First, it is important to know what a notification ceremony is, as political parties no longer hold such events. The closest thing that might come to a notification event in modern times is the press conference where a nominee will announce their selection of the vice presidential nominee.What is a committee of notification? According to An Introduction to Political Parties and Practical Politics written by noted Berkeley Professor of Political Science Perley Orman Ray in 1912.
With the naming of a candidate for vice president, it only remains for the convention to authorize the appointment of a committee consisting of one from each State, formally to notify the presidential candidate of his nomination and a similar committee to notify the vice-presidential candidate. The business of the convention then being at an end, it adjourns sine die. These committees on notification subsequently visits the nominee at his home, or meet him at some appointed place. The chairman, or some other previously selected member, makes a formal speech notifying the candidate the action of the convention. Thereupon the candidate delivers his "speech of acceptance" (p.164-165)
Modern conventions have no notification committees that travel out to nominees homes to hear of their acceptance. Now this all takes place at the highly choreographed political conventions we are accustomed to experiencing today. The 1940s were still the infancy of television. Most families did not see televisions enter their homes until after WWII in the 1950s. The political campaigns of the 1940, '44, and '48 were the last to be done before the majority of Americans owned televisions. Conventions were still affairs for the newspaper and radio services.
Modern day conventions wrap the whole process in a bow for the media. Instead of nominees being selected and ending the convention to travel to them to hear if they accept, the nominees now accept nomination before the actual convention. Nearly all nominees for vice president are known well in advance of the convention. The final night of the convention culminates with the presidential nominee and vice presidential nominee awash in a sea of delegates, balloons and bands. This was not the case in 1940, when Charles McNary accepted his nomination.