認知の柔軟性

定義の具体性に関わらず、研究者たちは一般的に、認知の柔軟性は実行機能、つまり自分の思考を制御する能力を含む高次の認知の一要素であるという点で合意している。^{[ 14 ]}実行機能には、抑制、記憶、情緒安定性、計画、組織化など、認知の他の側面も含まれる。認知の柔軟性は、抑制、計画、ワーキングメモリなど、これらの能力の多くと密接に関連している。^{[ 9 ]}したがって、個人が刺激の側面を抑制してより重要な側面に集中できる場合（つまり、物体の色を抑制して物体の種類に集中する場合）、認知の柔軟性も高くなる。この意味で、計画、組織化、特定の記憶戦略の活用が得意になる。^{[ 15 ]}

研究者たちは、認知の柔軟性も心理学者ジャン・ピアジェが最初に提唱した多重分類の構成要素であると主張している。多重分類課題では、参加者（主にこのスキルを既に習得しているか、習得中の子供）は、対象物を一度に複数の異なる方法で分類しなければならず、それによって対象物について柔軟に考えることになる。^{[ 16 ]}同様に、認知的に柔軟であるためには、幼い子供が対象物や状況の1つの側面にのみ焦点を当てる傾向である中心化を克服しなければならない。^{[ 17 ]}例えば、子供が幼いときは、対象物の1つの側面（つまり対象物の色）にのみ焦点を当てることができ、両方の側面（つまり対象物の色と種類）に焦点を当てることができない場合がある。したがって、研究によると、個人の思考が中心化されている場合、認知的に柔軟性が低くなる傾向がある。

Research has suggested that cognitive flexibility is related to other cognitive abilities, such as fluid intelligence, reading fluency, and reading comprehension.^[16][18] Fluid intelligence, described as the ability to solve problems in new situations, enables fluid reasoning ability. When one is able to reason fluidly, they are in turn more likely to be cognitively flexible. Furthermore, those who are able to be cognitively flexible have been shown to have the ability to switch between and/or simultaneously think about sounds and meanings, which increases their reading fluency and comprehension. Cognitive flexibility has also been shown to be related to one's ability to cope in particular situations. For example, when individuals are better able to shift their thinking from situation to situation they will focus less on stressors within these situations.^[19]

In general, researchers in the field focus on development of cognitive flexibility between the ages of three and five.^[20] However, cognitive flexibility has been shown to be a broad concept that can be studied with all different ages and situations.^[3] Thus, with tasks ranging from simple to more complex, research suggests that there is a developmental continuum that spans from infancy to adulthood.

In the A-not-B task, children are shown an object hidden at Location A within their reach, and are then prompted to search for the object at Location A, where they find it. This activity is repeated several times, with the hidden object at Location A. Then, in the critical trial and while the child is watching, the object is hidden in Location B, a second location within easy reach of child. Researchers have agreed that the A-not-B task is a simple task that effectively measures cognitive flexibility during infancy.^[20][21]

次元変化カード分類課題（DCCS）では、子どもたちは最初にカードを単一の次元（色など）で分類するように求められ、その後、戦略を変更してカードを2番目の次元（形など）に基づいて分類するように求められます。^{[ 22 ]}通常、3歳児はカードを単一の次元に基づいて分類できますが、2番目の次元に基づいてカードを分類するように切り替えることはできません。しかし、5歳児はカードを1つの次元に基づいて分類することができ、その後、カードを2番目の次元で分類するように切り替えることができます。^{[ 21 ] [ 23 ]}

多段階分類カード分類課題では、子どもたちはカードを見せられ、2つの異なる次元（例えば、黄色と青などの色、動物と食べ物などの物体の種類）に基づいて、マトリックス内の4つの山（例えば、黄色の動物、黄色の食べ物、青色の動物、青色の食べ物）に同時に分類するように求められます。この課題は、7歳の子どもが2つの次元に基づいてカードを同時に分類することができなかったという研究結果から、より難しいものと思われます。これらの子どもたちは2つの次元に別々に焦点を当てていましたが、11歳になると、子どもたちはこれら2つの次元に基づいてカードを同時に分類できるようになりました。これは、7歳から11歳の間で認知の柔軟性が高まっていることを示しています。^{[ 12 ] [ 16 ]}

ウィスコンシンカード分類テスト（WCST）は、個人の抽象的推論能力と、必要に応じて問題解決戦略を変更する能力を判断するために使用されます。^{[ 24 ]}

このテストでは、参加者に複数のカードが提示されます。カードに描かれた図は、色、数量、形が異なります。参加者はカードを一致させるように指示されますが、どのように一致させるかは指示されません。ただし、特定の一致が正しいか間違っているかは伝えられます。一致ルールを切り替える能力が測定されます。通常、9歳から11歳の子どもは、このテストに必要な認知的な柔軟性を示します。^{[ 3 ] [ 21 ]}

