The first reason put forth by psychologists was that no single individual feels the absolute pressure to intervene when the responsibility for intervention is shared among multiple observers, and thus, no one takes the initiative to offer help to the distressed person. However, when there is only one onlooker, he/she is more likely to help the person in distress because of his/her individualistic pressure to intervene. However, the individual bystander may also choose to ignore and not offer help, if his/her personal security is threatened or if he/she does not wish to get unnecessarily involved in the situation. The second consideration submitted by the duo was that, even though a bystander cannot closely observe the other bystanders, on seeing multiple bystanders, he may assume that the emergency is being resolved by the others, and his own efforts to intervene would be useless, or perhaps cause further confusion or damage. This way, the passive bystander justifies his inaction by assuring himself that others are there to intervene and help the individual in distress.

Experiment 1 This was one of the first ever experiments conducted to determine whether the presence of other people near the distressed person inhibited the bystanders from intervening to offer assistance. A bunch of college students (subjects) were made to sit in a cubicle and instructed to speak to fellow students using an intercom. The students were also instructed that only one student would be allowed to use the intercom at one time and that they would be speaking either individually, in a pair, or in a group of six. What the student subjects were not told was that there would be only one confederate (assistant to the research) who would be speaking with them. During the conversation with the fellow students, the confederate was instructed to mention that he had suffered episodes of seizure in the past. The confederate then pretended that he was having a seizure attack during the conversation and screamed for help from the fellow students. The experiment revealed the following results:

• 85% of students in the pair setting left their room to look for help because they thought they were the only witness to the crisis.
• 62% of students from the three-person group, offered to help the student suffering from a seizure.
• Only 31% of students from the six-person group left the room to help the person in distress.

These results were attributed to an evident 'diffusion of responsibility', wherein the presence of multiple bystanders reduced their sense of personal responsibility to help the distressed person. Experiment 2 Realistic experiments were conducted by the duo, in order to prove the hypothesis that with the presence of more bystanders in an emergency, the possibility of any one bystander taking the initiative to offer help will not only be less likely but also slow. In one of the experiments conducted to test this hypothesis, the student subjects were assessed under the pretext of filling out a questionnaire. There were three experimental scenarios that were created to test the results.

1. The first one involved making subjects sit alone in one of the rooms and fill the questionnaire.
2. The second scenario involved making three subjects sit together in a room.
3. The third scenario involved making one of the subjects sit with two research confederates, who were instructed to pretend that they were students as well.

The premise of the experiment was to record how the subjects would react in the face of an emergency. While the subjects were going through their questionnaire, smoke was filled into the room to make it appear as if there is a possible fire threat. The experiment revealed the following results:

• 75% of subjects who were sitting alone, reported the smoke to the experimenter.
• Only 38% of subjects sitting in a group of three reported the smoke.
• Only 10% of subjects who sat with the confederates, reported the fire, because the confederates were instructed to ignore the smoke when it appeared and act 'not bothered.'

The explanation of only 10% of subjects reporting the smoke in the last experiment, verified that bystanders often get misled by the reactions of others around them. In this case, since the two confederates did not show any traces of fear or panic, most of the subjects controlled their behavior and chose to not react either. This tendency to not react is known as 'pluralistic ignorance', wherein the supposed calm reaction of other people is construed as a sign that everything is fine and there is no emergency. These experiments led to the hypothesis that the presence of more people can significantly delay the reaction time of bystanders. Experiment 3 Another experiment was carried out by psychologists John Darley and Daniel Batson at the Princeton campus, to check the relation between lateness and the bystander effect. A confederate student was asked to feign illness and was seen by the other students. Although the campus students saw the slumped and visibly distressed student groaning, only 10% stopped to show their concern and offer help, even though they were late. However, when not running against time, more than 60% students offered their help to the student in distress.

Ambiguity: Being unclear as to whether a person requires help or not, can severely affect the reaction of bystanders. Bystanders are also less likely to help if they are unsure about their own well-being and would rarely put themselves at risk. Group Cohesiveness: Bystanders who are familiar with one another are more likely to work as a team and be the first to offer assistance to the person in distress. Studies conducted in this area revealed that the less cohesive groups were the slowest and disinclined to offer their help, as compared to the high cohesive groups who were familiar with one another. Similarities: Research based on altruism found that a bystander was more inclined to help the person in distress, if there was something in common between them, such as the same gender, being football fans, and the victim wearing a football jersey. Familiar Environment: A bystander who is familiar with the locality and knows his way in and around the place, will be more inclined to help the victim because he will feel more secure in doing so. Diffusion of Responsibility: The presence of multiple bystanders immediately reduced the personal responsibility of the passive bystander. The fact that others can help and the belief that someone else is more qualified to intervene and assist, makes most bystanders withdraw and not participate in helping the victim.

I, for one, have witnessed this psychological phenomenon and experienced its desensitizing effect on the bystanders present during the episode. Which is why I wished to gain a deeper understanding of this phenomenon. While waiting to cross the road on a peculiarly hot afternoon, a lady standing besides me, crossed the road a bit too early and was instantly slammed by a motorcyclist. At one moment, she was standing and the next, I saw her rolling on the road from the impact. I did not think, I did not calculate my next move, all I remember doing was running towards her. A huge group of people had surrounded her and were just standing there, shocked and unmoving. No one budged to help the injured woman. I had to shove and push my way through the circle to reach her. The motorcyclist was there, and he seemed too shocked for words. When I approached her, I noticed that copious amounts of blood was oozing from her ear and that she was barely conscious. I tried to wake her up and checked her breathing, which was barely noticeable. I knew there was no time to call the ambulance, and something had to be done immediately. Someone was kind enough to call for a taxicab, and I somehow managed to pick her up! I was assisted by a man, who also offered to take her to the hospital. I gave him my phone number and instructed him to call me and keep me updated. The motorcyclist accompanied the accident victim to the hospital. The victim's husband called to inform me that his wife needed to be operated and that the doctors had told him that had she not been brought in so early, she would have probably died. That's when I realized that had I been a bit late or not offered to help, that woman would not have made it, and that still sends shivers down my spine ...