What type of hypothesis predicts no significant difference?

The null hypothesis is a fundamental concept in statistics, particularly in hypothesis testing. It is formulated to propose that there is no significant difference or effect observed in the variables being studied. By stating that any observed differences are due to chance or random variation rather than a true effect, the null hypothesis serves as a baseline against which researchers compare their experimental results.

In the context of psychological research or any scientific investigation, the null hypothesis allows researchers to perform statistical tests to determine if their findings provide enough evidence to reject it in favor of the alternative hypothesis, which suggests that there is a significant difference or effect. Thus, the null hypothesis is essential for ensuring that any conclusions drawn from the research are statistically valid and not merely due to variability inherent in the data.

Other types of hypotheses, such as directional and alternative hypotheses, posit the existence of differences or effects, which is contrary to the null hypothesis's premise of no difference. An extraneous hypothesis is not a standard term used in hypothesis testing and generally refers to variables that might influence the outcome but are not the focus of the study.

Therefore, the correct option predicting no significant difference is indeed the null hypothesis.