants exposed to the communicative vignette successfully formed object categories in the subsequent test; those exposed to the non-communicative vignette failed, performing identically to infants with no prior exposure to this novel signal. This reveals in 6-month-old infants a remarkable flexibility in identifying which signals in the ambient environment are communicative and in linking these signals to core cognitive capacities including categorization.

Conceptual influences on induction: A case for a late onset

This research examines the mechanism of early induction, the development of induction, and the ways attentional and conceptual factors contribute to induction across development. Different theoretical views offer different answers to these questions. Six experiments with 4- and 5-year-olds, 7-year-olds and adults (N=208) test these competing theories by teaching categories for which category membership and perceptual similarity are in conflict, and varying orthogonally conceptual and attentional factors that may potentially affect inductive inference. The results suggest that early induction is similarity-based; conceptual information plays a negligible role in early induction, but its role increases gradually, with the 7-year-olds being a transitional group. And finally, there is substantial contribution of attention to the development of induction: only adults, but not children, could perform category-based induction without attentional support. Therefore, category-based induction exhibits protracted development, with attentional factors contributing early in development and conceptual factors contributing later in development. These results are discussed in relation to existing theories of development of inductive inference and broader theoretical views on cognitive development.

Conceptually coherent categories support label-based inductive generalization in preschoolers

Why do words support inductive generalization in preschoolers? The current study provides evidence that they do so, at least in part, by working with conceptual knowledge to establish kind membership. A sample of 30 4-year-olds learned new labels for novel items, sometimes along with additional non-obvious information, and were then asked to generalize a novel object property to a target item based on either visual similarity or shared label. Children were more likely to generalize properties based on shared labels (over perceptual similarity) if they initially learned causally coherent properties of items referenced by those labels than if they initially learned non-causal properties of those items or learned no properties at all. This finding suggests that novel words best support inductive inference when they are known by children to reference conceptually coherent categories. Therefore, conceptual information permeates the process of inductive inference in young children. Results are discussed with respect to their implications for the "word-as-feature" and "knowledge-based" accounts of early inductive inference.

From perceptual to language-mediated categorization

From at least two months onwards, infants can form perceptual categories. During the first year of life, object knowledge develops from the ability to represent individual object features to representing correlations between attributes and to integrate information from different sources. At the end of the first year, these representations are shaped by labels, opening the way to conceptual knowledge. Here, we review the development of object knowledge and object categorization over the first year of life. We then present an artificial neural network model that models the transition from early perceptual categorization to categories mediated by labels. The model informs a current debate on the role of labels in object categorization by suggesting that although labels do not act as object features they nevertheless affect perceived similarity of perceptually distinct objects sharing the same label. The model presents the first step of an integrated account from early perceptual categorization to language-based concept learning.

Conceptual influences on category-based induction

One important function of categories is to permit rich inductive inferences. Prior work shows that children use category labels to guide their inductive inferences. However, there are competing theories to explain this phenomenon, differing in the roles attributed to conceptual information vs. perceptual similarity. Seven experiments with 4- to 5-year-old children and adults (N=344) test these theories by teaching categories for which category membership and perceptual similarity are in conflict, and varying the conceptual basis of the novel categories. Results indicate that for non-natural kind categories that have little conceptual coherence, children make inferences based on perceptual similarity, whereas adults make inferences based on category membership. In contrast, for basic- and ontological-level categories that have a principled conceptual basis, children and adults alike make use of category membership more than perceptual similarity as the basis of their inferences. These findings provide evidence in favor of the role of conceptual information in preschoolers' inferences, and further demonstrate that labeled categories are not all equivalent; they differ in their inductive potential.

Distinct labels attenuate 15-month-olds' attention to shape in an inductive inference task

We examined the role of distinct labels on infants' inductive inferences. Thirty-six 15-month-old infants were presented with target objects that possessed a non-obvious property, followed by test objects that varied in shape similarity relative to the target. Infants were tested in one of two groups, a Same Label group in which target and test objects were labeled with the same noun, and a Distinct Label group in which target and test objects were labeled with different nouns. When target and test objects were labeled with the same count noun, infants generalized the non-obvious property to both test objects, regardless of similarity to the target. In contrast, labeling the target and test objects with different count nouns attenuated infants' generalization of the non-obvious property to both high and low-similarity test objects. Our results suggest that by 15 months, infants recognize that object labels provide information about underlying object kind and appreciate that distinct labels are used to designate members of different categories.

Disentangling similarity judgments from pragmatic judgments: Response to Sloutsky and Fisher (2012)

Sloutsky and Fisher (2012) attempt to reframe the results presented in Noles and Gelman (2012) as a pure replication of their original work validating the similarity, induction, naming, and categorization (SINC) model. However, their critique fails to engage with the central findings reported in Noles and Gelman, and their reanalysis fails to examine the key comparison of theoretical interest. In addition to responding to the points raised in Sloutsky and Fisher's (2012) critique, we elaborate on the pragmatic factors and methodological flaws present in Sloutsky and Fisher (2004) that biased children's similarity judgments. Our careful replication of that study suggests that, rather than measuring the influence of labels on judgments of perceptual similarity, the original design measured sensitivity to the pragmatics of task demands. Together, the results reported in Noles and Gelman and the methodological problems highlighted here represent a serious challenge to the validity of the SINC model specifically and the words-as-features view more generally. (PsycINFO Database Record (c) 2012 APA, all rights reserved).