A common challenge when running psychological studies is getting enough participants. Of course, there are many general strategies for recruiting participants, but I was specifically interested in forums and web pages that are specifically designed for posting links about online psychological studies.
For a given forum, are there any rules about what can be posted? is there any indication of the likely response rate?
The social psychology network has a page for posting online social psychology studies. There are a range of requirements. In particular, it needs to be closely related to social or personality psychology.
SampleSize Subreddit is a community dedicated to completing surveys. They like it when results will be provided at study completion. It has close to 10,000 subscribers at time of posting. I have also seen posts to other subreddits such as the psych subreddit. However, such forums do not always react positively to such postings. If there is particular alignment between the topic and the reddit forum, then there is more likely to be a positive response.
Psychology Research on the Net is a site maintained by Dr John H. Krantz at Hanover College. It lists a lot of different studies.
Online Psychology Research UK contains several hundred studies and is maintained by Dr Kathryn Gardner from University of Central Lancashire.
PsychStudies is maintained by Andrew Thomas from Swansea University.
Psych Forums has a section for posting studies to a section of their forum. However, they do require some form of payment for posting.
In Germany, most students and many researchers conduct their online surveys using the portals soscisurvey.de and unipark.info. Soscisurvey.de includes a so-called "panel", a pool of currently more than 100.000 persons interested in partaking in surveys. To use the panel, you do not have to host your survey on soscisurvey.de, but you must apply a month in advance and comply with the conditions for use (the panel and its members are German). There is an English language conference poster describing the panel.
I know that this answer is restricted to Germany, but maybe something similar exists for other countries and it will give you an idea for your search.
After I had finished writing my master's thesis in 2015, I decided to (try to) tackle the problem of small sample sizes with a new approach. The goal was to develop a website that allows everyone to post their empirical study (online survey or experiment) and to find additional participants based on the principle of voluntary and fair mutual support.
The project has turned into a small start-up called SurveyCircle and the website www.surveycircle.com. The platform was recently launched in 9 English speaking countries. The usage is free and you can see all current studies without even signing up.
This depends heavily on what sort of study you are trying to do, but I know of a number of cognitive science and computational linguistics studies in the past several years that have used Amazon's Mechanical Turk to run subjects online.
As an example from behavioral economics, see Paolacci, Chandler, and Ipeirotis, "Running experiments on Mechanical Turk", Judgment and Decision Making, vol 5, no 5, 2010: http://repub.eur.nl/res/pub/31983/jdm10630a%255B1%255D.pdf
Psych Forums has a section for posting studies to a section of their forum. However, they do require some form of payment for posting.
In fact it's not exact. As explained here : http://www.psychforums.com/surveys-studies/topic44450.html if you are a "professor/researcher/student in a university/college/institute/faculty of psychology" it's entirely free and you get your links somehow included in specific forums so you have exact targeted audience for your studies.
Note that psych forums has more than 125'000 members, hundreds of forums and gets about 40'000 visitors a day so it's kind of ideal if you have any research to achieve.
In my opinion, Psychforums.com is by far the best place to post online studies, but your school/university needs to establish a partnership with them first. Best is to speak with your professor or someone responsible for your Psychology department in order to have that partnership in place, which is in fact really easy (see the post before). Once done, all the students/researchers/professors of your school will be able to post there, so it's not on a per-study basis. Also, your study can be exposed in 3 specific forums.
The problem with the other places is that it's focusing on online studies, so only people searching specifically for online studies will found them, and you also only get participants interested in cash reward, which I suspect change results, as it drags in people that might not be interested in your online study at all. On Psychforums you can have very specific targeted audience as well as a very general audience depending on which forum you ask to be exposed to, and those participants are not coming to Psychforums initially to participate in a study. Of course it depends on your study, but in my personal experience, I got more than 50 participants in a week, while all the other places I've posted brought me less than 5 participants.
A relatively new site for subject recruitment online is Prolific Academic. It is a Mechanical Turk competitor targeted at the academic market. It offers some features that mturk doesn't that may be useful for researchers, such as more in depth pre-screening and demographics information. A potential negative of the site is that they currently require a minimum payment rate of $7.50/hour, which is more expensive than the typical Turk rate.
