Key Studies

Approaches: Pavlov’s Dogs Study

Aim: To see if associating a reflex action with a neutral stimulus causes learning to take place, producing a conditioned response.

Procedure: In a controlled environment, Pavlov presented 35 dogs with food, which was an unconditioned stimulus, and salivation was the unconditioned response. He also presented them with the sound of a bell, which is a neutral stimulus, as it garnered no reaction. During the experiment, the bell was paired with the food.

Findings: After conditioning took place, the bell became a conditioned stimulus which caused the conditioned response of salivation from the dogs.

Conclusion: Pavlov discovered the phenomena now known as ‘classical conditioning’.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods increase replicability as well as reliability.

The dogs in the study cannot consent to taking part, making the procedure ethically questionable.

Humans are much more complex than animals, so the results found in this study cannot be generalised to humans.

Approaches: Watson & Rayner’s Little Albert Study

Aim: To find out if classical conditioning works on humans.

Procedure: At 9 months old, Little Albert was tested with stimuli such as a white rat, a rabbit and cotton wool to see if he had a fear reaction, and he didn’t, showing these were neutral stimuli. Watson and Rayner also checked his fear response by banging an iron bar, and Albert cried at the loud noise. This shows the noise was an unconditioned stimulus and the crying was an unconditioned response.

Findings:  At 11 months old, Little Albert was conditioned as a result of being shown the white rat paired with striking the iron bar. When the rat was later presented alone, he whimpered. Over the next few days, Watson and Rayner tested his reaction to the rat and other white furry animals and objects like a rabbit, a dog and Watson wearing a Santa mask - Little Albert showed fear responses.

Conclusion: Watson and Rayner concluded that they had successfully conditioned Little Albert to fear the white rat and that his fear response generalised to other white, furry things.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods increase replicability as well as reliability.

The practical applications for this study are diverse. For example, techniques like flooding (exposing someone to the feared stimuli, letting them experience panic, but then letting the panic reaction wear off) and systematic desensitisation (the patient gets used to pictures of the feared thing, then photographs, then seeing it at a distance, then close up, before handling it).

Little Albert cannot consent to taking part, making the procedure ethically questionable. He also isn’t protected from harm, as Watson and Rayner exposed him to potentially stressful situations that could’ve caused unnecessary distress.

This study was only conducted on one child, so the results cannot be generalised to humans.

Approaches: Skinner’s Rats Study

Aim: To see if positive reinforcement will condition animals to engage in specific behaviours.

Procedure: Skinner placed rats in his ‘Skinner Box’ with a lever that dispensed food. Skinner also placed rats in a different variation of his ‘Skinner Box’, which had a lever that would temporarily stop an electrified floor.

Findings: The rats learned to associate their action of pulling the lever with a reward, which was a food pellet - this is positive reinforcement. The rats also learned to associate their action of pulling the lever with avoiding a negative consequence, which was stopping the pain, but not as fast as the rats that were positively reinforced - this is negative reinforcement. 

Conclusion: Skinner concluded that positive reinforcement shapes behaviour better than negative reinforcement.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods increase replicability as well as reliability.

The practical applications for this study are diverse. For example, Token Economy Programmes (TEPs) (using positive reinforcement to modify behaviour in a closed setting like a school, hospital or prison).

The rats in the study cannot consent to taking part, making the procedure ethically questionable.

Humans are much more complex than animals, so the results found in this study cannot be generalised to humans.

Approaches: Bandura’s Bobo Doll Study

Aim: To investigate the effect of observed aggression on children’s behaviour.

Procedure: Bandura used a matched pairs design where all 72 participants aged 3-6 years old observed either an aggressive model, a passive model or no model.

Findings: Bandura found that children were more likely to act aggressively if they observed an aggressive model. In a separate study, he also found that boys were more likely to imitate behaviour when the model was male too.

Conclusion: Bandura concluded that children learn behaviour by observing others around them.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods increase replicability as well as reliability.

Matched pairs designs control for certain participant variables, increasing the internal validity, although not all participant variables can be controlled. The study also won’t be impacted by order effects because all participants are only taking part in one level of the IV, meaning the chances of demand characteristics skewing the findings are less so.

The children in the study weren’t protected from harm as they were exposed to aggressive behaviour which could cause unecessary distress.

Approaches: Freud’s Little Hans Case Study

Context: Freud studied Little Hans with his Oedipus complex in mind. Little Hans was a 5 year old boy with a phobia of horses with black bits around the mouth and wearing blinkers in particular. When he was 3, Little Hans had an interest in his ‘widdler’ (penis) and feared horses would bite him.

Conclusion: Freud believed that the horse was a symbol for his father - the black bits represented his father's moustache, and the blinkers were his spectacles. Freud also concluded that little Hans feared that horses (his father) would bite (castrate) him as punishment for the incestuous desires he had towards his mother.

