Higher Maths for Cognitive Science

Hi everyone! I am a BA Psychology student (University at Buffalo) at an external campus in Singapore, which means I don't have a lot of options for my electives. I am very keen on continuing my academic journey towards cognitive science, and I would like to study higher level mathematics independently before going to graduate school. My current level is calculus 1 and I'd appreciate your suggestions (textbooks, strategies, etc.,) on how to climb up the math ladder higher. I would also like to know which area of maths I should explore if I were to take CS courses in the future. Thanks!

If your major is in psychology, then sooner or later you're going to be needing some statistics - especially for the experimental side of the subject. Preparatory for statistics would be more calculus and some linear algebra.