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This experiment was conducted to study, if participants took a longer time to name the incongruent ink colours as compared to the congruent ink colours. In this experiment, there are 22 first year Engineering students from Republic Polytechnic who were tasked to name the ink colours of the congruent and incongruent ink colours as fast as they could. In addition, the dependent variable is the time taken whereas the independent variable is the 25 congruent colour words and the 25 incongruent colour words. Results from the experiment showed that due to automatic and controlled process, interference occurs, causing an increase in the reaction time for the participants to name the ink colour of the 25 incongruent colour words as compared to naming the ink colour of the 25 congruent colour words.
The serial position curve for forward serial recall is the sine qua non of modeling in short-term memory; all theories accommodate the extensive primacy (i.e., superior performance for early list items) and limited recency (i.e., advantage for terminal items). This pattern reverses with backward recall, in which case steep and extensive recency but little primacy is observed (e.g., Li & Lewandowsky, 1993). Symmetry of primacy and recency is achieved with a reconstruction task (e.g, Lewandowsky, Nimmo, & Brown, in press; Nairne, 1992). Perhaps somewhat surprisingly, few models (if any) accommodate backward recall and reconstruction, and we therefore restrict consideration to the serial position curve for forward recall.
One of the most robust findings about memory for lists is that it is often characterized by enhanced memory for the first and last list items, termed primacy and recency, respectively (Atkinson and Shiffrin, 1968). The combination of primacy and recency produces a U-shaped serial position curve for accuracy. In humans, the U-shaped serial position curve is observed when lists consist of either words (Rundus, 1971), abstract visual patterns (Korsnes et al., 1996), or spatial locations (Smyth and Scholey, 1996). It is also observed in tests of both free recall (Carlesimo et al., 1996)
and recognition (Wright et al., 1990). While not as extensively documented in nonhumans as it is in humans, the U-shaped serial position curve has been observed in Old World monkeys (Sands and Wright, 1980), New World monkeys (Wright, 1999), rats (Kesner and Novak, 1982), pigeons (Santiago and Wright, 1984),
(Crystal and Shettleworth, 1994), suggesting that it reflects fundamental memory processes common across species. In humans, studies of memory for lists have often identified rehearsal as the underlying mechanism responsible for the primacy effect (Atkinson and Shiffrin, 1968). Because earlier list items enter our working memory first, they are rehearsed more than later items, facilitating the transfer of those earlier items into long-term memory and enhancing later accessibility to retrieval.
Several types of evidence point to a critical role for rehearsal in primacy. When asked to rehearse aloud, subjects spontaneously rehearse the first list item more than the later list items (Rundus, 1971; Tan and Ward, 2000). Having subjects complete a distraction task during list presentation reduces primacy and instructions that rehearsal is unnecessary (i.e., that no memory test will follow) eliminate primacy while leaving recency intact (Glenberg et al., 1980; Marshall and Werder, 1972). Directed forgetting instructions, in which subjects are cued that rehearsal of specific list items is unnecessary, affect memory for early list items (primacy), but not later list items (Sahakyan and Foster, 2009).
Amnesic patients, who have damage to the hippocampus and for whom rehearsal is ineffective at transferring information to long-term memory, have poor memory for early list items (primacy), but normal memory for later list items (recency), relative to control subjects (Baddeley and Warrington, 1970; Carlesimo et al., 1996). Taken together, this evidence strongly suggests that the primacycomponentof the characteristic
U-shaped serial position curve observed in humans is due to rehearsal. In contrast to studies with humans, studies with nonhumans often focus on memory interference as the underlying cause of primacy. According to the interference account, memory for initial list items interferes with later list items and memory for later list items interferes with earlier list items (Wright, 1998). Memory is worst for items in the middle of the list because those items receive both proactive and retroactive interference. These types of interference are proposed to follow different time courses, depending on the length of time elapsing from stimulus exposure (hereafter: study) to when the subject is required to make a test response (hereafter: test). Retroactive interference is strongest at short study-test delays and proactive interference is strongest at longer study-test delays.
This account has been used to explain the shift from only recency at short delays, to a U-shaped serial position curve at moderate delays, and finally to only primacy at long delays (Wright et al., 1985). This shift from primacy, to primacy and recency, to recency has been termed the dynamic serial position curve and has been observed in pigeons, monkeys and people (Wright et al., 1985; but see Kerr et al., 1998, 1999 for reports that did not find a dynamic serial position curve in humans). If the characteristic U shape of the serial position curve is due, at least in part, to rehearsal, then we might expect it to occur only with familiar items or items that can be recorded in terms of existing representations in long-term memory. Consistent with this, most studies of memory for lists in humans use stimuli that are at least somewhat familiar to the subjects. Humans are often tested with word stimuli, and even when stimuli are not words, humans may recode them verbally (e.g., a photograph of a blue boat might be recorded as the words "blue boat"). When to be remembered items are coded or recoded verbally, memory for them may become dependent on activation of existing representations (i.e. words) in long-term memory, rather than on the generation of completely new memory traces. For example, when asked to study lists of nouns (Baddeley and Warrington, 1970) or travel
slides (Wright et al., 1990), subjects presumably have existing representations of the nouns or the objects pictured in the travel slides. Studies inhumanssuggest that activation of such existing representations in long-term memory is critical for primacy. Photographs of familiar household items produce primacy in humans, whereas
photographs of unfamiliar shapes do not (Swanson, 1978). Direct manipulation of familiarity by pre-exposing subjects to abstract shapes affects primacy but not recency (Dugas, 1975). This suggests that memory for lists of familiar stimuli will be more likely to result in the typical U-shaped serial position curve than memory for lists of unfamiliar stimuli. One way to increase the familiarity of to-be-remembered items in nonhumans, and presumably ensure they are represented in long-term memory, is to use a small set of repeating stimuli to generate lists for memory tests.
