Rugani, Rosa and Regolin, Lucia and Macchinizzi, Matteo and Zhang, Yujia (2024) Hatching with Numbers: How Pre-natal Experience Affects Chicks' Left-to-Right Mental Number Line. [Data Collection]
Collection description
The present study aims to explore the role of brain lateralization in Space-number association by testing newborn domestic chicks (Gallus gallus) in an ordinal task. Domestic chicks offer the possibility to manipulate the degree of brain lateralization through light exposure during the last period of incubation: light-incubated chicks are strongly lateralized, and dark-incubated chicks are weakly lateralized brains. In two experiments, 100 male chicks were trained to select the fourth element in a series of 10 identical elements. In each experiment, a group of strongly lateralized chicks and a group of weakly lateralized chicks underwent sagittal and three fronto-parallel tests (one in binocular condition and two in monocular conditions). At test, in Experiment 1, both spatial and numerical cues were available by having constant inter-element distance; in Experiment 2, spatial cues were excluded by altering inter-element distance in each trial. In experiment 1, hatch conditions significantly affected the sagittal test: a higher degree of lateralization led to a higher accuracy. In the fronto-parallel left and right tests, there was a main effect of hatch condition and side preference, with interactions showing stronger side biases in light-hatched chicks. In experiment 2, the degree of lateralization did not influence the accuracy and leftward bias in the sagittal test or in the fronto-parallel binocular test. In the fronto-parallel left and right tests, side preferences remained, with an interaction in the fronto-parallel right test showing a right bias only in light-hatched chicks. The results indicate that the degree of hemispheric lateralization affects performance in ordinal tasks when both spatial and numerical cues are relevant. In contrast, pre-hatching light stimulation did not affect chicks' performance on purely ordinal information processing. These findings suggest that brain lateralization and spatial cues in the environment jointly contribute to the directional SNA.
10.25430/researchdata.cab.unipd.it.00001424
orcid.org/0000-0001-5294-6306
