Spontaneous and directed attention to number and proportion.

Although difficulties processing both symbolic and nonsymbolic proportion compared with absolute number are well established, the mechanisms involved remain unclear. We investigate four potential explanations to account for better number processing in adulthood: (a) number is more salient than proportion, (b) number is encoded more automatically than proportion, (c) proportion is more effortfully processed than number, and (d) number competes with proportion during decision making. Across three experiments, we used a delayed match-to-sample paradigm in which adults were asked which of two alternatives matched a sample set of red and blue dots. We systematically manipulated which dimension of the sample participants matched (number of red dots, total number of dots, proportion of red dots), the presence/absence of the competing quantity in the choice alternatives, and when they were told which quantitative dimension to encode (before vs. after the sample presentation, or not at all). Overall, data reveal that proportion was less salient than the numerical subset. Additionally, the number of items within the subset, but not the total number of items in the superset, interfered with proportion-based responding. Last, even in the absence of response competition and costly task demands, proportion matching took longer than number matching, highlighting basic processing differences. Together, results reveal pervasive difficulties in representing proportion compared with number, even when task demands are unambiguous. However, this varied depending on the numerical set involved and across encoding, processing, and decision processes. We discuss the implications of these findings for theories of ratio processing and of quantity more generally. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Author Correction: A consensus-based transparency checklist.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

The temporal dynamics of infants' joint attention: Effects of others' gaze cues and manual actions.

Infants' development of joint attention shows significant advances between 9 and 12 months of age, but we still need to learn much more about how infants coordinate their attention with others during this process. The objective of this study was to use eye tracking to systematically investigate how 8- and 12-month-old infants as well as adults dynamically select their focus of attention while observing a social partner demonstrate infant-directed actions. Participants were presented with 16 videos of actors performing simple infant-directed actions from a first-person perspective. Looking times to faces as well as hands-and-objects were calculated for participants at each age, and developmental differences were observed, although all three groups looked more at hands-and-objects than at faces. In order to assess whether visual attention was coordinated with the actors' behaviors, we compared participants looking at faces and objects in response to gaze direction as well as infant-directed actions vs. object-directed actions. By presenting video stimuli that involved continuously changing actions, we were able to document that the likelihood of joint attention changes in both real and developmental time. Overall, adults and 12-month-old infants' visual attention was modulated by gaze cues as well as actions, whereas this was only partially true for 8-month-old infants. Our results reveal that joint attention is not a monolithic process nor does it develop all at once.

Direct gaze, eye movements, and covert and overt social attention processes.

The present study is a replication and extension of previous research examining the effects of others' gaze direction and gaze shifts on both participants' (N = 32) manual responses, as an indicator of covert processes, and their visual attention, as an indicator of overt processes, within an experimental response time (RT) paradigm, under both fixed- and free-viewing instructions. Participants viewed arrays of faces displaying direct or averted gaze, which shifted or held their gaze, concurrent with the presentation of a target letter that participants had to identify overlaid on one face, all while their gaze was recorded with an eye-tracking system. Participants' RTs and eye movements both revealed faster responses when the target face displayed either direct or shifted gaze, and especially when its gaze had shifted from averted to direct, though these effects were modulated by the viewing instructions. Thus, the findings replicate and extend previous research by revealing that direct gaze and dynamic motion onset affect both covert and overt attention.

Infants' motor simulation of observed actions is modulated by the visibility of the actor's body.

Previous research suggests that 9-month-old infants will develop a response bias in the A-not-B search paradigm after only observing an experimenter search for a hidden object on A-trials. In the current experiment, we tested whether infants would persist in making errors when only the hands-and-arms of the experimenter were visible. Three different conditions were included: (1) the experimenter was silent while hiding and finding the object, (2) the experimenter communicated with the infant via infant-directed speech, or (3) the body of the experimenter was visible during the training phase before his head and body were occluded during the test phase. Unlike previous studies, the results revealed that a significant proportion of infants searched correctly when the body of the experimenter was not visible, and only the combination of infant-directed speech and familiarization with a fully-specified body resulted in a majority of infants committing search errors. These results are interpreted as suggesting that the likelihood of infants committing search errors is dependent on their motor simulation of the experimenter's reaching. The strength of this simulation is graded by the similarity between the observed action and the motor representation.

Attention to body-parts varies with visual preference and verb-effector associations.