ストループテストは、カラーワードネーミングテストとも呼ばれます。このテストでは、デッキに3種類のカードがあります。「カラーカード」にはさまざまな色のパッチが表示され、参加者はできるだけ早くそれらを識別するように求められます。「ワードカード」には、黒と白のインクで印刷された色の名前が表示され、参加者は再びできるだけ早くそれらの名前を答えるように求められます。最後のカードタイプは「カラーワードカード」で、色の名前が矛盾する色のインクで印刷されています（たとえば、REDという単語が黄色で印刷されます）。参加者は、矛盾する色の名前を無視して、インクの色を答える必要があります。各カードの基本スコアは、参加者が口頭で応答するのにかかる合計時間（秒）です。^{[ 25 ]}通常、インクの色が色の名前と一致しない場合、単語の色を答えるのに時間がかかり、エラーも多くなります。このような状況では、大人は子供よりも反応に時間がかかる傾向がある。なぜなら、大人は単語の実際の色に敏感であり、印刷された矛盾する色の単語を答える際に、その色に影響されやすいからである。

Children can be strikingly inflexible when assessed using traditional tests of cognitive flexibility, but this does not come as a surprise considering the many cognitive processes involved in the mental flexibility, and the various developmental trajectories of such abilities. With age, children generally show increases in cognitive flexibility which is likely a product of the protracted development of the frontoparietal network evident in adults, with maturing synaptic connections, increased myelination and regional gray matter volume occurring from birth to mid-twenties.^[32]

Diminished cognitive flexibility has been noted in a variety of neuropsychiatric disorders such as anorexia nervosa, obsessive–compulsive disorder, schizophrenia, autism, and in a subset of people with ADHD.^[33][34] Each of these disorders exhibit varying aspects of cognitive inflexibility. For example, those with obsessive–compulsive disorder experience difficulty shifting their attentional focus as well as inhibiting motor responses.^[35] Children with autism show a slightly different profile with deficits in adjusting to changing task contingencies, while often maintaining the ability to respond in the face of competing responses.^[36] Potential treatments may lie in neurochemical modulation. Juveniles with anorexia nervosa have marked decreases in set-shifting abilities, possibly associated with incomplete maturation of prefrontal cortices associated with malnutrition.^[37] One can also consider people with addictions to be limited in cognitive flexibility, in that they are unable to flexibly respond to stimuli previously associated with the drug.^[38]

The elderly often experience deficits in cognitive flexibility. The aging brain undergoes physical and functional changes including a decline in processing speed, central sensory functioning, white matter integrity, and brain volume. Regions associated with cognitive flexibility such as the PFC and PC atrophy, or shrink, with age, but also show greater task-related activation in older individuals when compared to younger individuals.^[39] This increase in blood flow is potentially related to the evidence that atrophy heightens blood flow and metabolism, which is measured as the BOLD response, or blood-oxygen-level dependence, with fMRI. Studies suggest that aerobic exercise and training can have plasticity inducing effects that could potentially serve as an intervention in old age that combat the decline in executive function.^[40]

Cognitive flexibility and other executive function skills are crucial to success both in classroom settings and life. A study examining the impact of cognitive intervention for at-risk children in preschool classrooms found that children who received such intervention for one to two years significantly outperformed their peers. Compared to same-age children who were randomly assigned to the control condition (a literacy unit developed by the school district), preschoolers who received intervention achieved accuracy scores of 85% on tests of inhibitory control (self-discipline), cognitive flexibility, and working memory.^[41] Their peers in the control (no intervention) condition, on the other hand, demonstrated only 65% accuracy. Educators involved in this study ultimately opted to implement the cognitive skills training techniques instead of the district-developed curriculum.

Further indicative of the role cognitive flexibility plays in education is the argument that how students are taught greatly impacts the nature and formation of their cognitive structures, which in turn affect students' ability to store and readily access information.^[4] A crucial aim of education is to help students learn as well as appropriately apply and adapt what they have learned to novel situations. This is reflected in the integration of cognitive flexibility into educational policy regarding academic guidelines and expectations. For example, as outlined in the Common Core State Standards Initiative, a standards-based education reform developed to increase high school graduation rates, educators are expected to present within the classroom "high level cognitive demands by asking students to demonstrate deep conceptual understanding through the application of content knowledge and skills to new situations."^[42] This guideline is the essence of cognitive flexibility, and a teaching style focused on promoting it has been seen to foster understanding especially in disciplines where information is complex and nonlinear.^[43] A counterexample is evident in cases where such material is presented in an oversimplified manner and learners fail to transfer their knowledge to a new domain.