The penile plethysmograph and the vaginal photometer measure physiological events directly related to sexual arousal, but they do not measure sexual arousal itself. Instead, these tools are said to offer reflections of a hypothetical construct called "sexual arousal." Using this example, explain the following terms: hypothetical construct, construct validity, and operational definition.

What will be an ideal response?

A hypothetical construct is a theoretical idea that refers to something that can't be observed directly. For example, arousal involves a subjective feeling of being aroused, which cannot be directly observed. In order to use such an idea scientifically, it must be defined in terms of observable indicators, even if these indicators do not define the idea completely. These observable indicators are the operational definition. In the case of arousal, observable factors such as penile circumference and vaginal engorgement are used as indicators of arousal. If these indicators turn out to be related to other indicators of arousal, such as the person's subjective report, then the indicators are said to have construct validity. This means that they are thought to be valid, if incomplete, indicators of the hypothetical construct.