Science for Everybody

Contents

• Introduction
• What is Custodial Sentencing?
• The Four Aims of Custodial Sentencing
• A Tension Between the Aims
• Psychological Effects of Custodial Sentencing
• Research Evidence: Clemmer (1940)
• Research Evidence: Bukstel and Kilmann (1980)
• Research Evidence: Haney, Banks and Zimbardo (1973)
• The Problem of Recidivism
• Evaluation
• Strengths
• Weaknesses
• Summary
• Quick Questions
• Key Terms

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Introduction

Custodial sentencing means sending an offender to prison or another secure institution. It can protect the public and punish offending, but psychologists also examine whether imprisonment changes behaviour, damages wellbeing or reduces future offending.

For AQA A-level Psychology, the specification requires students to understand both the aims of custodial sentencing and its psychological effects.

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What is Custodial Sentencing?

A custodial sentence removes an offender from the community and places them in a secure setting. Sentences vary considerably in length and conditions. Therefore, prison is not one single psychological experience.

Factors such as age, sentence length, previous imprisonment, prison conditions, relationships with other prisoners, family contact and access to treatment can all influence how someone responds to custody.

The AQA specification specifically identifies the aims and psychological effects of custodial sentencing as part of dealing with offending behaviour.

The Four Aims of Custodial Sentencing

1. Deterrence

Deterrence aims to prevent future crime through the threat or experience of punishment.

There are two types.

Individual deterrence occurs when being imprisoned makes the offender less willing to commit another offence.

General deterrence occurs when other members of society avoid offending because they see what may happen if they are caught.

For example, someone considering a serious financial crime may decide that the risk of imprisonment outweighs the possible financial reward.

However, deterrence assumes that offenders consider the consequences of their behaviour. This may not happen when offences are impulsive, emotionally driven or committed under the influence of drugs or alcohol.

Therefore, making a sentence more severe does not necessarily make it a more effective deterrent.

2. Incapacitation

Incapacitation protects society by physically restricting an offender.

While an offender is securely imprisoned, they have far fewer opportunities to commit offences against members of the general public.

This aim is particularly important for offenders judged to pose a serious risk to others.

However, incapacitation mainly works while the person is imprisoned. It does not necessarily change the psychological or social causes of their offending.

If these factors remain unchanged after release, the person may return to offending.

In addition, offences can still occur within prisons. Therefore, incapacitation reduces opportunities for crime rather than eliminating crime entirely.

3. Retribution

Retribution is based on the principle that wrongdoing deserves punishment.

A custodial sentence may therefore act as society’s response to the seriousness of an offence. The punishment should normally be proportionate to the offence committed.

Retribution is sometimes described as the offender paying a debt to society.

This aim differs from rehabilitation because it does not necessarily seek to change the offender. A sentence could therefore achieve retribution even if the person later reoffends.

However, psychologists may question whether punishment alone addresses the cognitive, emotional, behavioural or social factors that contributed to offending.

4. Rehabilitation

Rehabilitation aims to reduce future offending by changing factors that contribute to criminal behaviour.

Within custody, rehabilitation may involve:

• psychological therapy
• anger management
• substance misuse treatment
• education
• literacy and numeracy support
• vocational qualifications
• employment skills
• support preparing for release.

For example, someone whose offending is linked to poor emotional regulation may complete an anger-management programme. Another prisoner may gain qualifications that improve their chances of finding employment after release.

The aim is therefore not simply to punish the offender but to make future offending less likely.

However, rehabilitation depends on the quality of programmes, the motivation of the offender and the support available after release.

A Tension Between the Aims

The four aims do not always fit comfortably together.

For example, an extremely harsh prison environment might satisfy retribution, because it appears strongly punitive. However, high levels of fear and stress could interfere with rehabilitation.

In contrast, a therapeutic prison that provides education, counselling and comfortable conditions may promote rehabilitation but could be criticised for appearing insufficiently punitive.

Therefore, sentencing policy often involves balancing public protection, punishment and behaviour change.

Reflection question: If imprisonment protects society while someone is in prison but leaves them more likely to offend after release, to what extent has the custodial sentence been successful?

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Psychological Effects of Custodial Sentencing

Stress

Imprisonment can involve:

• loss of liberty
• loss of privacy
• separation from family
• reduced personal control
• fear of violence
• overcrowding
• uncertainty
• restricted movement.