Theories of embodied conceptual meaning suggest fundamental relations between others' actions, language, and our own actions and visual attention processes. Prior studies have found that when people view an image of a neutral body in a scene they first look toward, in order, the head, torso, hands, and legs. Other studies show associations between action verbs and the body-effectors used in performing the action (e.g., "jump" with feet/legs; "talk" with face/head). In the present experiment, the visual attention of participants was recorded with a remote eye-tracking system while they viewed an image of an actor pantomiming an action and heard a concrete action verb. Participants manually responded whether or not the action image was a good example of the verb they heard. The eye-tracking results confirmed that participants looked at the head most, followed by the hands, and the feet least of all; however, visual attention to each of the body-parts also varied as a function of the effector associated with the spoken verb on image/verb congruent trials, particularly for verbs associated with the legs. Overall, these results suggest that language influences some perceptual processes; however, hearing auditory verbs did not alter the previously reported fundamental hierarchical sequence of directed attention, and fixations on specific body-effectors may not be essential for verb comprehension as peripheral visual cues may be sufficient to perform the task.

Isolated processing of geometric shapes and their corresponding shape words: Evidence from a delayed match-to-sample task.

Some theorists propose a domain-specific cognitive system dedicated to processing geometric information, but existence of this system remains debatable because of challenges in isolating geometric from linguistic and semantic processing. Recently, Sturz, Edwards, and Boyer (2014) developed a delayed match-to-sample task that presented a sample of a shape, shape word, or bidimensional stimulus composed of a shape and shape word. After a delay, participants identified the sample shape or the sample word by selecting between 2 shapes or 2 shape words. An asymmetrical pattern of interference emerged such that increased response times (RTs) and errors occurred in matching shape targets but not word targets. This was interpreted as shape words activating a semantic and spatial representation of shapes, but shapes only activating a spatial representation. The present experiments attempted to replicate and extend these results by manipulating figure-ground relations to contrast the original condition with an alternative to address an explanation based upon sample shape saliency (Experiment 1), by confirming the effectiveness of the saliency manipulation (Experiment 2), and by explicitly testing the assumption that shapes did not activate a semantic representation by reversing the sample-to-target matching criteria (Experiment 3). Experiment 1 replicated the asymmetrical pattern of results for both conditions, and Experiment 2 confirmed the saliency manipulation, which together undermine a pure saliency explanation. Experiment 3 produced a symmetrical pattern of results and suggests that the reversed matching criteria forced shapes to be processed in both a spatial and semantic fashion. These results provide support for a cognitive system dedicated to processing geometric information isolated from linguistic and semantic processing. (PsycINFO Database Record

Infants' observation of others' actions: Brief movement-specific visual experience primes motor representations.

Recent research suggests that infants' observation of others' reaching actions activates corresponding motor representations which develop with their motor experience. Contralateral reaching develops a few months later than ipsilateral reaching, and 9-month-old infants are less likely to map the observation of these reaches to their motor representations. The goal of the current study was to test whether a brief familiarization with contralateral reaching is sufficient to prime this less developed motor representation to increase the likelihood of its activation. In Experiment 1, infants were familiarized with contralateral reaching before they were tested in an observational version of the A-not-B paradigm. A significant number of infants searched incorrectly, suggesting that the observation of contralateral reaching primed their motor representations. In Experiment 2, infants were familiarized with ipsilateral reaching, which shared the goals but not the movements associated with the contralateral reaches observed during testing, and they did not show a search bias. Taken together, these results suggest that a brief familiarization with a movement-specific behaviour facilitates the direct matching of observed and executed actions.

Disfluent fonts don't help people solve math problems.

Prior research suggests that reducing font clarity can cause people to consider printed information more carefully. The most famous demonstration showed that participants were more likely to solve counterintuitive math problems when they were printed in hard-to-read font. However, after pooling data from that experiment with 16 attempts to replicate it, we find no effect on solution rates. We examine potential moderating variables, including cognitive ability, presentation format, and experimental setting, but we find no evidence of a disfluent font benefit under any conditions. More generally, though disfluent fonts slightly increase response times, we find little evidence that they activate analytic reasoning.

Prompting children to reason proportionally: Processing discrete units as continuous amounts.

Recent studies reveal that children can solve proportional reasoning problems presented with continuous amounts that enable intuitive strategies by around 6 years of age but have difficulties with problems presented with discrete units that tend to elicit explicit count-and-match strategies until at least 10 years of age. The current study tests whether performance on discrete unit problems might be improved by prompting intuitive reasoning with continuous-format problems. Participants were kindergarten, second-grade, and fourth-grade students (N = 194) assigned to either an experimental condition, where they were given continuous amount proportion problems before discrete unit proportion problems, or a control condition, where they were given all discrete unit problems. Results of a three-way mixed-model analysis of variance examining school grade, experimental condition, and block of trials indicated that fourth-grade students in the experimental condition outperformed those in the control condition on discrete unit problems in the second half of the experiment, but kindergarten and second-grade students did not differ by condition. This suggests that older children can be prompted to use intuitive strategies to reason proportionally.

