Abstract

The main objective of the research was to try and ascertain whether the global superiority effect is affected by the symbols, images or objects involved. The research had three hypotheses that were tested based on the results. The experiments used the E-prime software to gather data from participants who are students from The Open University. This data was later analyzed using the SPSS software. From the results, the average response from local stimuli was faster than that of global stimuli. Letter targets also received a quicker response compared to shape targets. There was also a significant interaction between target level and target type. The conclusion was that global superiority effect is affected by other variables involved.

 

 1.Introduction

For some time, the notion that global visual scenes are quickly recognized compared to the local features has been suggested and tested in different areas. Pashler (2002) asserts that when people are presented with an object, first they conceptualize what the object is before trying to identify the finer details associated with this object. A good example is a picture; first an individual will have to identify what the object presented to them is. This is then followed by extraction of more evidence as they continue to look at it. What this means is that the picture itself is identified more quickly than the finer details that it encompasses. Such aspects have made Johnson (2010) to conclude that perceptual processes are usually organized temporarily such that they proceed from a global structuring towards a finer analysis.  The effect might be dependent on the size, spatial frequency or hierarchical level. This is because the neural explanation behind this is not clearly understood. Several experiments have been conducted with the objective of trying to ascertain these assertions.

 

1.1 Literature Review

Navon, D. (1977). Study of Global vs. Local Perceptual Processing. C81 MPA – Practical Methods, 21.

With this research, Navon wanted to find out whether participants can control their perceptual process when they are told what to ignore and what to focus on. For the design of the experiment, participants were presented with two characters; H and S. They were required to indicate whether H or S was the global character and the same applied for the local character. Stimuli were presented for 40ms. Latency and accuracy that were measured with every stimulus were recorded after every trial. One session comprised of 288 trials whereby the participants were allowed to rest for 20 sec after every 36 trials. Each stimulus appeared randomly six times in a block. The global directed condition was first given to half of the participants while the other half received it last. The experiment involved fourteen participants who were undergraduate students at the University of California. From the results, measures of variability have not been given in the experiment, but the overall error stood at 3.3%. The differences were not significant at 0.05 level. The only significant difference was between the conflicting consistency conditions when the attention was directed towards the elements, p˂0.01. Mean latency in ‘conflicting’ trails in the local directed condition was higher compared to ‘consistent’ trails. Navon concluded that the global pattern receives faster response compared to the local pattern. People have the ability of responding to global patterns without facing any interference from local features. However, they do not have the ability of processing local features without awareness of the ‘whole’ (Navon, 1977).

 

Norman, S. (2012). Global Superiority does not apply in all Circumstances. 13.

This research was aimed at identifying whether the precedence that global factors have over local factors tend to defer when different symbols are used. For the design of the experiment, the research used both letters and shapes in attempt of trying to make a conclusion. The experiment used two-way repeated measures ANOVA, whereby there were two sets of independent variables. The first set comprised of the local and global factors, while the second set comprised of letters and shapes.  Capital ‘N’ was used to identify the global letter and its lower case;’n’ local letters. Global shapes were represented by big circles while local shapes were represented by small circles. They were represented as 60 stimuli, and the participants were required to identify whether it was a global shape or letter, or whether they belonged to local after being displayed. Each image was displayed for 150ms, and the RT was used as the dependent variable. The experiment used 19 students, all of whom were students. After every student providing their data, their means were run through SPSS for repeated measures ANOVA. From the results, response to local stimuli seemed to be 4ms slower than that of global stimuli on average. For the second set of independent variables, letters were responded to 17ms faster compared to shapes. The significant main effect was on the second set of independent variable where letters were responded to quickly than shapes. Norman (2012) concluded that global superiority is dependent on the nature of symbols being used.

 

1.2 Aims

This study in its own scope aims at ascertaining whether the global superiority effect tends to be affected by the type of symbols or images involved. That is whether letters and shapes are processed differently. The information derived from this experiment will help to ascertain the claims or conclusions made in previous studies regarding this topic.

The research will have two sets of independent variables; one comprising target level and the other target type. Target level is comprised of global and local stimuli, while the target type is comprised of letters and shapes. Data from 145 students will be used as it will be prepared through the E-prime software and then analyzed using SPSS software.

 

1.3 Hypotheses

1. There is a significant difference between the Target Level of independent variables; global and local.
2. There will be a main effect on the Target Type.
3. There is a significant interaction involving the independent variables of Target type and Target Level.
4. Method

 

2.1 Design

The experiment used a 2×2 repeated measures design. This means that there were two independent variables with two levels each, and all the participants performed all the four conditions required for the experiment. The first independent variable was the ‘Target Level’, which entailed two levels; local and global. This can be recognized as the global to local account of visual perception. The second independent variable was ‘Target Type’, which encompassed two levels; shapes and letters. The 2×2 repeated measures design with the four conditions were represented as follows: 1) Global Target + Letter Target (N); 2) Local Target + Letter Target (n); 3) Global Target + Shape Target (large triangle); 4) Local Target + Shape Target (small triangle).The shapes and letters were presented at both local and global levels as 100 stimuli developed using Adobe Illustrator. The four stimuli were removed and the remaining 96 were presented in a random manner. The participants were required to press a button whenever a triangle shape or letter ‘N’ was presented at the local or global level. Every image was presented for 120 ms bearing an inter-stimulus interval of two seconds. The time that participants took to identify a shape or letter was measured. The reaction time of each participant was viewed as the dependent variable for this experiment.

 

2.2 Participants

Students from The Open University were used as the participants. 145 participants were involved, and whose information was derived from the final Navondata. The students used their identification numbers for recognition purposes.