These conditions can produce considerable psychological stress.

For example, a newly imprisoned person may suddenly lose control over when they eat, sleep, communicate with family or move around.

Chronic stress may also affect sleep, concentration and emotional regulation.

This matters because high levels of stress could interfere with rehabilitation. Someone experiencing severe distress may find it difficult to concentrate on education, therapy or behaviour-change programmes.

Depression

Some prisoners experience symptoms of depression, including:

• persistent low mood
• hopelessness
• loneliness
• loss of motivation
• reduced self-esteem.

Separation from family, loss of freedom and uncertainty about the future may contribute.

However, psychologists must be cautious about claiming that imprisonment alone causes depression.

People entering prison are not a random sample of society. Some may already have experienced trauma, substance misuse, poverty, homelessness or existing psychological difficulties.

Therefore, the relationship between imprisonment and depression may involve several interacting factors.

Institutionalisation

Institutionalisation occurs when people adapt so strongly to the routines of an institution that they become dependent upon them.

Prisons control many aspects of everyday life. For example, prisoners may be told:

• when to wake
• when to eat
• when they may leave their cell
• when they can exercise
• when they can receive visitors
• when they can work.

Over a long period, some prisoners may become accustomed to having decisions made for them.

After release, they suddenly need to make independent decisions about money, employment, housing, relationships and daily routines.

Consequently, some long-term prisoners may find life outside prison overwhelming.

Institutionalisation may therefore make successful reintegration more difficult.

Prisonisation

Prisonisation refers to adopting the norms and culture of prison life.

The concept was developed by Donald Clemmer (1940). Clemmer described how prisoners may gradually learn the informal values and expectations of the prison community.

For example, prisoners might learn expectations concerning:

• loyalty to other prisoners
• attitudes towards prison staff
• emotional toughness
• avoiding signs of vulnerability
• distrust of authority.

Prisonisation can be explained partly through social learning. Behaviour that gains respect or reduces danger within prison may receive reinforcement from other prisoners.

The problem is that behaviours which are adaptive inside prison may become maladaptive outside.

For example, extreme distrust, emotional detachment or hostility towards authority could make relationships and employment more difficult after release.

Research Evidence: Clemmer (1940)

Researcher and year: Donald Clemmer, 1940.

Aim: To understand prison culture and the way prisoners become adapted to the social environment of imprisonment.

Procedure or method: Clemmer conducted extensive observations and interviews while studying prison communities. He examined the informal social organisation that existed alongside official prison rules.

Findings: Prisoners differed in how strongly they adopted prison norms and customs. Greater involvement with the prisoner community could result in greater acceptance of its attitudes and expectations.

Conclusion: Imprisonment may result in prisonisation, where people learn and adopt the norms and culture of prison life.

Research Evidence: Bukstel and Kilmann (1980)

Researchers and year: Lee Bukstel and Peter Kilmann, 1980.

Aim: To review research investigating the psychological effects of imprisonment.

Procedure or method: Bukstel and Kilmann reviewed 90 experimental studies that examined psychological effects involving performance, personality and attitudes.

Findings: The effects were highly variable. Some individuals deteriorated psychologically, while others improved or showed little noticeable change. Outcomes appeared to depend on factors such as individual differences, crowding, the stage of the sentence and relationships with other prisoners.

The researchers also found considerable methodological weaknesses within the available studies.

Conclusion: Imprisonment does not affect every prisoner in the same way. Psychological effects result from an interaction between the individual and the prison environment.

Research Evidence: Haney, Banks and Zimbardo (1973)

Researchers and year: Craig Haney, Curtis Banks and Philip Zimbardo, 1973.

Aim: To investigate how assigned prisoner and guard roles within a simulated prison might affect behaviour and psychological wellbeing.

Procedure or method: Psychologically screened male student volunteers were randomly assigned to prisoner or guard roles in a simulated prison at Stanford University.

The experiment was intended to last two weeks. However, it ended after only six days because of increasing psychological distress and problematic behaviour.

Findings: Some prisoners displayed anxiety, emotional distress, passivity and depressive reactions. Meanwhile, some guards became increasingly authoritarian and hostile.