Case studies provide rich qualitative data on a specific experience. However, they are idiographic due to having small sample sizes and only focusing on a singular experience.

In this case, Freud worked directly with Little Hans’ father, making the data internally valid. Though Freud’s involvement in this case study may have led to researcher bias, which decreases the internal validity.

Little Hans cannot consent to taking part, making the procedure ethically questionable. Furthermore, the public discussion on a young boy’s sexuality has been deemed inappropriate by many.

Approaches: McGuffin et al.’s Twin Study

Aim: To investigate concordance rates for depression in monozygotic and dizygotic twins.

Procedure: McGuffin et al. studied 177 twins where at least one of the pair suffered from depression. The twins were assessed via a series of tests and interviews by blind researchers, meaning they were unaware as to whether the twins were monozygotic or dizygotic and whether they had depression or not.

Findings: McGuffin et al. found that if one monozygotic twin had depression, there was a 46% chance that the other twin had depression too, meaning monozygotic twins had a concordance rate of 46% whereas dizygotic twins had a concordance rate of 20%.

Conclusion: McGuffin et al. concluded that genetic variation partially contributes to depression.

Longitudinal experiments provide rich and detailed information with insights into behavioural changes over time. Attrition is, however, an issue with longitudinal studies as participants could drop out over time, and it’s likely to be those who have developed the worst that withdraw from studies, lowering the ecological validity.

Monozygotic twins are more likely to be treated similarly, meaning they potentially share more environment than dizygotic twins. This is a confounding variable, and it means that the bigger concordance rate in monozygotic twins might be partly caused by a more similar environment, lowering the internal validity.

Attachment: Schaffer & Emerson’s Stages of Attachment Study

Aim: To investigate the formation of attachments and at what age they occur.

Procedure: Schaffer and Emerson conducted a longitudinal study, using a naturalistic observation of 60 working-class infants from Glasgow in their homes every month for the first year of their lives. They then visited again when the infants were 18 months old. They measured whether the infants showed separation and stranger anxiety, and they conducted interviews with the mothers, asking them questions about the behaviour of their infant.

Findings: The results of this study support the stages of attachment. By 40 weeks, 80% of infants had formed specific attachments, and almost 30% had developed multiple attachments. Schaffer and Emerson also found that infants who formed the strongest attachments often had a caregiver with highly sensitive responsiveness.

Conclusion: As all infants go through the stages of attachment at similar points in time, it can be concluded that there’s a biological influence on the formation of attachments.

Longitudinal experiments provide rich and detailed information with insights into behavioural changes over time. Attrition is, however, an issue with longitudinal studies as participants could drop out over time, and it’s likely to be those who have developed the worst that withdraw from studies, lowering the ecological validity.

Natural observations have high ecological validity and mundane realism as they’re carried out in a realistic environment. However, they disallow researchers to control extraneous variables and therefore limit researchers’ ability to establish a clear cause and effect relationship, decreasing the internal validity.

The findings in this study may be prone to social desirability bias due to the use of interviews, as the infants’ mothers will want to show themselves in a good light, decreasing the study’s internal validity.

This study is considered ethnocentric, meaning it cannot be generalised due to the procedure being biased to individualistic cultures, and only working-class Scottish mothers and infants were used.

Attachment: Ainsworth’s Strange Situation Study

Aim: To identify infant attachment styles.

Procedure: Ainsworth used a controlled observation to study caregiver-infant interaction. She recorded observations every 15 seconds using behavioural categories in 8 scripted episodes.

Findings: Ainsworth found that 60-75% of infants were classified as secure, 20-25% classified as insecure-avoidant and 3% classified as insecure-resistant.

Conclusion: Ainsworth concluded that infants could have one of three types of attachment.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods increase replicability as well as reliability.

Main and Soloman identified a fourth type of attachment (disorganised), implying Ainsworth’s findings are overly simplistic.

This study is considered ethnocentric, meaning it cannot be generalised due to the procedure being biased to individualistic cultures, and only middle-class American mothers and infants were used.

Attachment: Ijzendoorn & Kroonenberg’s Cultural Variation Study

Aim: To investigate whether attachment styles are universal.

Procedure: Ijzendoorn and Kroonenberg conducted a meta-analysis of Ainsworth’s Strange Situation, studying 32 studies across 8 different countries.

Findings: Ijzendoorn and Kroonenberg found that secure attachments are the most common in all countries. In individualistic cultures, insecure-avoidant attachments are the second most common, whereas insecure-resistant attachments are the second most common in collectivist cultures. Furthermore, they found a larger intra-cultural (within a culture) difference as opposed to an inter-cultural (different cultures) difference.

Conclusion: Ijzendoorn and Kroonenberg concluded that secure attachments are the ‘norm’, implying they’re innate.

Lab experiments (Ainsworth’s methodology) allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Standardised methods (Ainsworth’s methodology) increase replicability as well as reliability.

