Critical Period | Psychology for UPSC Optional (Notes) PDF Download

Introduction

The acquisition of language is a remarkable feat that most individuals seem to effortlessly achieve from an early age. However, an intriguing question arises: what happens if one is deprived of communication from birth? Can language still be acquired? This article delves into the concept known as the Critical Period Hypothesis, which suggests that the development of language to a fluent level is largely dependent on exposure during the early years of life. By exploring the definition, hypothesis, and providing compelling examples, a deeper understanding of the critical period emerges.

Critical Period Hypothesis

The Critical Period Hypothesis (CPH) posits that there is a crucial time frame during which individuals can learn a new language to a native-like proficiency. This critical period typically commences around the age of two and concludes before puberty¹. According to this hypothesis, acquiring a new language beyond this critical window becomes increasingly challenging and less successful.

Critical Period in Psychology

Within the realm of psychology, the critical period holds significant relevance. Psychology frequently intersects with English Language and Linguistics, with language acquisition being a key area of study. Many students have found the free StudySmarter app, with over 22 million users, to be a valuable resource for improving their grades².

Critical Period Psychology Definition

In developmental psychology, the critical period refers to a stage in an individual's maturation when their nervous system is particularly receptive to environmental experiences. If a person does not receive the appropriate environmental stimuli during this period, their ability to acquire new skills is compromised, thereby affecting various social functions in adulthood. When a child passes through the critical period without acquiring a language, the chances of attaining native fluency in their first language become highly improbable³.

Graph of the Ease of Language Acquisition

During the critical period, individuals possess heightened neuroplasticity in their brains, making them primed to acquire new skills. The brain's synapses, which are the connections responsible for transmitting information, are exceptionally receptive to novel experiences, enabling the formation of new neural pathways. However, as individuals progress into adulthood, the brain's plasticity gradually diminishes, making language acquisition more challenging.

Critical and Sensitive Periods

Researchers also refer to the "sensitive period" or "weak critical period," which shares similarities with the critical period. Like the critical period, the sensitive period is characterized by a high level of neuroplasticity, allowing for the rapid formation of new synapses. The key distinction lies in the duration, as the sensitive period is considered to extend beyond puberty, although its boundaries are not strictly defined.

First Language Acquisition in the Critical Period

The Critical Period Hypothesis concerning language acquisition was initially introduced by Eric Lenneberg in his book "Biological Foundations of Language" in 1967. Lenneberg proposed that achieving high-level proficiency in a language can only occur within this critical period. Acquiring a language outside of this period poses greater challenges, diminishing the likelihood of achieving native-like proficiency. Lenneberg based his hypothesis on evidence derived from various cases that impacted children's first language abilities:

• Deaf children who did not develop native proficiency in verbal language after puberty.
• Children who experienced brain injuries had better prospects for recovery compared to adults.
• Children with aphasia had a higher probability of language acquisition compared to adults with aphasia.
• Children who were victims of child abuse during early childhood faced difficulties in language acquisition due to lack of exposure during the critical period.

Critical Period Example: Genie

An exemplar of the critical period is the case of Genie, known as the "feral child," which provides crucial insights into the relationship between the critical period and language acquisition. Genie experienced severe domestic abuse and social isolation from the age of 20 months until 13 years old. During this critical period, she had minimal interaction with others and was unable to develop adequate language skills.
When authorities discovered Genie, she exhibited an inability to speak. Through direct teaching over a few months, she acquired some language skills, albeit at a slow pace. Although her vocabulary expanded over time, she encountered challenges in learning basic grammar and maintaining conversations. Scientists who worked with Genie concluded that her inability to learn a language during the critical period severely hindered her capacity to attain full language competency for the rest of her life. Despite evident improvements in her speech ability, abnormalities persisted, and she struggled with social interaction.
Genie's case offers support for Lenneberg's theory to a certain extent. Nevertheless, academia and researchers continue to debate this topic. Some argue that Genie's development was impeded due to the inhumane and traumatic treatment she endured as a child, which may have contributed to her language learning difficulties.

Second Language Acquisition in the Critical Period

The Critical Period Hypothesis can also be applied to the acquisition of a second language. It pertains to adults or children who are fluent in their first language and endeavor to learn a second language. Proponents of the CPH cite older learners' struggles in fully grasping a second language compared to children and adolescents as evidence. Generally, younger learners achieve greater proficiency in the language, while older individuals often retain foreign accents due to the neuromuscular system's role in speech production.

Adults are less likely to attain a native accent since they have surpassed the critical period for acquiring new neuromuscular functions. However, there are exceptional cases of adults who achieve near-native proficiency in all aspects of a second language, making it challenging to draw definitive conclusions regarding correlation and causation. Critics of the critical period argue that factors such as effort, learning environment, and time dedicated to learning have a more significant impact on an individual's success in acquiring a second language.

Key Takeaways

To summarize, the critical period is typically identified as occurring from early childhood, around the age of two, until puberty. During this period, the brain exhibits heightened neuroplasticity, facilitating the formation of new synaptic connections. Eric Lenneberg's introduction of the Critical Period Hypothesis in 1967, supported by cases such as Genie's, provides evidence of the critical period's influence on language acquisition. However, ongoing debates persist among researchers and academics regarding the applicability and limitations of the critical period in language acquisition.