Dr. Henderson conducted an experiment to investigate the word length effect on short-term memory capacity.

He recruited nine participants using opportunity sampling from a university library. Dr. Henderson created two lists, each containing ten words.

• Condition X (Short Words): Monosyllabic words (e.g., box, cat, pen, sun).
• Condition Y (Long Words): Polysyllabic words (e.g., university, parliament, vocabulary, refrigerator).

Each participant was presented with both lists, one at a time, on a screen for 20 seconds. Immediately after each list was presented, participants were given 1 minute to recall as many words as possible in the correct order.

The results of Dr. Henderson's study are shown in Table 1.

Table 1: Number of words recalled correctly in Condition X and Condition Y