We examined how rhesus monkeys' memory for lists, as depicted by a serial position curve, changes based on the size of the image set from which the lists are drawn. Six monkeys performed a serial probe recognition (SPR) test with 5-item lists of photographs drawn from either large, medium, or small image sets. In SPR tests,
subjects see a list of stimuli, experience a delay, and then see a single stimulus that they must judge as either from the studied list or not. Over many trials, the subject's memory is repeatedly probed using stimuli from all possible list positions, as well as distractor stimuli that were not from the studied list. The result is a serial position curve that depicts memory accuracy as a function of list position. Some studies have found that the shape of the serial position curve changes as a function of the delay between study and test, with a shift from recency only, to a U-shape with primacy and recency, and then finally to only primacy as the delay between the last study item and test increases (Wright et al., 1985). To maximize the chances of capturing such dynamic effects, if they occurred in our study, we tested memory for items from lists drawn from each set size at delays varying from 0.2 to 50 s. Based on results from humans showing the importance of stimulus familiarity to the primacy portion of the serial position curve (Dugas, 1975; Swanson, 1978), we hypothesized that the extent to which we obtained primacy would vary as a function of the size of the set from which images were
drawn, with the smaller sets generating the most primacy.
Smith (2009) said that the standard interpretation of the serial position curve is that it reflects two components of memory: short term memory and long term memory. In addition, Smith (2009) theory is that 5 minutes of running backwards adversely affects memory, but only short term memory.
The current study was conducted to test if 5 minutes of running backwards adversely affects memory, but only short term memory. It is therefore hypothesized running backwards for 5 minutes will affect the serial position curve, but only one component of this curve.
The participants were 100 university student volunteers who were readers of English. The experiment was conducted in a quiet room and the participants were being tested one at a time. The order of the participants taking the experiment was based on drawing lots and all participants have at least seven hours of sleep the day before taking the experiment.
In this experiment, there is a sequence of letter strings and the participant is tasked to classify each item either as a word or a non-word by pressing the "j" or "f" key respectively on the keyboard. After the completion of each correct classification task, the participant would be prompt to recall the consonant trigram by typing in the letters in the correct order that appeared before the classification task. The dependent variable is the percentage of the total number of correct words being recalled whereas the independent variable is the distractor duration of 1 second, 11 seconds and 21 seconds.
The participants were seated in front of the computer 10 minutes prior to taking the experiment. After which, the participants were tasked to click on the button, "Brown- Peterson" to begin the experiment. A window will appear that fills nearly the entire screen, and a smaller window will appear with abbreviated instructions. The participants would then be tasked to read the instructions and click on the space bar to start a trial. In the middle of the screen, a trigram of letters will appear for two seconds. Following which, the participants would be given a sequence of letter strings and must classify each item either as a word by pressing the "j" key, or a non-word by pressing the "f" key. The duration of time spent classifying the letter strings will vary from one to twenty-one seconds. After correct completion of the classification task, the participants would be prompted to recall the consonant trigram. Using the keyboard, the participants were to type in the letters, in the correct order that appeared before the classification task. When the participants are ready for the next trial, they are prompt to press the space bar again.
For the trial to count, the participants must correctly classified almost all the letter strings as words or non-words. If the participants make any mistakes, the trial will be repeated later in the experiment. The rate of the sequence will change from trial to trial. It will become slower if the participants make a mistake and be faster if the participants get it correct. There are a total of 18 trials that must be run to finish the experiment. At the end of the experiment, the experiment window will close and a new window will appear that displays the participant's data as a table and a plot and provides an explanation of the experiment and results.
The output data was obtained using SPSS version 16.0. The participants were tasked to read aloud the 25 congruent words and the 25 incongruent words. The time taken to complete the congruent and incongruent words for both groups of participants was recorded and compared. The mean reaction time taken to complete the congruent words was (M = 22.89, SD = 3.24). The mean reaction time to complete the incongruent words was (M = 28.32, SD = 4.17). There was a mean difference of (M = 5.44, SD = 3.96) between the time taken to complete congruent words and incongruent words. This result, however, was statistically significant, as t (10) = -4.56, p < .05.