A file extension is the set of three or four characters at the end of a filename; in this case, .obj. File extensions tell you what type of file it is, and tell Windows what programs can open it. Windows often associates a default program to each file extension, so that when you double-click the file, the program launches automatically.
A threshold (or limen) is the point of intensity at which the participant can just detect the presence of a stimulus (absolute threshold) or the presence of a difference between two stimuli (difference threshold). Stimuli with intensities below the threshold are considered not detectable (hence: sub-liminal). threshold (or limen) is the point of intensity at which the participant can just detect the presence of a stimulus (absolute threshold) or the presence of a difference between two stimuli (difference threshold). Stimuli with intensities below the threshold are considered not detectable (hence: sub-liminal).
Object permanence. Object permanence is the understanding that objects continue to exist even when they cannot be observed. This is a fundamental concept studied in the field of developmental psychology, the subfield of psychology that addresses the development of infants' and children's social and mental capacities. There is not yet scientific consensus on when the understanding of object permanence emerges in human development. Some researchers contend that it is acquired within the first two years of life, while others believe that it is an innate or built-in understanding present at birth.