Infants' Awareness of Number: Innate Ability or Perceptual Bias?

Infants' Awareness of Number: Innate Ability or Perceptual Bias?

Jessica Sparks

07.09.2021

In order to identify the origin of our understanding of numerosity and arithmetic abilities, it is essential that such abilities are measured in infants. In Wynn’s (1992) study, a case was made for an innate ability to perform arithmetic operation on small number sets as it was demonstrated that infants would look longer at displays that violated their expectations of number. However, research in the years following this seminal study cast doubt on this interpretation of infants’ behaviour. Other research has suggested that perceptual biases are at play, rather than infants possessing a symbolic understanding of number. To address the contrasting finding in this area of developmental research, this study set out to analyse preexisting data to investigate the factors that influence infants’ abilities to track objects over occlusion and to identify the most appropriate level of interpretation of this ability The present study recruited a sample of 32 infants across two experiments. Adapting the methodology from Wynn (1992), Experiment 1 measured looking time when an object was revealed to be missing from the display, violating infants’ expectation of presence. Experiment 2 measured looking time when an object was revealed to be in the incorrect position on the stage, violating infants’ expectation of position. It was found that infants violation trial had a significant effect on looking time and whether the object missing was the first or last to be placed had a significant effect on looking time in violation of presence conditions

Addition, subtraction, Number, Object Tracking, object files, Infant perception

Participants:
In this study, participants were 32 infants aged 5- to 7-months, (M = 188.38 days, SD = 10.51, range = 175 – 218). Infants were 15 males and 17 females. 16 participants were used in each experiment. In Experiment 1, participants were 7 males and 9. In Experiment 2, participants were 8 males and 8 females. Participants in each experiment were matched based on age.
Apparatus & Stimuli:
The experiment took place in a dimly lit test room, with displays presented on a grey stage measuring 64cm wide by 40cm high and 31cm deep. An 8.5cm high black screen located 31.5cm behind the front of the stage was used to occlude the display by being rotated upwards. The display also consisted of a 30cm rotating platform that allowed different configurations of objects to be rotated rapidly. The objects used in this study were two 12.5cm high by 9.5cm wide toy hedgehogs that squeaked when squeezed. These toys were magnetic at the bottom.
Procedure:
Infants were sat in either a high seat or on a caregiver’s lap, 60cm from the front edge of the stage. In cases where infants were sat on a caregiver’s lap, the caregiver’s eyes were above the stage as to avoid them seeing the display and possibly influencing the infant’s behaviour. After gaze calibration to ensure the accuracy of eye-tracking measures, the procedure closely followed that of Wynn (1992) and Bremner et al (2017).
Three pre-test (baseline) trials were presented initially. These resulted in the correct outcome of the operation as well as the two incorrect outcomes in counterbalanced order. The screen was lowered to reveal either one or two toys, depending on the trial, and the observer recorded where the infant looked on the stage. In terms of the location of the toys in trials, when one was presented, it was placed 7.5cm to the right of the stage’s centre. When two toys were presented, the second toy was placed 7.5cm to the left of the stage’s centre. Pre-test trials continued until the infant accumulated at least 2 seconds of looking time and looked away from the display for seconds or more. When this was achieved, the screen was raised and the same procedure was repeated for the displays for the other two outcomes.
Test trials were administered in two blocks of four trials. The experimenter’s hand emerged at one side above the screen. The side at which the toy first appears was counterbalanced across participants. The toy squeaked to capture the infant’s attention and continued to squeak to maintain this attention as it was placed on one of the locations used during the correct outcome familiarisation trial. The experimenter then slowly withdrew their hand, clasping and unclasping the hand to show the infant that it was empty, and the screen was then raised to occlude the toy from the infant’s view. The time taken from the appearance of the toy to the withdrawal of the hand took approximately 5 seconds. The experimenter’s hand then reappeared above the screen from the opposite side of the display, holding an identical squeaking toy. Once the infant’s attention had been captures, the toy was placed in the other location used during correct outcome familiarisation trials. The hand was then raised and, again, clasped and unclasped to show the infant the hand was empty. The hand as then slowly withdrawn from the display. The screen was then lowered to reveal either the correct or incorrect outcome.
In Experiment 1, conditions involved violation of object presence. In ‘added object absent’ trials, the screen was lowered to reveal the last object to be placed was missing from the display. In ‘original object absent’ trials, the screen was lowered to reveal the first object to be placed, present before the screen was raised, was missing from the display. In Experiment 2, conditions involved violation of object position. In ‘added object in wrong location’ trials, the screen was lowered to reveal the last object to be placed appeared in the centre of the stage rather than on the side of the stage in which it was placed. In ‘original object in wrong location’ trials, the screen was lowered to reveal the original object in the display appeared in the centre of the stage rather than on the side it was in before the screen was raised.
These test trials continued until the infant had accumulated at least 2 seconds of looking tie and looked away from the display for 2 seconds or more.

Lancaster University

.csv

Sparks2021

Julonna Peterson and Rebecca Mitchell

open

Wynn's 1992 study

English

Data

Developmental

Gavin Bremner

MSC

Developmental

32

ANOVA