Has the "direct method" of language learning been shown to be superior to translation-based methods?

Question

The textbook I'm using to learn Latin, called Lingua Latina per se Illustrata, is an example of the "direct method" of language instruction. The text is entirely written in Latin, and progresses slowly from very basic vocabulary and syntax to more advanced concepts.

Here's what the first page looks like, opposite an image of a map showing the locations of various locations in Southern Europe:

My question is, have any studies been done that demonstrate that this method of language instruction is superior to methods that use both L1 and L2 as part of the instruction? Has it been found to produce better results in particular types of students?

Answer 1

The direct method was, for its time, a revolutionary way of learn to communicate verbally in the target language. Up until that point, new languages were learned most often through grammar-translation methods.

Direct method is superior for learning to communicate verbally compare to translation methods. However, the Coleman Report (1929) stated that teaching a language through learning to read it was more appropriate for Language schools in the US.

This leads to the conclusion that the best method depends on what the goals of the learners are.

See Robert Owens (2012): Language Development: An Introduction. Pearson.

Answer 2

Direct methods are statistically considered as superior (Source) to translation methods in letting the learner to communicate faster with others as direct methods focus on allowing the learner to be actively involved in listening and speaking the new language:

This method is also known as the oral or natural method. It is based on the active involvement of the learner in both speaking and listening to the new language in realistic everyday situations. The process consists of a gradual acquisition of grammatical structure and vocabulary. The learner is encouraged to think in the target language rather than translate. He or she hears and uses the language before seeing it written. The writing is done with homework that reinforces what has been learned during the lesson...

The Direct Method gives the learner the ability to communicate quickly because he/she is encouraged to be creative during practice. It gives, by far, the widest range of capability to understand what another person says to you and in developing your capability to speak. This is the method of choice for instruction with a live trainer and where speaking and listening are most important.

If the learner values speaking and listening over grammar and language structure, direct methods are best compared to translation methods. Of course, it really depends on what you want to learn (Source, which is a Microsoft file which must be downloaded from the link):

Methods are held to be fixed teaching systems with prescribed techniques and practices, and approaches are language teaching philosophies that can be interpreted and applied in a variety of different ways in the classroom. All these language teaching methods has its advantage, but as well as its disadvantage. The educator should select the method of teaching according to the situation and the suitability to the students.

If the first source is credible and reliable (in which it should), the second source should also prove that direct methods are superior to translation methods only when the learner is focusing on listening (and understanding what they are hearing) and speaking the new language without involvement of their mother tongue.