Meaning: 'Explain' means to make something clear or easy to understand, particularly in the context of providing reasons or justifications.

Wrong options:

• content: 'Content' is a noun that refers to the subject matter, which does not fit grammatically as it cannot follow 'may help.'
• genuine: 'Genuine' is an adjective that describes authenticity, which does not fit the context of providing an explanation.
• visual: 'Visual' is an adjective that describes something related to sight, which does not fit as it does not convey the action of clarifying or making something understandable.
• communicated: 'Communicated' is a past participle that does not fit the structure required after 'may help,' as it does not convey the action of explaining.
• since: 'Since' is a conjunction that indicates time or reason, which does not fit grammatically or contextually in this sentence.
• made-up: 'Made-up' is an adjective that describes something fabricated, which does not fit as it does not convey the action of explaining.
• each: 'Each' is a determiner that refers to individual items, which does not fit as it does not convey the action of explaining.

Correct answer: visual

Explanation: The adjective 'visual' fits grammatically as it describes the type of tests being conducted. Contextually, it aligns with the use of pictures on a computer screen, indicating that the tests are related to sight.

Meaning: 'Visual' refers to something that is related to seeing or sight.

Wrong options:

• content: 'Content' is a noun that refers to the subject matter, which does not fit as it does not describe the type of tests.
• genuine: 'Genuine' is an adjective that describes authenticity, which does not relate to the nature of the tests being conducted.
• explain: 'Explain' is a verb that does not fit grammatically as it does not describe the type of tests.
• communicated: 'Communicated' is a past participle that does not fit as it does not describe the nature of the tests.
• since: 'Since' is a conjunction that indicates time or reason, which does not fit in this context.
• made-up: 'Made-up' is an adjective that describes something fabricated, which does not fit as it does not describe the type of tests.
• each: 'Each' is a determiner that refers to individual items, which does not fit as it does not describe the type of tests.

Correct answer: made-up

Explanation: The term 'made-up' fits grammatically as it describes the type of words used in the tests. Contextually, it indicates that the words were not real but created for the purpose of the study.

Meaning: 'Made-up' refers to something that is fabricated or invented, particularly in the context of words that do not exist in the language.

Wrong options:

• content: 'Content' is a noun that refers to the subject matter, which does not fit as it does not describe the type of words.
• genuine: 'Genuine' is an adjective that describes authenticity, which does not fit as it does not describe the nature of the words used.
• visual: 'Visual' is an adjective that relates to sight, which does not fit as it does not describe the type of words.
• explain: 'Explain' is a verb that does not fit grammatically as it does not describe the type of words.
• since: 'Since' is a conjunction that indicates time or reason, which does not fit in this context.
• communicated: 'Communicated' is a past participle that does not fit as it does not describe the type of words.
• each: 'Each' is a determiner that refers to individual items, which does not fit as it does not describe the type of words.

Correct answer: communicated

Explanation: The verb 'communicated' fits grammatically as it is in the past participle form, which is appropriate after 'were.' Contextually, it indicates how the made-up words were presented to the infants.

Meaning: 'Communicated' means to convey or share information, particularly in the context of how the words were delivered to the infants.

Wrong options:

• content: 'Content' is a noun that refers to the subject matter, which does not fit grammatically as it cannot follow 'were.'
• genuine: 'Genuine' is an adjective that describes authenticity, which does not fit as it does not convey the action of conveying information.
• visual: 'Visual' is an adjective that relates to sight, which does not fit as it does not convey the action of communicating.
• explain: 'Explain' is a verb that does not fit grammatically as it does not describe the action of conveying information.
• since: 'Since' is a conjunction that indicates time or reason, which does not fit in this context.
• made-up: 'Made-up' is an adjective that describes something fabricated, which does not fit as it does not convey the action of communicating.
• each: 'Each' is a determiner that refers to individual items, which does not fit as it does not convey the action of communicating.

Correct answer: each

Explanation: The determiner 'each' fits grammatically as it refers to individual items in a group. Contextually, it indicates that the infants were tested on their recognition of every single word presented to them.

Meaning: 'Each' refers to every one of two or more items considered individually.

Wrong options:

• content: 'Content' is a noun that refers to the subject matter, which does not fit as it does not refer to individual words.
• genuine: 'Genuine' is an adjective that describes authenticity, which does not fit as it does not refer to individual words.
• visual: 'Visual' is an adjective that relates to sight, which does not fit as it does not refer to individual words.
• explain: 'Explain' is a verb that does not fit grammatically as it does not refer to individual words.
• since: 'Since' is a conjunction that indicates time or reason, which does not fit in this context.
• made-up: 'Made-up' is an adjective that describes something fabricated, which does not fit as it does not refer to individual words.
• communicated: 'Communicated' is a past participle that does not fit as it does not refer to individual words.