Signal clarity: an account of the variability in infant quantity discrimination tasks.

Infants have shown variable success in quantity comparison tasks, with infants of a given age sometimes successfully discriminating numerical differences at a 2:3 ratio but requiring 1:2 and even 1:4 ratios of change at other times. The current explanations for these variable results include the two-systems proposal - a theoretical framework that suggests that there are multiple systems at play and that these systems do not communicate early in infancy, leading to failure in certain numerical comparisons. An alternative proposal is that infants may be attending to continuous extent dimensions in these tasks rather than number per se. However, neither of these two main proposals is independently capable of accounting for the previously published data. Recently the Signal Clarity Hypothesis was proposed to account for and predict the variability (Cantrell & Smith, 2013). According to this hypothesis, infants' variable success may be understood from a framework of statistical learning taken together with the signal-to-noise ratio generated by control procedures in habituation tasks. Here we test specific predictions made by the Signal Clarity Hypothesis. Across four experiments assessing 9-month old discriminations of small and large sets (2 vs. 4 and 3 vs. 4), we demonstrate that infant success can be predicted by this novel approach and, further, that infants may discriminate smaller ratios of change than previously believed (3:4 numerical change and 2:3 cumulative area change).

When do infants begin to follow a point?

Infants' understanding of a pointing gesture represents a major milestone in their communicative development. The current consensus is that infants are not capable of following a pointing gesture until 9-12 months of age. In this article, we present evidence from 4- and 6-month-old infants challenging this conclusion. Infants were tested with a spatial cueing paradigm in Experiment 1 (500-ms stimulus-target onset asynchrony [SOA]) and Experiment 2 (100-ms SOA). The results revealed that the younger infants shifted their attention in the cued direction when presented with a pointing gesture and with a foil (i.e., same size and shape as pointing gesture) at both SOAs. Older infants shifted their attention only in response to the pointing gesture at 100-ms SOA. Experiment 3 tested infants' preferences for the social stimulus (i.e., pointing gesture) relative to the foil and a non-social stimulus (i.e., an arrow). The results revealed that infants are biased to selectively attend to the pointing gesture. Taken together, these results suggest that 4- and 6-month-old infants are capable of preferentially selecting and following a pointing gesture. It is theorized that this early capacity assists infants in their developing understanding of triadic forms of communication.

Asymmetrical interference effects between two-dimensional geometric shapes and their corresponding shape words.

Nativists have postulated fundamental geometric knowledge that predates linguistic and symbolic thought. Central to these claims is the proposal for an isolated cognitive system dedicated to processing geometric information. Testing such hypotheses presents challenges due to difficulties in eliminating the combination of geometric and non-geometric information through language. We present evidence using a modified matching interference paradigm that an incongruent shape word interferes with identifying a two-dimensional geometric shape, but an incongruent two-dimensional geometric shape does not interfere with identifying a shape word. This asymmetry in interference effects between two-dimensional geometric shapes and their corresponding shape words suggests that shape words activate spatial representations of shapes but shapes do not activate linguistic representations of shape words. These results appear consistent with hypotheses concerning a cognitive system dedicated to processing geometric information isolated from linguistic processing and provide evidence consistent with hypotheses concerning knowledge of geometric properties of space that predates linguistic and symbolic thought.

Stroop interference in a delayed match-to-sample task: evidence for semantic competition.

Discussions of the source of the Stroop interference effect continue to pervade the literature. Semantic competition posits that interference results from competing semantic activation of word and color dimensions of the stimulus prior to response selection. Response competition posits that interference results from competing responses for articulating the word dimension vs. the color dimension at the time of response selection. We embedded Stroop stimuli into a delayed match-to-sample (DMTS) task in an attempt to test semantic and response competition accounts of the interference effect. Participants viewed a sample color word in black or colored fonts that were congruent or incongruent with respect to the color word itself. After a 5 s delay, participants were presented with two targets (i.e., a match and a foil) and were instructed to select the correct match. We probed each dimension independently during target presentations via color targets (i.e., two colors) or word targets (i.e., two words) and manipulated whether the semantic content of the foil was related to the semantic content of the irrelevant sample dimension (e.g., word sample "red" in blue font with the word "red" as the match and the word "blue" as the foil). We provide evidence for Stroop interference such that response times (RTs) increased for incongruent trials even in the presence of a response option with semantic content unrelated to the semantic content of the irrelevant sample dimension. Accuracy also deteriorated during the related foil trials. A follow-up experiment with a 10 s delay between sample and targets replicated the results. Results appear to provide converging evidence for Stroop interference in a DMTS task in a manner that is consistent with an explanation based upon semantic competition and inconsistent with an explanation based upon response competition.