 

2.3 Materials

The materials used for this experiment included E-prime and SPSS software. Stimuli presentation was conducted using E-prime. The stimuli used included Navon letters and shapes, which were developed in Adobe Illustrator.

 

2.4 Procedure

Each participant was required to download the Navon experiment on the E-prime software. The experiment contained 96 stimuli, and the participants were required to click on the images that appeared on the screen of either the letter or shape. Each stimulus was displayed for 120ms entailing an inter-stimulus interval of 2 seconds. After completion of the experiment, participants were required to upload the results to the university website, using their identification numbers as the labels. The data from all the participants was combined, and was made available for download from the website. For this research, the downloaded data was from 145 participants. Using the downloaded data, there was calculation of the mean response of the reaction time for every participant. This data was exported to the SPSS software where 2×2 repeated-measures ANOVA was conducted.

 

 

3.Results

 

 

Table 1

	Target.type-letter	Target.type-shape	Sub-row means for Target.level
Target.level – Global	519 (11.3)	574 (14.2)	546
Target.level – Local	541 (12.8)	541 (11.3)	541
Sub-column means for Target.type	530	557	543(Grand mean)

 

From the table above, it is apparent that on average the response time to local stimuli were 5ms faster compared to Global stimuli response. On the other hand, responses for letter targets were 27ms faster compared to shape targets.

There did not seem to be a main effect of target level (F˂1). However, there was a significant main effect of target type (F (1, 133) =8.90, p= .003) on response time. The letter targets received a quicker response compared to shape targets.

 

Graph 1

There was a significant interaction between target type and target level (F (1, 133) = 9.98, p=.002) on the response time. The difference between RTs for shapes and letters was larger at the global level compared to the difference at the local level, which showed no difference. Global letters were recognized more quickly than local letters. However, global shapes were recognized more slowly than the local shapes.

4.Discussion

The first hypothesis stating that there was significant difference between the target levels was rejected. This is because the difference between the two was not large. However, the local targets were responded to more quickly than the global targets. The second hypothesis stating that there was a main effect on the target type was accepted. This is because on average the letter targets received a quicker response than the shape targets. There was a difference of 27ms and this is significant. The third hypothesis that postulated that there was a significant interaction between target type and target level was also accepted.

The relationship between this research and the researches in the literature review is somehow mixed. This is because there is a similarity and a difference at the same time. In his study, Navon concluded that global patterns receive faster response compared to the local patterns. The results in this study tend to differ with this conclusion. This is because from the research, on average the response time to local stimuli was 5ms faster compared to Global stimuli response. The response time for global letters was faster than that of local letters, but that of the shapes went in the opposite direction. When it comes to the second study in the literature review there seems to be a similarity. Norman (2012) concluded that global superiority is dependent on the nature of symbols being used. The results from this experiment have revealed this to be the case. From the results, on average the local targets have appeared to receive a quicker response than the global targets. However, when it came to the identification of letters the global targets were recognized faster than the local targets. The case was different for shapes identification since the difference went in the opposite direction. What this means is that global superiority exists, but not on ever thing. It will depend on the symbols, images, objects among others that are being observed at that moment. There are those situations when global superiority will showcase and there are those situations when it will not be manifested.

The main aim of this research was to ascertain whether global superiority is affected by the nature of objects or images involved. The results have shown that there is a difference. This means that different objects, images and symbols tend to be processed differently in the human brain. For this reason, how one is recognized might be different from the other one.

The limitation of this research is based on the sample data used for the experiment. The data was derived from The Open University Students, but there was no criteria used in choosing the participants. Individuals tend to be different in various ways. An individual might be fast or slow in identifying things based on how they are themselves. Sometimes the environment around people can be a determining factor on how they tend to process information while recognizing things. Maybe if the study collected data from individuals subjected to a different environment, the results would have been different. This qualifies as a limitation since we cannot tell confidently whether if a sample of participants were from an environment that is completely different from this, the results would be the same.

Among the ways that this study can be improved is altering the methods section a little bit on the part concerning participants. Data should not be derived from participants subjected in the same environment. Participants of the study should come from completely different environments in order to increase the reliability of the findings. This is because an environment usually affects how people perceive things and hence deriving data from individuals based in the same environment would hinder the realization of the actual state.

The implication of the findings is that they will trigger further research in this field. This is more so because of how the results turned out different from Navon’s study. From the results, on average the local targets seemed to have a quicker response compared to global targets. This might raise curiosity for other interested researchers as it is against what they would expect to find. The curiosity aspect will trigger further researches in order for individuals to make informed conclusions.

In the future for people involved in researching this topic, I would want to see them add another variable for men and women. The objective here would be to ascertain whether global superiority manifests itself in the same way for both genders. It might be that it affects one of them more than the other and that’s why it prevails in various researches that have been concluded before. Such a move would add to new knowledge on this topic.

In conclusion, this study was aimed at ascertaining whether the global superiority effect tends to be affected by the type of symbols or images involved. It involved data from 145 participants who are students from The Open University. The conclusion from the results obtained is that global superiority effect is really affected by the symbols or images involved. People tend to process different things differently. This finding has shown a similarity with previous research that was conducted by Norman (2012).

 

References

Johnson, S. (2010). Neoconstructivism the new science of cognitive development. New York: Oxford University Press.

Navon, D. (1977). Study of Global vs. Local Perceptual Processing. C81 MPA – Practical Methods, 21.

Norman, S. (2012). Global Superiority Does not apply in all Circumstances. 13.

Pashler, H. (2002). Stevens’ Handbook of experimental psychology (3rd ed.). New York: Wiley.

 

 

 
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