Introducing a weanling to new environments and experiences during its first year is one of the most effective investments in its future trainability, because exposure to novelty during the juvenile period produces a horse that approaches unfamiliar situations with curiosity and confidence rather than fear and avoidance. The neurological and behavioral science underlying this is well established: young mammals that experience controlled, positive exposure to novelty during sensitive periods of development become significantly more resilient adults.
The key word is controlled — novel experiences should be introduced at an intensity that produces curiosity rather than fear. Walking a weanling past farm equipment, into different arenas and buildings, past flags and tarps, through puddles, and over different ground surfaces should all happen at the weanling's own pace, with the handler providing calm leadership and allowing the foal to stop, investigate, and retreat slightly before being encouraged forward again. Forcing a weanling through a terrifying stimulus produces sensitization — increased fear response — rather than desensitization.
Public environments — shows, clinics, areas with crowds and loudspeaker noise — can be introduced during the weanling year as observation experiences rather than performance demands. Hauling the foal to a showground simply to stand and watch, with no training agenda, builds exposure to the sights and sounds of competition environments that will pay dividends when the horse is asked to perform in similar environments as an adult.
The weanling that has been systematically exposed to a wide variety of environments, sounds, surfaces, and situations by the end of its first year approaches its first training experiences with a reservoir of confidence and adaptability that makes everything else easier.