Logical Captcha takes advantage of the TextCaptcha.com service, which provides logic-based textual questions instead of distorted images or audio to validate that the entity registering is a real live human being, and not a spam bot. It will provide protection against false registrations and the dreaded spam comments, etc.
An example of such a question might be:
Question: 
Out of a truck, a lion, the color purple, and the number forty-two, which has a door?
Answer: 
truck
Textual logic-based captchas mean that your registration process will be accessible to everyone, including visually/hearing impaired visitors who use access technology to surf the web. It requires a free API key from <a href="http://TextCaptcha.com" rel="nofollow ugc">TextCaptcha.com</a>
This plugin was developed by Josh de Lioncourt of <a href="http://maccessibility.net" rel="nofollow ugc">the Mac-cessibility Network</a>, a site dedicated to blind and visually impaired users of the Mac OS X operating system, the iPhone OS, and other Apple Inc. products and services. Josh de Lioncourt, the Mac-cessibility Network, and related sites are not in anyway affiliated with TextCaptcha.com

Logical Captcha

Integrates a logic captcha to verify that the registrant is a human and not a spam bot instead of using distorted images or audio.

webvitaly

<ul>
<li><a href="http://web-profile.net/wordpress/plugins/security-protection/" title="Security-Protection" rel="nofollow ugc">Security-Protection</a></li>
<li><a href="http://web-profile.net/donate/" title="Donate" rel="nofollow ugc">Donate</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/" title="WordPress plugins" rel="nofollow ugc">WordPress plugins</a></li>
</ul>
Why humans should prove that they are humans by filling captchas? Lets bots prove that they are not bots with adding javascript to their user-agents!
Security-Protection blocks and stops brute-force attacks. 
<a href="https://wordpress.org/plugins/security-protection/faq/" rel="ugc">Want to read more how Security-Protection plugin works</a>?
<ul>
<li>no captcha, because brute-force attacks is not users’ problem</li>
<li>no options, because it is great to forget about brute-force attacks completely</li>
</ul>
Plugin is easy to use: just install it and it just works.
Important: delete ‘admin’ username if you have it on your site. More than 90% of brute-force attacks try to crack the ‘admin’ username.
Few of the most commonly used and worst passwords. Do not use them or similar:
<ul>
<li>123456</li>
<li>p@s$w0rd</li>
<li>qwerty</li>
<li>qwe123</li>
<li>admin123</li>
<li>iloveyou</li>
<li>letmein</li>
</ul>
<h4>Useful:</h4>
<ul>
<li><a href="https://wordpress.org/plugins/page-list/" title="list of pages with shortcodes" rel="ugc">“Page-list” – show list of pages with shortcodes</a></li>
<li><a href="https://wordpress.org/plugins/iframe/" title="embed content" rel="ugc">“Iframe” – embed content</a></li>
<li><a href="http://web-profile.net/wordpress/plugins/" title="WordPress Pro plugins" rel="nofollow ugc">WordPress Pro plugins</a></li>
</ul>

Security-Protection

Protection from login, registration and reset-password brute-force attacks. No captcha.

Logical Captcha vs Security-Protection