Conclusion: Haney, Banks and Zimbardo argued that prison-like situations and social roles can exert powerful effects on behaviour.

However, the Stanford study provides only limited direct evidence about real imprisonment. The participants were university students rather than convicted offenders, and the setting was artificial.

The Problem of Recidivism

Recidivism means committing further offences after receiving a criminal sanction.

It is an important measure when judging whether custody achieves deterrence and rehabilitation.

If someone leaves prison and quickly commits another offence, the custodial sentence has not successfully produced lasting individual deterrence.

Likewise, repeated offending may indicate that underlying criminogenic factors have not been successfully addressed.

Recent Ministry of Justice statistics illustrate the problem. For the July–September 2024 England and Wales cohort, published in July 2026:

• the proven reoffending rate for adults released from custody was 40.6%
• adults released after custodial sentences of less than 12 months had a proven reoffending rate of 68.2%
• adults released after sentences of 12 months or more had a rate of 22.9%.

These figures make short-term custody particularly important when evaluating the effectiveness of imprisonment.

However, they must be interpreted carefully.

The Ministry of Justice specifically warns against simply comparing the effectiveness of different sentences using raw reoffending percentages because offenders receiving different sentences differ in characteristics such as criminal history and risk.

Therefore, the statistics show that recidivism is a substantial practical problem, but they do not prove that imprisonment itself causes reoffending.

Why Might Custody Fail to Reduce Recidivism?

Short Sentences

A short sentence may be long enough to disrupt someone’s life but too short for meaningful rehabilitation.

For example, imprisonment may result in:

• loss of employment
• loss of housing
• breakdown of relationships
• interruption to treatment.

At the same time, there may not be enough time to complete education or psychological programmes.

Prisonisation

Prisoners may develop relationships with more experienced offenders and learn antisocial attitudes.

Therefore, prison could unintentionally expose some individuals to criminal role models.

Institutionalisation

Long-term prisoners may find independent life difficult after release.

Problems managing housing, money, employment and relationships could increase vulnerability to further offending.

Limited Rehabilitation

Overcrowding, staffing problems or limited programme availability may reduce access to treatment.

Therefore, rehabilitation may exist as an aim without always being successfully delivered.

Problems Following Release

Even successful rehabilitation inside prison may be undermined by circumstances outside.

Former prisoners may experience:

• unemployment
• homelessness
• social stigma
• financial problems
• substance misuse
• damaged relationships.

Therefore, reducing recidivism requires both effective prison interventions and strong resettlement support.

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Evaluation

Strengths

Immediate Public Protection

One strength of custodial sentencing is that incapacitation provides immediate public protection. While dangerous offenders remain securely detained, their opportunity to commit offences against members of the general public becomes substantially reduced. Therefore, custody has a clear practical function when an offender presents a serious immediate risk. However, this advantage mainly applies during confinement. Unless offending behaviour changes, risk may return after release. Consequently, incapacitation provides a strong justification for short-term public protection but does not demonstrate long-term rehabilitation.

Opportunities for Rehabilitation

Another strength is that custody can provide structured opportunities for rehabilitation. Education, vocational training, psychological therapies and substance misuse programmes can all target criminogenic needs. For example, prisoners may develop qualifications or emotional-regulation strategies which improve their chances of successful reintegration. Therefore, custody does not have to function purely as punishment. However, the success of rehabilitation depends heavily on programme quality, prisoner engagement and continuity of support after release.

Research Support for Environmental Effects

Research also supports the idea that institutional environments can influence behaviour. Clemmer’s work identified the process of prisonisation, while Haney, Banks and Zimbardo found rapid behavioural and emotional changes within a simulated prison environment. This supports the view that prison should be understood as a powerful social environment rather than simply a physical location. However, the Stanford prison research had major problems with artificiality, ethics and sample bias. Therefore, it should provide illustrative support rather than definitive evidence about real prisoners.

Ecological Validity of Recidivism Data

Finally, recidivism statistics have strong ecological validity because they examine outcomes involving real offenders. Ministry of Justice figures draw on large national populations and therefore provide socially important evidence about what happens after release. However, official statistics only measure offences that become proven. Hidden or undetected offending will not appear within the measure.

