Effects of d-amphetamine on self-aggression and posturing in stumptail macaques.

Scientists gave stumptail macaques tiny shots of d-amphetamine. The doses ranged from 0.01 to 0.3 mg/kg.

They watched each monkey before and after the drug. They counted self-biting, head-hitting, and odd frozen poses.

The drug only mattered for animals that already hurt themselves or posed. Low doses raised self-biting a little; high doses brought it back down.

Strange poses grew steadily with every higher dose. Monkeys that never self-bit stayed calm the whole time.

Sobsey et al. (1983) used the same drug and dose range in pigeons. They saw the opposite: key-pecking stopped when colors predicted the drug. Same chemical, opposite direction.

Haring et al. (1988) tested thioridazine in adults with ID. Like here, only people who already showed lots of stereotypy improved. Baseline behavior again predicted who responded.

Stretch et al. (1966) gave rats methylphenidate. High doses wrecked stimulus control but still cut shocks. Together the papers say: stimulant dose and starting behavior both shape the final picture.

If you track self-injury or stereotypy, note the baseline first. A drug or intervention may only ‘work’ in the clients who already show the problem. Before adding or changing meds, graph each person’s pre-treatment levels. That single step keeps you from labeling a helper ‘ineffective’ when it simply had no room to act.