Meta-analyses are reliable and high in internal validity. However, there could be many confounding variables, as the study may not have the same aims as the new one, lowering internal validity.

This study is considered ethnocentric, meaning it cannot be generalised due to the Strange Situation procedure being biased to individualistic cultures, and only middle-class American mothers and infants were used.

Attachment: Bowlby’s 44 Thieves Study

Aim: To investigate the link between early maternal deprivation and later delinquency.

Procedure: Bowlby’s sample consisted of 44 criminal teenagers and 44 non-criminal teenagers - each was interviewed, and Bowlby looked for signs of affectionless psychopathy and prolonged early separation.

Findings: Bowlby categorised 14 of the 44 criminals as affectionless psychopaths, and he found that 12 had experienced prolonged periods of separation within the first 2 years of their lives.

Conclusion: Bowlby concluded there’s a link between early prolonged separation and affectionless psychopathy, suggesting that maternal deprivation as a child leads to delayed development.

Self-report methods like interviews provide rich and detailed information. However, interviewer bias may have impacted findings as Bowlby was the only interviewer used in this study, decreasing the internal validity.

Bowlby’s sample size is very small, so this study lacks population validity, meaning findings are less generalisable.

Attachment: Rutter et al.’s Romanian Orphan Study

Aim: To investigate the effects of early institutionalisation and deprivation on later development in life.

Procedure: Rutter et al. conducted a natural longitudinal study, comparing 165 Romanian orphans who were adopted into British families and 52 British orphans at the ages of 4, 6, 11 and 15.

Findings: Rutter et al. found that the Romanian orphans, if adopted before the age of 6 months, displayed good emotional and cognitive development, but after 6 months they experienced severe psychological damage (e.g. autistic-like behaviour).

Conclusion: Rutter et al. concluded that the effects of institutionalisation can be reversed, given that children adopted before the age of 6 months are provided with a safe and loving environment.

Longitudinal experiments provide rich and detailed information with insights into behavioural changes over time. Attrition is, however, an issue with longitudinal studies as participants could drop out over time, and it’s likely to be those who have developed the worst that withdraw from studies, lowering the ecological validity.

Some children who experience institutionalisation receive ‘special treatment’ and could therefore develop slightly better than others, lowering the external validity.

Biopsychology: Sperry’s Split Brain Study

Aim: To investigate lateralisation in the brain.

Procedure: Sperry conducted a quasi experiment with 11 epileptic patients who had undergone callosotomies. He presented them with visual and tactile stimuli and asked the patients to complete a series of tasks in response to the stimuli.

Findings: In one condition, Sperry found that patients with a split brain struggled to describe objects presented to the left visual field, but could easily draw or select them.

Conclusion: Sperry concluded that the left hemisphere is dominant in language while the right is dominant in motor tasks, suggesting the brain is lateralised.

Lab experiments allow researchers to control extraneous variables and therefore establish a clear cause and effect relationship, increasing the internal validity. However, lab experiments suffer from low ecological validity and mundane realism.

Patients having epilepsy could potentially be a confounding variable, as it means the brain already functions differently, lowering the internal validity. Furthermore, it decreases the generalisability of epilepsy only impacts less than 1% of the population, and callosotomies are also not a common procedure.

Biopsychology: Siffre’s Cave Study

Aim: To investigate whether the body has an internal biological clock.

Procedure: Siffre stayed in a cave for 2 months deprived of external cues (exogenous zeitgebers) like light.

Findings: Siffre found that his sleep-wake cycle settled around 25 hours, suggesting circadian rhythms are controlled by the SCN but influenced by social cues.

Conclusion: Siffre concluded that there is an internal biological clock, but without external cues, the cycle may slightly shift.

The practical applications for this study are diverse. For example, chronotherpeutics (the study of how the timing of medical treatments affects their effectiveness, like chemotherapy).

Siffre used artificial light, which could potentially be a confounding variable, lowering the internal validity.

This study is idiographic because Siffre only studied his own internal biological clock, and he repeated this study at 60 and found that his internal biological clock was slower, suggesting there are factors which prevent general conclusions from being drawn.

Biopsychology: DeCoursey’s SCN Study

Aim: To investigate the role of the SCN and its role in survival.

Procedure: DeCoursey damaged 30 chipmunks’ SCNs and returned them to the wild, and compared them to two control groups, one with ‘sham lesions‘ and another with intact SCNs.

Findings: DeCoursey observed that after 80 days, significantly more of the chipmunks with damaged SCNs died.

Conclusion: DeCoursey concluded that destroying the SCN led to the loss of the sleep-wake cycle and the importance of the SCN in survival.

The chipmunks in the study cannot consent to taking part, making the procedure ethically questionable. They also aren’t protected from harm as they were unnaturally tampered with, which could’ve caused unnecessary distress, and this resulted in some of their deaths.

Humans are much more complex than animals, so the results found in this study cannot be generalised to humans.