Table 1.

Children: tests on behaviour, motor development, language skills, intelligence

Questionnaires	Parameter	Positive β indicates more or better	Age of child
Bayley mental scale [21] Bayley motor scale [21]	Visual and auditory discernment, eye-hand coordination, imitation, language development, memory and problem solving capacity. Mean score for the general population of 100 (± SD 15). Motor development. Mean score for the general population of 100 (± SD 15).	Cognitive development Motor development	36 months
Infant Behaviour Questionnaire (IBQ) [22]: Temperament as observed by the mother	Scale 1 = stress and latency to approach sudden or novel stimuli Scale 2 = smiling and laughter Scale 3 = distress to limitations Scale 4 = activity level Scale 5 = duration of orienting	Fear responses. Smiling or laughter from the child in general caretaking and play situations. Persistence and goal oriented behaviour. Gross motor activity: movement of arms and legs, squirming and locomotor activity. Habituation: more attention to and/or interaction with a single object for extended periods of time.	12 months
Milestones: developmental abilities	1 = grasping 2 = rolling over 3 = sitting up 4 = crawling 5 = first steps alone	Time needed to achieve the milestone: Grasping and picking up objects. Learning to flip over from his back to his tummy and vice versa. To sit up without support. Crawling. First steps alone unaided (first steps alone).	0–36 months
Tests	Measurement type	Positive β indicates a higher capacity in terms of	Age of child
Reynell Language Developmental Scale (RTOS): receptive language development level measured by oral instructions to carry out small tasks while playing with toys [23].	Verbal comprehension scale	Receptive language development.	36 months
Snijders-Oomen non-verbal intelligence test (SON 2.5–7), [24]: Intelligence: reasoning and visuospatial abilities	Three intelligence quotients (IQ) can be calculated with this intelligence tests with a mean score for the general population of 100 (± SD 15) Total intelligence scale: SON-IQ Performance Scale (PS) IQ Reasoning Scale (RS) IQ	(Nonverbal) intelligence (IQ). Performance IQ: better in making puzzles, mosaics and patterns. Reasoning IQ: better in categories, situations and analogies.	36 months
Observation of toy preference: 7 min. Lasting observation of masculine/feminine play behaviour [25, 26]	Masculine play behaviour Feminine play behaviour Non-gender specific play behaviour Switching attention	Time playing with masculine toys: little cars, fire truck, construction blocks, toy gun. Time playing with feminine toys: little dolls, hair doll, baby doll, kitchen accessories. Time playing with non-gender specific toys: puzzle, book The number of times the child switches between toys.	36 months
NES 3 (Neurobehavioral Evaluation System) [27]	Continuous Performance Test	Computerised vigilance task adapted according to Patandin et al., [28].	36 months