Weaknesses

High Recidivism

A major weakness is the high rate of recidivism among some custodial groups. Recent Ministry of Justice figures showed a proven reoffending rate of 68.2% among adults released following custodial sentences of less than 12 months. This challenges the idea that short imprisonment reliably produces rehabilitation or individual deterrence. However, there is a selection problem. People receiving short custodial sentences may differ from other offender groups in criminal history, personal circumstances and risk. Therefore, the figures demonstrate a practical problem but cannot prove that imprisonment caused later offending.

Psychological Distress

Custody may also cause or worsen psychological distress. Loss of liberty, social isolation, fear and reduced personal control may contribute to stress and depression. These effects create an ethical concern because the state has a responsibility for the wellbeing of people it imprisons. Furthermore, serious psychological distress could interfere with rehabilitation. However, Bukstel and Kilmann found that psychological responses varied considerably between individuals. Some deteriorated, others improved and some showed little change. Therefore, it would be too deterministic to state that prison inevitably causes psychological damage.

Institutionalisation and Prisonisation

Another problem concerns institutionalisation and prisonisation. Behaviour which helps someone cope in prison may become counterproductive outside. Emotional toughness, dependence on routines or distrust of authority could make employment and relationships more difficult. Prisoners may also form relationships with experienced offenders. Consequently, an institution intended to reduce crime could potentially expose people to criminogenic influences. However, prison environments differ considerably, so these effects will not occur equally in every institution or prisoner.

Methodological Problems

There are also major methodological problems with research on imprisonment. Researchers cannot ethically or legally randomly assign real offenders to prison simply to investigate its psychological effects. Most evidence therefore comes from correlational studies, official statistics, interviews or natural experiments. Consequently, researchers cannot easily separate the effects of imprisonment from pre-existing differences between prisoners and non-prisoners. This limits causal conclusions.

Sample Bias

Sample bias further reduces generalisability. Much classic prison research concentrated on male prisoners in Western countries. The Stanford prison study used psychologically screened male university students. Therefore, its findings may not apply to women, older prisoners, young offenders or individuals with complex psychological needs.

Cultural Bias

There may also be cultural bias. Prison environments, sentencing practices and rehabilitation programmes differ substantially between countries. Findings from one criminal justice system cannot automatically be applied elsewhere.

Temporal Validity

Finally, some classic research has limited temporal validity. Clemmer’s work dates from 1940. Prison conditions, mental health provision, sentencing policies and rehabilitation practices have changed greatly since then. Nevertheless, modern research continues to use the concept of prisonisation, suggesting that the basic process remains relevant even if its precise form changes.

Quick Questions

What are the four aims of custodial sentencing?

Deterrence, incapacitation, retribution and rehabilitation.

What is the difference between institutionalisation and prisonisation?

Institutionalisation involves becoming dependent on institutional routines, whereas prisonisation involves adopting prison norms, values and culture.

Give two psychological effects associated with imprisonment.

Any two from stress, anxiety, depression, institutionalisation or prisonisation.

What does recidivism mean?

Reoffending after an offender has already received a criminal sanction or intervention.

Why should raw reoffending rates for different sentence types be compared cautiously?

Different offenders receive different sentences and may differ in criminal history, offence type, risk and social circumstances. Therefore, raw differences may reflect selection bias rather than the effect of the sentence itself.

Key Terms

Custodial sentencing – A punishment in which an offender is detained in prison or another secure institution.

Deterrence – Using punishment to discourage offending in the future.

Individual deterrence – Discouraging the person who is punished from offending again.

General deterrence – Discouraging other people from offending because they see the consequences.

Incapacitation – Protecting the public by restricting an offender’s freedom and opportunity to commit further offences.

Retribution – Punishing an offender because society believes wrongdoing deserves a proportionate penalty.

Rehabilitation – Changing an offender’s behaviour, thinking or circumstances so that future offending becomes less likely.

Recidivism – Reoffending after a person has already received a criminal sanction or intervention.

Institutionalisation – Becoming so adapted to the routines and controls of an institution that independent life outside becomes difficult.

Prisonisation – Adopting the norms, values, behaviours and informal culture of prison life.

Psychological distress – Negative emotional states such as severe stress, anxiety or depression.

Criminogenic – A factor or environment that may increase the likelihood of offending.