Probabilistic cue combination: less is more.

Learning about the structure of the world requires learning probabilistic relationships: rules in which cues do not predict outcomes with certainty. However, in some cases, the ability to track probabilistic relationships is a handicap, leading adults to perform non-normatively in prediction tasks. For example, in the dilution effect, predictions made from the combination of two cues of different strengths are less accurate than those made from the stronger cue alone. Here we show that dilution is an adult problem; 11-month-old infants combine strong and weak predictors normatively. These results extend and add support for the less is more hypothesis: limited cognitive resources can lead children to represent probabilistic information differently from adults, and this difference in representation can have important downstream consequences for prediction.

Differential contributions of development and learning to infants' knowledge of object continuity and discontinuity.

Sixty infants divided evenly between 5 and 7 months of age were tested for their knowledge of object continuity versus discontinuity with a predictive tracking task. The stimulus event consisted of a moving ball that was briefly occluded for 20 trials. Both age groups predictively tracked the ball when it disappeared and reappeared via occlusion, but not when it disappeared and reappeared via implosion. Infants displayed high levels of predictive tracking from the first trial in the occlusion condition, and showed significant improvement across trials in the implosion condition. These results suggest that infants possess embodied knowledge to support differential tracking of continuously and discontinuously moving objects, but this tracking can be modified by visual experience.

Is automatic imitation a specialized form of stimulus-response compatibility? Dissociating imitative and spatial compatibilities.

In recent years research on automatic imitation has received considerable attention because it represents an experimental platform for investigating a number of interrelated theories suggesting that the perception of action automatically activates corresponding motor programs. A key debate within this research centers on whether automatic imitation is any different than other long-term S-R associations, such as spatial stimulus-response compatibility. One approach to resolving this issue is to examine whether automatic imitation shows similar response characteristics as other classes of stimulus-response compatibility. This hypothesis was tested by comparing imitative and spatial compatibility effects with a two alternative forced-choice stimulus-response compatibility paradigm. The stimulus on each trial was a left or right hand with either the index or middle finger tapping down. Speeded responses were performed with the index or middle finger of the right hand in response to the identity or the left-right spatial position of the stimulus finger. Two different tasks were administered: one that involved responding to the stimulus (S-R) and one that involved responding to the opposite stimulus (OS-R; i.e., the one not presented on that trial). Based on previous research and a connectionist model, we predicted standard compatibility effects for both spatial and imitative compatibility in the S-R task, and a reverse compatibility effect for spatial compatibility, but not for imitative compatibility, in the OS-R task. The results from the mean response times, mean percentage of errors, and response time distributions all converged to support these predictions. A second noteworthy result was that the recoding of the finger identity in the OS-R task required significantly more time than the recoding of the left-right spatial position, but the encoding time for the two stimuli in the S-R task was equivalent. In sum, this evidence suggests that the processing of spatial and imitative compatibility is dissociable with regard to two different processes in dual processing models of stimulus-response compatibility.

Child proportional scaling: is 1/3=2/6=3/9=4/12?

The current experiments examined the role of scale factor in children's proportional reasoning. Experiment 1 used a choice task and Experiment 2 used a production task to examine the abilities of kindergartners through fourth-graders to match equivalent, visually depicted proportional relations. The findings of both experiments show that accuracy decreased as the scaling magnitude between the equivalent proportions increased. In addition, children's errors showed that the cost of scaling proportional relations is symmetrical for problems that involve scaling up and scaling down. These findings indicate that scaling has a cognitive cost that results in decreasing performance with increasing scaling magnitude. These scale factor effects are consistent with children's use of intuitive strategies to solve proportional reasoning problems that may be important in scaffolding more formal mathematical understanding of proportional relations.

Infants' understanding of actions performed by mechanical devices.

Recent research suggests that 9-month-old infants tested in a modified version of the A-not-B search task covertly imitate actions performed by the experimenter. The current study examines whether infants also simulate actions performed by mechanical devices, and whether this varies with whether or not they have been familiarized with the devices and their function. In Experiment 1, infants observed hiding and retrieving actions performed by a pair of mechanical claws on the A-trials, and then searched for the hidden toy on the B-trial. In Experiment 2, infants were first familiarized with the experimenter and the claws but not their function. In Experiment 3, infants were familiarized with the function of the claws. The results revealed that search errors were at chance levels in Experiments 1 and 2, but a significant proportion of the infants showed the A-not-B error in Experiment 3. These results suggest that 9-month-old infants are less likely to simulate observed actions performed by mechanical devices than by human agents, unless they are familiarized with the function of the devices so that their actions are perceived as goal-directed.