z -axis z -score transformation z score z test z transformation zaar zaleplon zar (zaar) Zarontin Zeigarnik effect Zeitgeber Zeitgeist Zelen’s design zelotypia Zen Buddhism Zen therapy Zener cards Zeno’s paradoxes zero-delay matching to sample zero-order correlation zero-sum game zest ZIFT zimbo zinc ZIOF Zipf’s law ziprasidone zoanthropy ZOF Zofran Zöllner illusion Zoloft zolpidem zombie zombie argument zone of comparison test zone of optimal functioning (ZOF) zone of potentiality zone of proximal development zonules zoo- zooerasty (zooerastia) zoolagnia zoom-lens model of attention zoomorphism zoopharmacognosy zoophilia zoosadism Zuckerman Sensation-Seeking Scale zuclopenthixol Zugunruhe Zung Self-Rating Depression Scale (SDS) Zurich School Zwaardemaker olfactometer Zwaardemaker smell system Zyban Zydis zygomaticus zygote zygote intrafallopian transfer (ZIFT) Zyprexa