In which decade were bar code scanners first developed and introduced for practical commercial use in stores?

Introduction / Context:
Bar codes and bar code scanners are now a routine part of shopping and inventory management, but they are relatively recent inventions in the history of technology. Early theoretical ideas existed earlier, yet bar code scanners only became practical when electronics and computing advanced enough to handle them. This question asks you to identify the decade in which bar code scanners were first developed and introduced for real commercial use, especially in supermarkets and retail stores.

Given Data / Assumptions:

• The focus is on bar code scanners, not just the printed bar code idea.
• The question refers to practical commercial use in stores, not just laboratory experiments.
• The options are four decades: 1940s, 1950s, 1960s and 1970s.
• Only one of these decades corresponds to the real world adoption of bar code scanners at checkout counters.

Concept / Approach:
Although the concept of encoding data visually in bars and spaces was explored earlier, reliable commercial bar code scanners became a reality when laser technology and digital electronics were sufficiently developed. The first official scanning of a Universal Product Code on a retail product took place in 1974 at a supermarket in the United States. This event, and the wider rollout of scanners in supermarkets, firmly places the practical introduction of bar code scanning technology in the 1970s. Earlier decades lacked the necessary components and computing power for mass commercial deployment.

Step-by-Step Solution:
Step 1: Realise that bar code scanners needed lasers, photo detectors and digital processing, which were not mature in the 1940s and 1950s.Step 2: Remember that the well known first scanning of a bar coded product occurred in the mid 1970s.Step 3: Compare the given decades and identify the 1970s as matching this timeline.Step 4: Note that the 1960s saw early theoretical and experimental work, but widespread commercial use came slightly later.Step 5: Therefore, select the 1970s as the correct decade for introduction of bar code scanners in stores.

Verification / Alternative check:
Timelines of retail technology often highlight the 1970s as the era of computerised cash registers and the introduction of the Universal Product Code system. The famous story of the first scanned product, a packet of chewing gum, is dated to 1974. No similar stories of regular supermarket scanning appear in credible sources for the 1940s, 1950s or 1960s. This alignment of historical accounts confirms that the 1970s are correct.

Why Other Options Are Wrong:
The 1940s and 1950s were too early for the widespread development of lasers and integrated circuits necessary for bar code scanning systems. The 1960s saw some early patent work and experimental designs, but commercial supermarkets did not yet adopt bar code scanners at scale. Therefore, these decades do not meet the condition of practical commercial use in stores and are incorrect choices.

Common Pitfalls:
Some candidates assume that because bar codes appear simple, they must be very old and may guess 1940s or 1950s. Others may confuse the date of the first bar code concept with the date of the first scanner used at a checkout. The question explicitly mentions scanners and commercial use, so it is crucial to focus on when supermarkets actually implemented the technology. Keeping that detail in mind will guide you to the 1970s as the right answer.

Final Answer:
Bar code scanners were first developed and introduced for practical commercial use in the 1970s.