Hockenbury Discovering Psychology 5th txtbk

198 CHAPTER 5 LearningIN FOCUSEvolution, Biological Preparedness, and Conditioned Fears: What Gives You the Creeps?Do these photographs make you somewhat uncomfortable?A phobia is an extreme, irrational fear of a specific object,animal, or situation. It was once believed that all phobias wereacquired through classical conditioning, as was Little Albert’sfear of the rat and other furry objects. But many people developphobias without having experienced a traumatic event in associationwith the object of their fear (Merckelbach & others, 1992).Obviously, other forms of learning, such as observational learning,are involved in the development of some fears (Olsson &Phelps, 2007).When people do develop conditioned fears as a result of traumaticevents, they are more likely to associate fear with certainstimuli rather than others. Erv, not surprisingly, has acquired aconditioned fear response to the “killer attic.” But why doesn’tErv shudder every time he hears a lawn mower or sees a ladder,the clothes he was wearing when he got trapped, or his can ofoil?Psychologist Martin Seligman (1971) noticed that phobiasseem to be quite selective. Extreme, irrational fears of snakes,spiders, heights, and small enclosed places (like Erv and Fern’s attic)are relatively common. But very few people have phobias ofstairs, ladders, electrical outlets or appliances, or sharp objects,even though these things are far more likely to be associatedwith accidents or traumatic experiences.Seligman proposed that humans are biologically prepared todevelop fears of objects or situations—such as snakes,spiders, and heights—that may once have posed athreat to humans’ evolutionary ancestors. AsSeligman (1971) put it, “The great majorityof phobias are about objects ofnatural importance to the survival ofthe species.” According to this view,people don’t commonly develop phobias ofknives, stoves, or cars because they’re not biologically preparedto do so.Support for this view is provided by early studies that tried toreplicate Watson’s Little Albert research. Elsie Bregman (1934)was unable to produce a conditioned fear response to woodenblocks and curtains, although she followed Watson’s procedurecarefully. And Horace English (1929) was unable to produce aconditioned fear of a wooden duck. Perhaps we’re more biologicallyprepared to learn a fear of furry animals than of woodenducks, blocks, or curtains!More recently, psychologists Arne Öhman and Susan Mineka(2001, 2003) have accumulated experimental evidence thatsupports an evolutionary explanation for the most commonphobias, especially fear of snakes. For example, people seem tobe biologically prepared to rapidly detect snakes. One studyinvolved having people look at groups of photographs of naturalstimuli like flowers or snakes. Participants were faster atspotting a single snake image among photos of flowers thanthey were at detecting a flower image among photos of snakes.Other research has shown that people more readily acquire conditionedfear responses to pictures of snakes that have beenpaired with electric shock than to pictures of mushrooms andflowers that have been paired with electric shock. These resultssuggest that people are biologically prepared to easily acquirefears of snakes.However, these studies have been conducted in adults, raisingthe question that the response to snake images might be due toaccumulated knowledge about snakes. But Vanessa LoBue andJudy S. DeLoache (2008) showed that 3- to 5-year-olds were alsofaster at spotting a lone snake image among photos of flowers,frogs, or caterpillars than they were at spotting a loneflower, frog, or caterpillar among photos of snakes. This findinglends support to the idea that humans have an innate evolvedability to detect threatening stimuli more quickly than nonthreateningstimuli.Öhman and Mineka (2003) suggest that because poisonoussnakes, reptiles, and insects have been associated with dangerthroughout the evolution of mammals, there is an evolved“fear module” in the brain that is highly sensitizedto such evolutionarily relevant stimuli. Accordingto this explanation, individuals who more rapidlydetected such dangerous animals would have beenmore likely to learn to avoid them and survive toreproduce and pass on their genes to futuregenerations (Öhman & others, 2007). Formore on how evolved brain mechanismsmight be involved in fearful responses,see Chapter 8.When this concept is applied to taste aversions, rats (and people) seem to be biologicallyprepared to associate an illness with a taste rather than with a location, aperson, or an object. Hence, Don developed an aversion to the spaghetti sauce andnot to the fork he had used to eat it. Apparently, both humans and rats are biologicallyprepared to learn taste aversions relatively easily. Thus, taste aversions can beclassically conditioned more readily than can more arbitrary associations, such asthat between a ringing bell and a plate of food.