An observational study in Health Adults, sponsored by Nigde Omer Halisdemir University. Recruiting at 1 site in Turkey (Türkiye). Open to participants aged 18 Years to 40 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2026-10-09.
Sponsored by Nigde Omer Halisdemir University · Observational
Due to the difficulties and risks of directly measuring prenatal hormone levels, biomarkers that indirectly reflect this exposure are used in research. In this context, the ratio of second to fourth finger length (2D:4D) is widely preferred because it is an easily applicable and non-invasive measurement. Evidence shows that 2D:4D stabilizes from the second trimester of pregnancy onward and exhibits strong sex differences across populations. The 2D:4D ratio is generally lower in men than in women. 2D is more strongly influenced by prenatal estrogen, while 4D is more strongly influenced by prenatal testosterone; this occurs during the first trimester of intrauterine fetal development. To our knowledge, studies examining the relationship between the 2D:4D ratio, an indirect indicator of prenatal androgen exposure, and dexterity and tactile discrimination are limited. Accordingly, the planned study aims to evaluate the relationship between the 2D:4D ratio and fine motor skills and tactile discrimination in healthy young adults.
Sex hormones experienced during prenatal exposure play a significant role in shaping certain lifelong characteristics by influencing both the physical and neurological development of individuals. The effects of these hormones, particularly on the developing nervous system, contribute to the emergence of behavioral and functional differences. Hand preference and certain behavioral traits in humans have been shown to be related to prenatal hormonal exposure. However, the development of these traits is not limited to hormonal influences alone, but is shaped by the interaction of genetic, environmental, and sociocultural factors. Due to the difficulties and risks of directly measuring prenatal hormone levels, biomarkers that indirectly reflect this exposure are used in research. In this context, the ratio of second to fourth finger length (2D:4D) is widely preferred because it is an easily applicable and non-invasive measurement. The 2D:4D ratio is generally lower in men than in women. 2D is more strongly influenced by prenatal estrogen, while 4D is more strongly influenced by prenatal testosterone; this occurs during the first trimester of intrauterine fetal development. However, whether the 2D:4D ratio is a reliable indicator of prenatal hormonal exposure is still a controversial issue in the literature. Therefore, examining the relationship between the 2D:4D ratio and various biological and functional characteristics remains important. To our knowledge, studies examining the relationship between the 2D:4D ratio, an indirect indicator of prenatal androgen exposure, and dexterity and tactile discrimination are limited. Accordingly, the planned study aims to evaluate the relationship between the 2D:4D ratio and fine motor skills and tactile discrimination in healthy young adults. It is hypothesized that prenatal hormonal exposure may indirectly shape finger morphology and receptor distribution by affecting skin and nervous system development, which may be a determining factor in tactile sensitivity and dexterity.
Nigde Omer Halisdemir University is the lead sponsor of 93 studies on the registry; 31 are open to participants now.
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- Healthy individuals aged 18-40
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Young and healthy adults aged 18-40
Other: Digit Ratio · Behavioral: Fine motor skills · Behavioral: Tactile Discrimination
The second (2D) and fourth (4D) finger lengths of the participants will be measured separately in both hands by a physiotherapist with over thirteen years of clinical experience.
Hand dexterity will be assessed using the Purdue Pegboard Test. The test will be administered according to standard procedure with participants seated at a table. Participants will be asked to place the pegs into the corresponding holes as quickly and accurately as possible within a specified time (30 seconds).
To perform the 2-point discrimination tests, the Baseline® two-point discriminator will be used. Measurements will be applied to the distal phalangeal pulp of the index finger on both hands while participants are seated in a comfortable position with their eyes closed.
2-point discrimination test
To perform 2-point discrimination tests, the Baseline® two-point discriminator will be used. Measurements will be applied to the distal phalangeal pulp of the index finger on both hands while participants are seated in a comfortable position with their eyes closed. The test will begin at a distance of 8 mm, allowing participants to perceive the stimulus as two points, and then the distance will be gradually reduced. After 5 mm, measurements will continue at 1 mm intervals. In each application, both contact points will be applied to the skin simultaneously and with equal pressure, and participants will be asked to indicate whether the perceived stimulus is a single point or two points.
Time frame: 12 months
Digit Ratio
Measurements will be taken after participants' hands are placed on a flat surface with palms facing upwards. Finger length is defined as the distance from the midpoint of the proximal crease line where the finger joins the palm to the distal point of the fingertip. Measurements will be performed using a digital caliper with 0.01 mm accuracy, two separate measurements will be taken for each finger, and the average value will be recorded. Based on the obtained measurements, the 2D:4D finger ratio will be calculated by dividing the 2D length by the 4D length in both hands .
Time frame: 12 months
Fine motor skills
The test will be administered according to standard procedure while participants are seated at a table. Participants will be asked to place the pegs into the corresponding holes as quickly and accurately as possible within the specified time (30 seconds). In the dominant and non-dominant hand tests, participants will be asked to place pegs with one hand for 30 seconds, while in the both-hand test, the simultaneous use of both hands will be evaluated. The number of correctly placed pegs for each subtest will be recorded, and higher scores will be considered as better fine motor skill performance.
Time frame: 12 months
Plan to share: No
Started Oct 2026 (actual). Primary completion is estimated for Jul 2027, 8 months after the start.
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Nigde Omer Halisdemir University