Aphantasia defined as VVIQ score of 16 indicating zero visual imagery. Hypophantasia defined as VVIQ 17-32 for vague dim images. Typical imagery VVIQ 33-74 in 89.7% of 9,063 participants. Hyperphantasia VVIQ 75-80 in 6.1% with images as vivid as vision. Study 1 on 3,049 international participants yields 1.2% aphantasia, 3% hypophantasia, 5.9% hyperphantasia. No significant link between imagery ability and gender. No significant link between imagery ability and education level. No significant link between imagery ability and continent of nationality. Weak positive correlation between age and VVIQ score. VVIQ shows excellent reliability with Cronbach's alpha 0.926. Combined data from three studies confirms consistent prevalences. 4.2% total have aphantasia or hypophantasia. Recruitment avoided imagery terms to prevent bias. Sample spans 85 nationalities mostly university-educated. Aphantasia linked to neurophysiological differences like weaker brain connectivity. Hyperphantasia shows stronger prefrontal-visual network links. Lower imagery protects against intrusive trauma memories. Aphantasia may favor scientific careers, hyperphantasia artistic ones.