Recently, this section featured an article about the tarantula Typhochlaena costae. While the piece was very interesting, this was likely lost on some readers, as it's difficult to focus on details while distracted by the sound of your own screaming.

Arachnophobia is one of the more well-known phobias and can be very potent. Searching the science section for some lunchtime reading is not the sort of activity that typically includes spiders, so to be suddenly confronted, apropos of nothing, by an image of a humungous tarantula probably caught many unawares. How many tablets/phones/laptops were ruined due to being hurled across the room in a panic?

Most would consider this an overreaction. Granted, there are many dangerous species of spider (I'd link to examples but can't find any without pictures, and I'm not a hypocrite) but the odds of encountering one are, in the UK at least, vanishingly small. And even then, the biggest spider is physically no match for a person; a rolled up newspaper is not considered a lethal weapon among humans. Arachnophobes substantially outnumber people who have been genuinely injured by spiders, and yet the irrational fear of spiders is commonplace.

What scares people often makes little logical sense. As I do stand-up comedy on occasion, I'm regularly told I'm "incredibly brave", yet all I'm doing is saying words in front of people. The people who tell me I'm brave think nothing of driving, an often fatal practice. But when you do genuinely fear something for no rational reason, then you may have a phobia.

Phobias are psychologically interesting. There are three possible types: specific phobias, social phobias and agoraphobia. Agoraphobia isn't just a fear of open spaces; it describes a fear of any situation where escape would be difficult and/or help wouldn't be forthcoming. The fact that most such situations occur outside the sufferer's home results in them not going out much, which is probably where the "open spaces" confusion comes from.

Specific phobias are probably the most recognised. Specific phobias are an irrational fear of a specific thing or situation. Specific phobias can be further subdivided into situational (eg claustrophobia), natural environment (eg acrophobia), animal (eg the aforementioned arachnophobia) or blood-injection-injury types (eg … blood and injections, I guess). You could still have a phobia which doesn't fit any of these descriptors though. Maybe you've got an irrational fear of being categorised? If so, sorry.

Social phobias are where you have an irrational fear of how people will react to you in a situation. The fear of rejection or judgement from others is a powerful force for humans; much of how we think and behave is calibrated around the views and behaviours of others. There's a whole discipline about it. People value the views of others differently of course. One way to reduce the value you place on the opinions of strangers is to read the comments on the internet. Any comments, anywhere.

How do we even develop a fear that is by definition irrational? One explanation is classical conditioning; you experience something bad involving a thing, you associate the bad experience with that thing, then you become afraid of that thing. But clever humans can also learn by observation; you see your mother panicking frantically in response to a wasp when you're a child, you'll likely be afraid of wasps too.

If we are given enough (possibly inaccurate) information, we may just "figure out" things are scary via instructional fear acquisition. Certain horror films are particularly good at this, presenting everyday things like birds as things to be feared, associations which stay with people for a long time. The Final Destination series is particularly cruel in that it tries to make people terrified of "not dying". We may even have evolved to acquire some phobias. Research has shown that primates tend to learn to fear snakes very quickly when compared to other stimuli. If you're evolving in an environment where snakes are a genuine but subtle threat, this tendency would help no doubt. It might explain the spider thing too.

Not so sure about aerophobia though, we probably didn't need to worry about that on the African Savannah

What can you do about this? It's not like those with phobias aren't aware of them. One of the criteria in the DSM-IV for diagnosing phobias is that the sufferer is aware of the irrational nature of their fear. There are a lot of brain regions involved, like the insular cortex and amygdala. And you can't simply make someone encounter the thing they're afraid of to show them it's harmless. As far as the brain is concerned, the fear response IS a negative physical consequence, so on a subconscious level the phobia is self-fulfilling.

There are methods of treating phobias if they're genuinely debilitating. Systematic desensitisation is one approach (where the source of the phobia is introduced in easily-managed stages), cognitive behavioural therapy, even antidepressants if all else fails.

It's different if you're talking about things like homophobia or Islamophobia, as often these are more likely to be misleadingly named prejudices than genuine phobias. There are fewer options for treating these though; science has tackled many psychological conditions, but there's still no known cure for being a dick.

Dean Burnett encourages you not to be afraid and follow him on Twitter @garwboy

Or, check out the podcast Dean and Dave's Science Webnoise, with friend and fellow science-blogger Dave Steele